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QuantumCircuit

qiskit.circuit.QuantumCircuit(*regs, name=None, global_phase=0, metadata=None) GitHub(opens in a new tab)

Bases: object(opens in a new tab)

Create a new circuit.

A circuit is a list of instructions bound to some registers.

Parameters

  • regs (list(Register) or list(int) or list(list(Bit))) –

    The registers to be included in the circuit.

    • If a list of Register objects, represents the QuantumRegister and/or ClassicalRegister objects to include in the circuit.

      For example:

      • QuantumCircuit(QuantumRegister(4))
      • QuantumCircuit(QuantumRegister(4), ClassicalRegister(3))
      • QuantumCircuit(QuantumRegister(4, 'qr0'), QuantumRegister(2, 'qr1'))
    • If a list of int, the amount of qubits and/or classical bits to include in the circuit. It can either be a single int for just the number of quantum bits, or 2 ints for the number of quantum bits and classical bits, respectively.

      For example:

      • QuantumCircuit(4) # A QuantumCircuit with 4 qubits
      • QuantumCircuit(4, 3) # A QuantumCircuit with 4 qubits and 3 classical bits
    • If a list of python lists containing Bit objects, a collection of Bit s to be added to the circuit.

  • name (str(opens in a new tab)) – the name of the quantum circuit. If not set, an automatically generated string will be assigned.

  • global_phase (float(opens in a new tab) orParameterExpression) – The global phase of the circuit in radians.

  • metadata (dict(opens in a new tab)) – Arbitrary key value metadata to associate with the circuit. This gets stored as free-form data in a dict in the metadata attribute. It will not be directly used in the circuit.

Raises

CircuitError – if the circuit name, if given, is not valid.

Examples

Construct a simple Bell state circuit.

from qiskit import QuantumCircuit
 
qc = QuantumCircuit(2, 2)
qc.h(0)
qc.cx(0, 1)
qc.measure([0, 1], [0, 1])
qc.draw('mpl')
../_images/qiskit-circuit-QuantumCircuit-1.png

Construct a 5-qubit GHZ circuit.

from qiskit import QuantumCircuit
 
qc = QuantumCircuit(5)
qc.h(0)
qc.cx(0, range(1, 5))
qc.measure_all()

Construct a 4-qubit Bernstein-Vazirani circuit using registers.

from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit
 
qr = QuantumRegister(3, 'q')
anc = QuantumRegister(1, 'ancilla')
cr = ClassicalRegister(3, 'c')
qc = QuantumCircuit(qr, anc, cr)
 
qc.x(anc[0])
qc.h(anc[0])
qc.h(qr[0:3])
qc.cx(qr[0:3], anc[0])
qc.h(qr[0:3])
qc.barrier(qr)
qc.measure(qr, cr)
 
qc.draw('mpl')
../_images/qiskit-circuit-QuantumCircuit-2.png

Attributes

ancillas

Returns a list of ancilla bits in the order that the registers were added.

calibrations

Return calibration dictionary.

The custom pulse definition of a given gate is of the form {'gate_name': {(qubits, params): schedule}}

clbits

Returns a list of classical bits in the order that the registers were added.

data

Return the circuit data (instructions and context).

Returns

a list-like object containing the CircuitInstructions for each instruction.

Return type

QuantumCircuitData

global_phase

Return the global phase of the current circuit scope in radians.

instances

= 182

layout

Return any associated layout information about the circuit

This attribute contains an optional TranspileLayout object. This is typically set on the output from transpile() or PassManager.run() to retain information about the permutations caused on the input circuit by transpilation.

There are two types of permutations caused by the transpile() function, an initial layout which permutes the qubits based on the selected physical qubits on the Target, and a final layout which is an output permutation caused by SwapGates inserted during routing.

metadata

The user provided metadata associated with the circuit.

The metadata for the circuit is a user provided dict of metadata for the circuit. It will not be used to influence the execution or operation of the circuit, but it is expected to be passed between all transforms of the circuit (ie transpilation) and that providers will associate any circuit metadata with the results it returns from execution of that circuit.

num_ancillas

Return the number of ancilla qubits.

num_clbits

Return number of classical bits.

num_parameters

The number of parameter objects in the circuit.

num_qubits

Return number of qubits.

op_start_times

Return a list of operation start times.

This attribute is enabled once one of scheduling analysis passes runs on the quantum circuit.

Returns

List of integers representing instruction start times. The index corresponds to the index of instruction in QuantumCircuit.data.

Raises

AttributeError(opens in a new tab) – When circuit is not scheduled.

parameters

The parameters defined in the circuit.

This attribute returns the Parameter objects in the circuit sorted alphabetically. Note that parameters instantiated with a ParameterVector are still sorted numerically.

Examples

The snippet below shows that insertion order of parameters does not matter.

>>> from qiskit.circuit import QuantumCircuit, Parameter
>>> a, b, elephant = Parameter("a"), Parameter("b"), Parameter("elephant")
>>> circuit = QuantumCircuit(1)
>>> circuit.rx(b, 0)
>>> circuit.rz(elephant, 0)
>>> circuit.ry(a, 0)
>>> circuit.parameters  # sorted alphabetically!
ParameterView([Parameter(a), Parameter(b), Parameter(elephant)])

Bear in mind that alphabetical sorting might be unintuitive when it comes to numbers. The literal “10” comes before “2” in strict alphabetical sorting.

>>> from qiskit.circuit import QuantumCircuit, Parameter
>>> angles = [Parameter("angle_1"), Parameter("angle_2"), Parameter("angle_10")]
>>> circuit = QuantumCircuit(1)
>>> circuit.u(*angles, 0)
>>> circuit.draw()
   ┌─────────────────────────────┐
q:U(angle_1,angle_2,angle_10)
   └─────────────────────────────┘
>>> circuit.parameters
ParameterView([Parameter(angle_1), Parameter(angle_10), Parameter(angle_2)])

To respect numerical sorting, a ParameterVector can be used.

>>> from qiskit.circuit import QuantumCircuit, Parameter, ParameterVector
>>> x = ParameterVector("x", 12)
>>> circuit = QuantumCircuit(1)
>>> for x_i in x:
...     circuit.rx(x_i, 0)
>>> circuit.parameters
ParameterView([
    ParameterVectorElement(x[0]), ParameterVectorElement(x[1]),
    ParameterVectorElement(x[2]), ParameterVectorElement(x[3]),
    ..., ParameterVectorElement(x[11])
])

Returns

The sorted Parameter objects in the circuit.

prefix

= 'circuit'

qubits

Returns a list of quantum bits in the order that the registers were added.


Methods

add_bits

add_bits(bits) GitHub(opens in a new tab)

Add Bits to the circuit.

add_calibration

add_calibration(gate, qubits, schedule, params=None) GitHub(opens in a new tab)

Register a low-level, custom pulse definition for the given gate.

Parameters

Raises

Exception(opens in a new tab) – if the gate is of type string and params is None.

add_register

add_register(*regs) GitHub(opens in a new tab)

Add registers.

append

append(instruction, qargs=None, cargs=None) GitHub(opens in a new tab)

Append one or more instructions to the end of the circuit, modifying the circuit in place.

The qargs and cargs will be expanded and broadcast according to the rules of the given Instruction, and any non-Bit specifiers (such as integer indices) will be resolved into the relevant instances.

If a CircuitInstruction is given, it will be unwrapped, verified in the context of this circuit, and a new object will be appended to the circuit. In this case, you may not pass qargs or cargs separately.

Parameters

Returns

a handle to the CircuitInstructions that were actually added to the circuit.

Return type

qiskit.circuit.InstructionSet

Raises

CircuitError – if the operation passed is not an instance of Instruction .

assign_parameters

assign_parameters(parameters: Mapping[Parameter, ParameterExpression | float] | Sequence[ParameterExpression | float], inplace: Literal[False] = False, *, flat_input: bool = False, strict: bool = True) → QuantumCircuit GitHub(opens in a new tab)

assign_parameters(parameters: Mapping[Parameter, ParameterExpression | float] | Sequence[ParameterExpression | float], inplace: Literal[True] = False, *, flat_input: bool = False, strict: bool = True) → None

Assign parameters to new parameters or values.

If parameters is passed as a dictionary, the keys should be Parameter instances in the current circuit. The values of the dictionary can either be numeric values or new parameter objects.

If parameters is passed as a list or array, the elements are assigned to the current parameters in the order of parameters which is sorted alphabetically (while respecting the ordering in ParameterVector objects).

The values can be assigned to the current circuit object or to a copy of it.

Note

When parameters is given as a mapping, it is permissible to have keys that are strings of the parameter names; these will be looked up using get_parameter(). You can also have keys that are ParameterVector instances, and in this case, the dictionary value should be a sequence of values of the same length as the vector.

If you use either of these cases, you must leave the setting flat_input=False; changing this to True enables the fast path, where all keys must be Parameter instances.

Parameters

  • parameters – Either a dictionary or iterable specifying the new parameter values.
  • inplace – If False, a copy of the circuit with the bound parameters is returned. If True the circuit instance itself is modified.
  • flat_input – If True and parameters is a mapping type, it is assumed to be exactly a mapping of {parameter: value}. By default (False), the mapping may also contain ParameterVector keys that point to a corresponding sequence of values, and these will be unrolled during the mapping, or string keys, which will be converted to Parameter instances using get_parameter().
  • strict – If False, any parameters given in the mapping that are not used in the circuit will be ignored. If True (the default), an error will be raised indicating a logic error.

Raises

  • CircuitError – If parameters is a dict and contains parameters not present in the circuit.
  • ValueError(opens in a new tab) – If parameters is a list/array and the length mismatches the number of free parameters in the circuit.

Returns

A copy of the circuit with bound parameters if inplace is False, otherwise None.

Examples

Create a parameterized circuit and assign the parameters in-place.

from qiskit.circuit import QuantumCircuit, Parameter
 
circuit = QuantumCircuit(2)
params = [Parameter('A'), Parameter('B'), Parameter('C')]
circuit.ry(params[0], 0)
circuit.crx(params[1], 0, 1)
circuit.draw('mpl')
circuit.assign_parameters({params[0]: params[2]}, inplace=True)
circuit.draw('mpl')
../_images/qiskit-circuit-QuantumCircuit-3_00.png../_images/qiskit-circuit-QuantumCircuit-3_01.png

Bind the values out-of-place by list and get a copy of the original circuit.

from qiskit.circuit import QuantumCircuit, ParameterVector
 
circuit = QuantumCircuit(2)
params = ParameterVector('P', 2)
circuit.ry(params[0], 0)
circuit.crx(params[1], 0, 1)
 
bound_circuit = circuit.assign_parameters([1, 2])
bound_circuit.draw('mpl')
 
circuit.draw('mpl')
../_images/qiskit-circuit-QuantumCircuit-4_00.png../_images/qiskit-circuit-QuantumCircuit-4_01.png

barrier

barrier(*qargs, label=None) GitHub(opens in a new tab)

Apply Barrier. If qargs is empty, applies to all qubits in the circuit.

Parameters

  • qargs (QubitSpecifier) – Specification for one or more qubit arguments.
  • label (str(opens in a new tab)) – The string label of the barrier.

Returns

handle to the added instructions.

Return type

qiskit.circuit.InstructionSet

break_loop

break_loop() GitHub(opens in a new tab)

Apply BreakLoopOp.

Warning

If you are using the context-manager “builder” forms of if_test(), for_loop() or while_loop(), you can only call this method if you are within a loop context, because otherwise the “resource width” of the operation cannot be determined. This would quickly lead to invalid circuits, and so if you are trying to construct a reusable loop body (without the context managers), you must also use the non-context-manager form of if_test() and if_else(). Take care that the BreakLoopOp instruction must span all the resources of its containing loop, not just the immediate scope.

Returns

A handle to the instruction created.

Raises

CircuitError – if this method was called within a builder context, but not contained within a loop.

Return type

InstructionSet

cast

static cast(value, type_) GitHub(opens in a new tab)

Best effort to cast value to type. Otherwise, returns the value.

Return type

S | T

cbit_argument_conversion

cbit_argument_conversion(clbit_representation) GitHub(opens in a new tab)

Converts several classical bit representations (such as indexes, range, etc.) into a list of classical bits.

Parameters

clbit_representation (Object) – representation to expand

Returns

Where each tuple is a classical bit.

Return type

List(tuple(opens in a new tab))

ccx

ccx(control_qubit1, control_qubit2, target_qubit, ctrl_state=None) GitHub(opens in a new tab)

Apply CCXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit1 (QubitSpecifier) – The qubit(s) used as the first control.
  • control_qubit2 (QubitSpecifier) – The qubit(s) used as the second control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

ccz

ccz(control_qubit1, control_qubit2, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CCZGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit1 (QubitSpecifier) – The qubit(s) used as the first control.
  • control_qubit2 (QubitSpecifier) – The qubit(s) used as the second control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘10’). Defaults to controlling on the ‘11’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

ch

ch(control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CHGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

clear

clear() GitHub(opens in a new tab)

Clear all instructions in self.

Clearing the circuits will keep the metadata and calibrations.

cls_instances

classmethod cls_instances() GitHub(opens in a new tab)

Return the current number of instances of this class, useful for auto naming.

Return type

int(opens in a new tab)

cls_prefix

classmethod cls_prefix() GitHub(opens in a new tab)

Return the prefix to use for auto naming.

Return type

str(opens in a new tab)

compose

compose(other, qubits=None, clbits=None, front=False, inplace=False, wrap=False) GitHub(opens in a new tab)

Compose circuit with other circuit or instruction, optionally permuting wires.

other can be narrower or of equal width to self.

Parameters

Returns

the composed circuit (returns None if inplace==True).

Return type

QuantumCircuit

Raises

  • CircuitError – if no correct wire mapping can be made between the two circuits, such as if other is wider than self.
  • CircuitError – if trying to emit a new circuit while self has a partially built control-flow context active, such as the context-manager forms of if_test(), for_loop() and while_loop().
  • CircuitError – if trying to compose to the front of a circuit when a control-flow builder block is active; there is no clear meaning to this action.

Examples

>>> lhs.compose(rhs, qubits=[3, 2], inplace=True)
            ┌───┐                   ┌─────┐                ┌───┐
lqr_1_0: ───┤ H ├───    rqr_0: ──■──┤ Tdg ├    lqr_1_0: ───┤ H ├───────────────
            ├───┤              ┌─┴─┐└─────┘                ├───┤
lqr_1_1: ───┤ X ├───    rqr_1: ┤ X ├───────    lqr_1_1: ───┤ X ├───────────────
         ┌──┴───┴──┐           └───┘                    ┌──┴───┴──┐┌───┐
lqr_1_2:U1(0.1)+                     =  lqr_1_2:U1(0.1) ├┤ X ├───────
         └─────────┘                                    └─────────┘└─┬─┘┌─────┐
lqr_2_0: ─────■─────                           lqr_2_0: ─────■───────■──┤ Tdg ├
            ┌─┴─┐                                          ┌─┴─┐        └─────┘
lqr_2_1: ───┤ X ├───                           lqr_2_1: ───┤ X ├───────────────
            └───┘                                          └───┘
lcr_0: 0 ═══════════                           lcr_0: 0 ═══════════════════════
 
lcr_1: 0 ═══════════                           lcr_1: 0 ═══════════════════════

continue_loop

continue_loop() GitHub(opens in a new tab)

Apply ContinueLoopOp.

Warning

If you are using the context-manager “builder” forms of if_test(), for_loop() or while_loop(), you can only call this method if you are within a loop context, because otherwise the “resource width” of the operation cannot be determined. This would quickly lead to invalid circuits, and so if you are trying to construct a reusable loop body (without the context managers), you must also use the non-context-manager form of if_test() and if_else(). Take care that the ContinueLoopOp instruction must span all the resources of its containing loop, not just the immediate scope.

Returns

A handle to the instruction created.

Raises

CircuitError – if this method was called within a builder context, but not contained within a loop.

Return type

InstructionSet

control

control(num_ctrl_qubits=1, label=None, ctrl_state=None, annotated=False) GitHub(opens in a new tab)

Control this circuit on num_ctrl_qubits qubits.

Parameters

Returns

The controlled version of this circuit.

Return type

QuantumCircuit

Raises

CircuitError – If the circuit contains a non-unitary operation and cannot be controlled.

copy

copy(name=None) GitHub(opens in a new tab)

Copy the circuit.

Parameters

name (str(opens in a new tab)) – name to be given to the copied circuit. If None, then the name stays the same.

Returns

a deepcopy of the current circuit, with the specified name

Return type

QuantumCircuit

copy_empty_like

copy_empty_like(name=None) GitHub(opens in a new tab)

Return a copy of self with the same structure but empty.

That structure includes:

  • name, calibrations and other metadata
  • global phase
  • all the qubits and clbits, including the registers

Parameters

name (str(opens in a new tab)) – Name for the copied circuit. If None, then the name stays the same.

Returns

An empty copy of self.

Return type

QuantumCircuit

count_ops

count_ops() GitHub(opens in a new tab)

Count each operation kind in the circuit.

Returns

a breakdown of how many operations of each kind, sorted by amount.

Return type

OrderedDict

cp

cp(theta, control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CPhaseGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • theta (ParameterValueType) – The angle of the rotation.
  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

crx

crx(theta, control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CRXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • theta (ParameterValueType) – The angle of the rotation.
  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

cry

cry(theta, control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CRYGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • theta (ParameterValueType) – The angle of the rotation.
  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

crz

crz(theta, control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CRZGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • theta (ParameterValueType) – The angle of the rotation.
  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

cs

cs(control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CSGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

csdg

csdg(control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CSdgGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

cswap

cswap(control_qubit, target_qubit1, target_qubit2, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CSwapGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit1 (QubitSpecifier) – The qubit(s) targeted by the gate.
  • target_qubit2 (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. '1'). Defaults to controlling on the '1' state.

Returns

A handle to the instructions created.

Return type

InstructionSet

csx

csx(control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CSXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

cu

cu(theta, phi, lam, gamma, control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CUGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • theta (ParameterValueType) – The θ\theta rotation angle of the gate.
  • phi (ParameterValueType) – The ϕ\phi rotation angle of the gate.
  • lam (ParameterValueType) – The λ\lambda rotation angle of the gate.
  • gamma (ParameterValueType) – The global phase applied of the U gate, if applied.
  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

cx

cx(control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit (QubitSpecifier) – The qubit(s) used as the control.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

cy

cy(control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CYGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit (QubitSpecifier) – The qubit(s) used as the controls.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

cz

cz(control_qubit, target_qubit, label=None, ctrl_state=None) GitHub(opens in a new tab)

Apply CZGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubit (QubitSpecifier) – The qubit(s) used as the controls.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.
  • ctrl_state (str(opens in a new tab) |int(opens in a new tab) | None) – The control state in decimal, or as a bitstring (e.g. ‘1’). Defaults to controlling on the ‘1’ state.

Returns

A handle to the instructions created.

Return type

InstructionSet

dcx

dcx(qubit1, qubit2) GitHub(opens in a new tab)

Apply DCXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

decompose

decompose(gates_to_decompose=None, reps=1) GitHub(opens in a new tab)

Call a decomposition pass on this circuit, to decompose one level (shallow decompose).

Parameters

Returns

a circuit one level decomposed

Return type

QuantumCircuit

delay

delay(duration, qarg=None, unit='dt') GitHub(opens in a new tab)

Apply Delay. If qarg is None, applies to all qubits. When applying to multiple qubits, delays with the same duration will be created.

Parameters

Returns

handle to the added instructions.

Return type

qiskit.circuit.InstructionSet

Raises

CircuitError – if arguments have bad format.

depth

depth(filter_function=<function QuantumCircuit.<lambda>>) GitHub(opens in a new tab)

Return circuit depth (i.e., length of critical path).

Parameters

filter_function (callable) – A function to filter instructions. Should take as input a tuple of (Instruction, list(Qubit), list(Clbit)). Instructions for which the function returns False are ignored in the computation of the circuit depth. By default filters out “directives”, such as barrier or snapshot.

Returns

Depth of circuit.

Return type

int(opens in a new tab)

Notes

The circuit depth and the DAG depth need not be the same.

draw

draw(output=None, scale=None, filename=None, style=None, interactive=False, plot_barriers=True, reverse_bits=None, justify=None, vertical_compression='medium', idle_wires=True, with_layout=True, fold=None, ax=None, initial_state=False, cregbundle=None, wire_order=None, expr_len=30) GitHub(opens in a new tab)

Draw the quantum circuit. Use the output parameter to choose the drawing format:

text: ASCII art TextDrawing that can be printed in the console.

mpl: images with color rendered purely in Python using matplotlib.

latex: high-quality images compiled via latex.

latex_source: raw uncompiled latex output.

Warning

Support for Expr nodes in conditions and SwitchCaseOp.target fields is preliminary and incomplete. The text and mpl drawers will make a best-effort attempt to show data dependencies, but the LaTeX-based drawers will skip these completely.

Parameters

  • output (str(opens in a new tab) | None) – Select the output method to use for drawing the circuit. Valid choices are text, mpl, latex, latex_source. By default the text drawer is used unless the user config file (usually ~/.qiskit/settings.conf) has an alternative backend set as the default. For example, circuit_drawer = latex. If the output kwarg is set, that backend will always be used over the default in the user config file.

  • scale (float(opens in a new tab) | None) – Scale of image to draw (shrink if < 1.0). Only used by the mpl, latex and latex_source outputs. Defaults to 1.0.

  • filename (str(opens in a new tab) | None) – File path to save image to. Defaults to None (result not saved in a file).

  • style (dict(opens in a new tab) |str(opens in a new tab) | None) –

    Style name, file name of style JSON file, or a dictionary specifying the style.

    • The supported style names are "iqp" (default), "iqp-dark", "clifford", "textbook" and "bw".
    • If given a JSON file, e.g. my_style.json or my_style (the .json extension may be omitted), this function attempts to load the style dictionary from that location. Note, that the JSON file must completely specify the visualization specifications. The file is searched for in qiskit/visualization/circuit/styles, the current working directory, and the location specified in ~/.qiskit/settings.conf.
    • If a dictionary, every entry overrides the default configuration. If the "name" key is given, the default configuration is given by that style. For example, {"name": "textbook", "subfontsize": 5} loads the "texbook" style and sets the subfontsize (e.g. the gate angles) to 5.
    • If None the default style "iqp" is used or, if given, the default style specified in ~/.qiskit/settings.conf.
  • interactive (bool(opens in a new tab)) – When set to True, show the circuit in a new window (for mpl this depends on the matplotlib backend being used supporting this). Note when used with either the text or the latex_source output type this has no effect and will be silently ignored. Defaults to False.

  • reverse_bits (bool(opens in a new tab) | None) – When set to True, reverse the bit order inside registers for the output visualization. Defaults to False unless the user config file (usually ~/.qiskit/settings.conf) has an alternative value set. For example, circuit_reverse_bits = True.

  • plot_barriers (bool(opens in a new tab)) – Enable/disable drawing barriers in the output circuit. Defaults to True.

  • justify (str(opens in a new tab) | None) – Options are left, right or none. If anything else is supplied, it defaults to left justified. It refers to where gates should be placed in the output circuit if there is an option. none results in each gate being placed in its own column.

  • vertical_compression (str(opens in a new tab) | None) – high, medium or low. It merges the lines generated by the text output so the drawing will take less vertical room. Default is medium. Only used by the text output, will be silently ignored otherwise.

  • idle_wires (bool(opens in a new tab)) – Include idle wires (wires with no circuit elements) in output visualization. Default is True.

  • with_layout (bool(opens in a new tab)) – Include layout information, with labels on the physical layout. Default is True.

  • fold (int(opens in a new tab) | None) – Sets pagination. It can be disabled using -1. In text, sets the length of the lines. This is useful when the drawing does not fit in the console. If None (default), it will try to guess the console width using shutil.get_terminal_size(). However, if running in jupyter, the default line length is set to 80 characters. In mpl, it is the number of (visual) layers before folding. Default is 25.

  • ax (Any | None) – Only used by the mpl backend. An optional matplotlib.axes.Axes object to be used for the visualization output. If none is specified, a new matplotlib Figure will be created and used. Additionally, if specified there will be no returned Figure since it is redundant.

  • initial_state (bool(opens in a new tab)) – Adds 0|0\rangle in the beginning of the qubit wires and 00 to classical wires. Default is False.

  • cregbundle (bool(opens in a new tab) | None) – If set to True, bundle classical registers. Default is True, except for when output is set to "text".

  • wire_order (list(opens in a new tab)[int(opens in a new tab)] | None) – A list of integers used to reorder the display of the bits. The list must have an entry for every bit with the bits in the range 0 to (num_qubits + num_clbits).

  • expr_len (int(opens in a new tab)) – The number of characters to display if an Expr is used for the condition in a ControlFlowOp. If this number is exceeded, the string will be truncated at that number and ‘…’ added to the end.

Returns

TextDrawing or matplotlib.figure or PIL.Image or str(opens in a new tab):

  • TextDrawing (if output='text')

    A drawing that can be printed as ascii art.

  • matplotlib.figure.Figure (if output='mpl')

    A matplotlib figure object for the circuit diagram.

  • PIL.Image (if output='latex’)

    An in-memory representation of the image of the circuit diagram.

  • str (if output='latex_source')

    The LaTeX source code for visualizing the circuit diagram.

Raises

Example

from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit
qc = QuantumCircuit(1, 1)
qc.h(0)
qc.measure(0, 0)
qc.draw(output='mpl', style={'backgroundcolor': '#EEEEEE'})
../_images/qiskit-circuit-QuantumCircuit-5.png

ecr

ecr(qubit1, qubit2) GitHub(opens in a new tab)

Apply ECRGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

find_bit

find_bit(bit) GitHub(opens in a new tab)

Find locations in the circuit which can be used to reference a given Bit.

Parameters

bit (Bit) – The bit to locate.

Returns

A 2-tuple. The first element (index)

contains the index at which the Bit can be found (in either qubits, clbits, depending on its type). The second element (registers) is a list of (register, index) pairs with an entry for each Register in the circuit which contains the Bit (and the index in the Register at which it can be found).

Return type

namedtuple(int(opens in a new tab), List[Tuple(Register, int(opens in a new tab))])

Notes

The circuit index of an AncillaQubit will be its index in qubits, not ancillas.

Raises

Return type

BitLocations

for_loop

for_loop(indexset: Iterable[int], loop_parameter: Parameter | None, body: None, qubits: None, clbits: None, *, label: str | None) → ForLoopContext GitHub(opens in a new tab)

for_loop(indexset: Iterable[int], loop_parameter: Parameter | None, body: QuantumCircuit, qubits: Sequence[Qubit | QuantumRegister | int | slice | Sequence[Qubit | int]], clbits: Sequence[Clbit | ClassicalRegister | int | slice | Sequence[Clbit | int]], *, label: str | None) → InstructionSet

Create a for loop on this circuit.

There are two forms for calling this function. If called with all its arguments (with the possible exception of label), it will create a ForLoopOp with the given body. If body (and qubits and clbits) are not passed, then this acts as a context manager, which, when entered, provides a loop variable (unless one is given, in which case it will be reused) and will automatically build a ForLoopOp when the scope finishes. In this form, you do not need to keep track of the qubits or clbits you are using, because the scope will handle it for you.

For example:

from qiskit import QuantumCircuit
qc = QuantumCircuit(2, 1)
 
with qc.for_loop(range(5)) as i:
    qc.h(0)
    qc.cx(0, 1)
    qc.measure(0, 0)
    qc.break_loop().c_if(0, True)

Parameters

  • indexset (Iterable[int(opens in a new tab)]) – A collection of integers to loop over. Always necessary.

  • loop_parameter (Optional[Parameter]) –

    The parameter used within body to which the values from indexset will be assigned. In the context-manager form, if this argument is not supplied, then a loop parameter will be allocated for you and returned as the value of the with statement. This will only be bound into the circuit if it is used within the body.

    If this argument is None in the manual form of this method, body will be repeated once for each of the items in indexset but their values will be ignored.

  • body (Optional[QuantumCircuit]) – The loop body to be repeatedly executed. Omit this to use the context-manager mode.

  • qubits (Optional[Sequence[QubitSpecifier]]) – The circuit qubits over which the loop body should be run. Omit this to use the context-manager mode.

  • clbits (Optional[Sequence[ClbitSpecifier]]) – The circuit clbits over which the loop body should be run. Omit this to use the context-manager mode.

  • label (Optional[str(opens in a new tab)]) – The string label of the instruction in the circuit.

Returns

depending on the call signature, either a context manager for creating the for loop (it will automatically be added to the circuit at the end of the block), or an InstructionSet handle to the appended loop operation.

Return type

InstructionSet or ForLoopContext

Raises

CircuitError – if an incorrect calling convention is used.

from_instructions

static from_instructions(instructions, *, qubits=(), clbits=(), name=None, global_phase=0, metadata=None) GitHub(opens in a new tab)

Construct a circuit from an iterable of CircuitInstructions.

Parameters

Returns

The quantum circuit.

Return type

QuantumCircuit

from_qasm_file

static from_qasm_file(path) GitHub(opens in a new tab)

Read an OpenQASM 2.0 program from a file and convert to an instance of QuantumCircuit.

Parameters

path (str(opens in a new tab)) – Path to the file for an OpenQASM 2 program

Returns

The QuantumCircuit object for the input OpenQASM 2.

Return type

QuantumCircuit

See also

qasm2.load(): the complete interface to the OpenQASM 2 importer.

from_qasm_str

static from_qasm_str(qasm_str) GitHub(opens in a new tab)

Convert a string containing an OpenQASM 2.0 program to a QuantumCircuit.

Parameters

qasm_str (str(opens in a new tab)) – A string containing an OpenQASM 2.0 program.

Returns

The QuantumCircuit object for the input OpenQASM 2

Return type

QuantumCircuit

See also

qasm2.loads(): the complete interface to the OpenQASM 2 importer.

get_instructions

get_instructions(name) GitHub(opens in a new tab)

Get instructions matching name.

Parameters

name (str(opens in a new tab)) – The name of instruction to.

Returns

list of (instruction, qargs, cargs).

Return type

list(opens in a new tab)(tuple(opens in a new tab))

get_parameter

get_parameter(name: str, default: T) → Parameter | T GitHub(opens in a new tab)

get_parameter(name: str, default: ellipsis = Ellipsis) → Parameter

Retrieve a compile-time parameter that is accessible in this circuit scope by name.

Parameters

  • name – the name of the parameter to retrieve.
  • default – if given, this value will be returned if the parameter is not present. If it is not given, a KeyError(opens in a new tab) is raised instead.

Returns

The corresponding parameter.

Raises

KeyError(opens in a new tab) – if no default is given, but the parameter does not exist in the circuit.

Examples

Retrieve a parameter by name from a circuit:

from qiskit.circuit import QuantumCircuit, Parameter
 
my_param = Parameter("my_param")
 
# Create a parametrised circuit.
qc = QuantumCircuit(1)
qc.rx(my_param, 0)
 
# We can use 'my_param' as a parameter, but let's say we've lost the Python object
# and need to retrieve it.
my_param_again = qc.get_parameter("my_param")
 
assert my_param is my_param_again

Get a variable from a circuit by name, returning some default if it is not present:

assert qc.get_parameter("my_param", None) is my_param
assert qc.get_parameter("unknown_param", None) is None

h

h(qubit) GitHub(opens in a new tab)

Apply HGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

qubit (Qubit |QuantumRegister |int(opens in a new tab) |slice(opens in a new tab) |Sequence(opens in a new tab)[Qubit |int(opens in a new tab)]) – The qubit(s) to apply the gate to.

Returns

A handle to the instructions created.

Return type

InstructionSet

has_calibration_for

has_calibration_for(instruction) GitHub(opens in a new tab)

Return True if the circuit has a calibration defined for the instruction context. In this case, the operation does not need to be translated to the device basis.

has_parameter

has_parameter(name_or_param, /) GitHub(opens in a new tab)

Check whether a parameter object exists in this circuit.

Parameters

name_or_param (str(opens in a new tab) |Parameter) – the parameter, or name of a parameter to check. If this is a Parameter node, the parameter must be exactly the given one for this function to return True.

Returns

whether a matching parameter is assignable in this circuit.

Return type

bool(opens in a new tab)

See also

QuantumCircuit.get_parameter()

Retrieve the Parameter instance from this circuit by name.

has_register

has_register(register) GitHub(opens in a new tab)

Test if this circuit has the register r.

Parameters

register (Register) – a quantum or classical register.

Returns

True if the register is contained in this circuit.

Return type

bool(opens in a new tab)

id

id(qubit) GitHub(opens in a new tab)

Apply IGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

qubit (Qubit |QuantumRegister |int(opens in a new tab) |slice(opens in a new tab) |Sequence(opens in a new tab)[Qubit |int(opens in a new tab)]) – The qubit(s) to apply the gate to.

Returns

A handle to the instructions created.

Return type

InstructionSet

if_else

if_else(condition, true_body, false_body, qubits, clbits, label=None) GitHub(opens in a new tab)

Apply IfElseOp.

Note

This method does not have an associated context-manager form, because it is already handled by the if_test() method. You can use the else part of that with something such as:

from qiskit.circuit import QuantumCircuit, Qubit, Clbit
bits = [Qubit(), Qubit(), Clbit()]
qc = QuantumCircuit(bits)
qc.h(0)
qc.cx(0, 1)
qc.measure(0, 0)
with qc.if_test((bits[2], 0)) as else_:
    qc.h(0)
with else_:
    qc.x(0)

Parameters

Raises

CircuitError – If the provided condition references Clbits outside the enclosing circuit.

Returns

A handle to the instruction created.

Return type

InstructionSet

if_test

if_test(condition: tuple[ClassicalRegister | Clbit, int], true_body: None, qubits: None, clbits: None, *, label: str | None) → IfContext GitHub(opens in a new tab)

if_test(condition: tuple[ClassicalRegister | Clbit, int], true_body: QuantumCircuit, qubits: Sequence[Qubit | QuantumRegister | int | slice | Sequence[Qubit | int]], clbits: Sequence[Clbit | ClassicalRegister | int | slice | Sequence[Clbit | int]], *, label: str | None = None) → InstructionSet

Create an if statement on this circuit.

There are two forms for calling this function. If called with all its arguments (with the possible exception of label), it will create a IfElseOp with the given true_body, and there will be no branch for the false condition (see also the if_else() method). However, if true_body (and qubits and clbits) are not passed, then this acts as a context manager, which can be used to build if statements. The return value of the with statement is a chainable context manager, which can be used to create subsequent else blocks. In this form, you do not need to keep track of the qubits or clbits you are using, because the scope will handle it for you.

For example:

from qiskit.circuit import QuantumCircuit, Qubit, Clbit
bits = [Qubit(), Qubit(), Qubit(), Clbit(), Clbit()]
qc = QuantumCircuit(bits)
 
qc.h(0)
qc.cx(0, 1)
qc.measure(0, 0)
qc.h(0)
qc.cx(0, 1)
qc.measure(0, 1)
 
with qc.if_test((bits[3], 0)) as else_:
    qc.x(2)
with else_:
    qc.h(2)
    qc.z(2)

Parameters

  • condition (Tuple[Union[ClassicalRegister, Clbit], int(opens in a new tab)]) – A condition to be evaluated at circuit runtime which, if true, will trigger the evaluation of true_body. Can be specified as either a tuple of a ClassicalRegister to be tested for equality with a given int, or as a tuple of a Clbit to be compared to either a bool or an int.
  • true_body (Optional[QuantumCircuit]) – The circuit body to be run if condition is true.
  • qubits (Optional[Sequence[QubitSpecifier]]) – The circuit qubits over which the if/else should be run.
  • clbits (Optional[Sequence[ClbitSpecifier]]) – The circuit clbits over which the if/else should be run.
  • label (Optional[str(opens in a new tab)]) – The string label of the instruction in the circuit.

Returns

depending on the call signature, either a context manager for creating the if block (it will automatically be added to the circuit at the end of the block), or an InstructionSet handle to the appended conditional operation.

Return type

InstructionSet or IfContext

Raises

  • CircuitError – If the provided condition references Clbits outside the enclosing circuit.
  • CircuitError – if an incorrect calling convention is used.

Returns

A handle to the instruction created.

initialize

initialize(params, qubits=None, normalize=False) GitHub(opens in a new tab)

Initialize qubits in a specific state.

Qubit initialization is done by first resetting the qubits to 0|0\rangle followed by calling StatePreparation class to prepare the qubits in a specified state. Both these steps are included in the Initialize instruction.

Parameters

  • params (Statevector | Sequence[complex(opens in a new tab)] | str(opens in a new tab) |int(opens in a new tab)) –

    The state to initialize to, can be either of the following.

    • Statevector or vector of complex amplitudes to initialize to.
    • Labels of basis states of the Pauli eigenstates Z, X, Y. See Statevector.from_label(). Notice the order of the labels is reversed with respect to the qubit index to be applied to. Example label ‘01’ initializes the qubit zero to 1|1\rangle and the qubit one to 0|0\rangle.
    • An integer that is used as a bitmap indicating which qubits to initialize to 1|1\rangle. Example: setting params to 5 would initialize qubit 0 and qubit 2 to 1|1\rangle and qubit 1 to 0|0\rangle.
  • qubits (Sequence[QubitSpecifier] | None) – Qubits to initialize. If None the initialization is applied to all qubits in the circuit.

  • normalize (bool(opens in a new tab)) – Whether to normalize an input array to a unit vector.

Returns

A handle to the instructions created.

Examples

Prepare a qubit in the state (01)/2(|0\rangle - |1\rangle) / \sqrt{2}.

import numpy as np
from qiskit import QuantumCircuit
 
circuit = QuantumCircuit(1)
circuit.initialize([1/np.sqrt(2), -1/np.sqrt(2)], 0)
circuit.draw()

output:

     ┌──────────────────────────────┐
q_0:Initialize(0.70711,-0.70711)
     └──────────────────────────────┘

Initialize from a string two qubits in the state 10|10\rangle. The order of the labels is reversed with respect to qubit index. More information about labels for basis states are in Statevector.from_label().

import numpy as np
from qiskit import QuantumCircuit
 
circuit = QuantumCircuit(2)
circuit.initialize('01', circuit.qubits)
circuit.draw()

output:

     ┌──────────────────┐
q_0:0
Initialize(0,1)
q_1:1
     └──────────────────┘

Initialize two qubits from an array of complex amplitudes.

import numpy as np
from qiskit import QuantumCircuit
 
circuit = QuantumCircuit(2)
circuit.initialize([0, 1/np.sqrt(2), -1.j/np.sqrt(2), 0], circuit.qubits)
circuit.draw()

output:

     ┌────────────────────────────────────┐
q_0:0
Initialize(0,0.70711,-0.70711j,0)
q_1:1
     └────────────────────────────────────┘

inverse

inverse(annotated=False) GitHub(opens in a new tab)

Invert (take adjoint of) this circuit.

This is done by recursively inverting all gates.

Parameters

annotated (bool(opens in a new tab)) – indicates whether the inverse gate can be implemented as an annotated gate.

Returns

the inverted circuit

Return type

QuantumCircuit

Raises

CircuitError – if the circuit cannot be inverted.

Examples

input:

     ┌───┐
q_0: ┤ H ├─────■──────
     └───┘┌────┴─────┐
q_1: ─────┤ RX(1.57)
          └──────────┘

output:

                  ┌───┐
q_0: ──────■──────┤ H ├
     ┌─────┴─────┐└───┘
q_1:RX(-1.57) ├─────
     └───────────┘

iswap

iswap(qubit1, qubit2) GitHub(opens in a new tab)

Apply iSwapGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

mcp

mcp(lam, control_qubits, target_qubit) GitHub(opens in a new tab)

Apply MCPhaseGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

mcrx

mcrx(theta, q_controls, q_target, use_basis_gates=False) GitHub(opens in a new tab)

Apply Multiple-Controlled X rotation gate

Parameters

Raises

QiskitError – parameter errors

mcry

mcry(theta, q_controls, q_target, q_ancillae=None, mode=None, use_basis_gates=False) GitHub(opens in a new tab)

Apply Multiple-Controlled Y rotation gate

Parameters

Raises

QiskitError – parameter errors

mcrz

mcrz(lam, q_controls, q_target, use_basis_gates=False) GitHub(opens in a new tab)

Apply Multiple-Controlled Z rotation gate

Parameters

Raises

QiskitError – parameter errors

mcx

mcx(control_qubits, target_qubit, ancilla_qubits=None, mode='noancilla') GitHub(opens in a new tab)

Apply MCXGate.

The multi-cX gate can be implemented using different techniques, which use different numbers of ancilla qubits and have varying circuit depth. These modes are:

  • 'noancilla': Requires 0 ancilla qubits.
  • 'recursion': Requires 1 ancilla qubit if more than 4 controls are used, otherwise 0.
  • 'v-chain': Requires 2 less ancillas than the number of control qubits.
  • 'v-chain-dirty': Same as for the clean ancillas (but the circuit will be longer).

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • control_qubits (Sequence[QubitSpecifier]) – The qubits used as the controls.
  • target_qubit (QubitSpecifier) – The qubit(s) targeted by the gate.
  • ancilla_qubits (QubitSpecifier | Sequence[QubitSpecifier] | None) – The qubits used as the ancillae, if the mode requires them.
  • mode (str(opens in a new tab)) – The choice of mode, explained further above.

Returns

A handle to the instructions created.

Raises

Return type

InstructionSet

measure

measure(qubit, cbit) GitHub(opens in a new tab)

Measure a quantum bit (qubit) in the Z basis into a classical bit (cbit).

When a quantum state is measured, a qubit is projected in the computational (Pauli Z) basis to either 0\lvert 0 \rangle or 1\lvert 1 \rangle. The classical bit cbit indicates the result of that projection as a 0 or a 1 respectively. This operation is non-reversible.

Parameters

Returns

handle to the added instructions.

Return type

qiskit.circuit.InstructionSet

Raises

CircuitError – if arguments have bad format.

Examples

In this example, a qubit is measured and the result of that measurement is stored in the classical bit (usually expressed in diagrams as a double line):

from qiskit import QuantumCircuit
circuit = QuantumCircuit(1, 1)
circuit.h(0)
circuit.measure(0, 0)
circuit.draw()
     ┌───┐┌─┐
  q: ┤ H ├┤M├
     └───┘└╥┘
c: 1/══════╩═
           0

It is possible to call measure with lists of qubits and cbits as a shortcut for one-to-one measurement. These two forms produce identical results:

circuit = QuantumCircuit(2, 2)
circuit.measure([0,1], [0,1])
circuit = QuantumCircuit(2, 2)
circuit.measure(0, 0)
circuit.measure(1, 1)

Instead of lists, you can use QuantumRegister and ClassicalRegister under the same logic.

from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister
qreg = QuantumRegister(2, "qreg")
creg = ClassicalRegister(2, "creg")
circuit = QuantumCircuit(qreg, creg)
circuit.measure(qreg, creg)

This is equivalent to:

circuit = QuantumCircuit(qreg, creg)
circuit.measure(qreg[0], creg[0])
circuit.measure(qreg[1], creg[1])

measure_active

measure_active(inplace=True) GitHub(opens in a new tab)

Adds measurement to all non-idle qubits. Creates a new ClassicalRegister with a size equal to the number of non-idle qubits being measured.

Returns a new circuit with measurements if inplace=False.

Parameters

inplace (bool(opens in a new tab)) – All measurements inplace or return new circuit.

Returns

Returns circuit with measurements when inplace = False.

Return type

QuantumCircuit

measure_all

measure_all(inplace=True, add_bits=True) GitHub(opens in a new tab)

Adds measurement to all qubits.

By default, adds new classical bits in a ClassicalRegister to store these measurements. If add_bits=False, the results of the measurements will instead be stored in the already existing classical bits, with qubit n being measured into classical bit n.

Returns a new circuit with measurements if inplace=False.

Parameters

Returns

Returns circuit with measurements when inplace=False.

Return type

QuantumCircuit

Raises

CircuitError – if add_bits=False but there are not enough classical bits.

ms

ms(theta, qubits) GitHub(opens in a new tab)

Apply MSGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

num_connected_components

num_connected_components(unitary_only=False) GitHub(opens in a new tab)

How many non-entangled subcircuits can the circuit be factored to.

Parameters

unitary_only (bool(opens in a new tab)) – Compute only unitary part of graph.

Returns

Number of connected components in circuit.

Return type

int(opens in a new tab)

num_nonlocal_gates

num_nonlocal_gates() GitHub(opens in a new tab)

Return number of non-local gates (i.e. involving 2+ qubits).

Conditional nonlocal gates are also included.

Return type

int(opens in a new tab)

num_tensor_factors

num_tensor_factors() GitHub(opens in a new tab)

Computes the number of tensor factors in the unitary (quantum) part of the circuit only.

Notes

This is here for backwards compatibility, and will be removed in a future release of Qiskit. You should call num_unitary_factors instead.

Return type

int(opens in a new tab)

num_unitary_factors

num_unitary_factors() GitHub(opens in a new tab)

Computes the number of tensor factors in the unitary (quantum) part of the circuit only.

Return type

int(opens in a new tab)

p

p(theta, qubit) GitHub(opens in a new tab)

Apply PhaseGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

pauli

pauli(pauli_string, qubits) GitHub(opens in a new tab)

Apply PauliGate.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

power

power(power, matrix_power=False) GitHub(opens in a new tab)

Raise this circuit to the power of power.

If power is a positive integer and matrix_power is False, this implementation defaults to calling repeat. Otherwise, if the circuit is unitary, the matrix is computed to calculate the matrix power.

Parameters

  • power (float(opens in a new tab)) – The power to raise this circuit to.
  • matrix_power (bool(opens in a new tab)) – If True, the circuit is converted to a matrix and then the matrix power is computed. If False, and power is a positive integer, the implementation defaults to repeat.

Raises

CircuitError – If the circuit needs to be converted to a gate but it is not unitary.

Returns

A circuit implementing this circuit raised to the power of power.

Return type

QuantumCircuit

prepare_state

prepare_state(state, qubits=None, label=None, normalize=False) GitHub(opens in a new tab)

Prepare qubits in a specific state.

This class implements a state preparing unitary. Unlike initialize() it does not reset the qubits first.

Parameters

  • state (Statevector | Sequence[complex(opens in a new tab)] | str(opens in a new tab) |int(opens in a new tab)) –

    The state to initialize to, can be either of the following.

    • Statevector or vector of complex amplitudes to initialize to.
    • Labels of basis states of the Pauli eigenstates Z, X, Y. See Statevector.from_label(). Notice the order of the labels is reversed with respect to the qubit index to be applied to. Example label ‘01’ initializes the qubit zero to 1|1\rangle and the qubit one to 0|0\rangle.
    • An integer that is used as a bitmap indicating which qubits to initialize to 1|1\rangle. Example: setting params to 5 would initialize qubit 0 and qubit 2 to 1|1\rangle and qubit 1 to 0|0\rangle.
  • qubits (Sequence[QubitSpecifier] | None) – Qubits to initialize. If None the initialization is applied to all qubits in the circuit.

  • label (str(opens in a new tab) | None) – An optional label for the gate

  • normalize (bool(opens in a new tab)) – Whether to normalize an input array to a unit vector.

Returns

A handle to the instruction that was just initialized

Return type

InstructionSet

Examples

Prepare a qubit in the state (01)/2(|0\rangle - |1\rangle) / \sqrt{2}.

import numpy as np
from qiskit import QuantumCircuit
 
circuit = QuantumCircuit(1)
circuit.prepare_state([1/np.sqrt(2), -1/np.sqrt(2)], 0)
circuit.draw()

output:

     ┌─────────────────────────────────────┐
q_0: ┤ State Preparation(0.70711,-0.70711)
     └─────────────────────────────────────┘

Prepare from a string two qubits in the state 10|10\rangle. The order of the labels is reversed with respect to qubit index. More information about labels for basis states are in Statevector.from_label().

import numpy as np
from qiskit import QuantumCircuit
 
circuit = QuantumCircuit(2)
circuit.prepare_state('01', circuit.qubits)
circuit.draw()

output:

     ┌─────────────────────────┐
q_0:0
     │  State Preparation(0,1)
q_1:1
     └─────────────────────────┘

Initialize two qubits from an array of complex amplitudes .. code-block:

import numpy as np
from qiskit import QuantumCircuit
 
circuit = QuantumCircuit(2)
circuit.prepare_state([0, 1/np.sqrt(2), -1.j/np.sqrt(2), 0], circuit.qubits)
circuit.draw()

output:

     ┌───────────────────────────────────────────┐
q_0:0
     │  State Preparation(0,0.70711,-0.70711j,0)
q_1:1
     └───────────────────────────────────────────┘

qbit_argument_conversion

qbit_argument_conversion(qubit_representation) GitHub(opens in a new tab)

Converts several qubit representations (such as indexes, range, etc.) into a list of qubits.

Parameters

qubit_representation (Object) – representation to expand

Returns

the resolved instances of the qubits.

Return type

List(Qubit)

qubit_duration

qubit_duration(*qubits) GitHub(opens in a new tab)

Return the duration between the start and stop time of the first and last instructions, excluding delays, over the supplied qubits. Its time unit is self.unit.

Parameters

*qubits (Qubit |int(opens in a new tab)) – Qubits within self to include.

Returns

Return the duration between the first start and last stop time of non-delay instructions

Return type

float(opens in a new tab)

qubit_start_time

qubit_start_time(*qubits) GitHub(opens in a new tab)

Return the start time of the first instruction, excluding delays, over the supplied qubits. Its time unit is self.unit.

Return 0 if there are no instructions over qubits

Parameters

  • *qubits (Qubit |int(opens in a new tab)) – Qubits within self to include. Integers are allowed for qubits, indicating
  • self.qubits. (indices of) –

Returns

Return the start time of the first instruction, excluding delays, over the qubits

Raises

CircuitError – if self is a not-yet scheduled circuit.

Return type

float(opens in a new tab)

qubit_stop_time

qubit_stop_time(*qubits) GitHub(opens in a new tab)

Return the stop time of the last instruction, excluding delays, over the supplied qubits. Its time unit is self.unit.

Return 0 if there are no instructions over qubits

Parameters

  • *qubits (Qubit |int(opens in a new tab)) – Qubits within self to include. Integers are allowed for qubits, indicating
  • self.qubits. (indices of) –

Returns

Return the stop time of the last instruction, excluding delays, over the qubits

Raises

CircuitError – if self is a not-yet scheduled circuit.

Return type

float(opens in a new tab)

r

r(theta, phi, qubit) GitHub(opens in a new tab)

Apply RGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

rcccx

rcccx(control_qubit1, control_qubit2, control_qubit3, target_qubit) GitHub(opens in a new tab)

Apply RC3XGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

rccx

rccx(control_qubit1, control_qubit2, target_qubit) GitHub(opens in a new tab)

Apply RCCXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

remove_final_measurements

remove_final_measurements(inplace=True) GitHub(opens in a new tab)

Removes final measurements and barriers on all qubits if they are present. Deletes the classical registers that were used to store the values from these measurements that become idle as a result of this operation, and deletes classical bits that are referenced only by removed registers, or that aren’t referenced at all but have become idle as a result of this operation.

Measurements and barriers are considered final if they are followed by no other operations (aside from other measurements or barriers.)

Parameters

inplace (bool(opens in a new tab)) – All measurements removed inplace or return new circuit.

Returns

Returns the resulting circuit when inplace=False, else None.

Return type

QuantumCircuit

repeat

repeat(reps) GitHub(opens in a new tab)

Repeat this circuit reps times.

Parameters

reps (int(opens in a new tab)) – How often this circuit should be repeated.

Returns

A circuit containing reps repetitions of this circuit.

Return type

QuantumCircuit

reset

reset(qubit) GitHub(opens in a new tab)

Reset the quantum bit(s) to their default state.

Parameters

qubit (Qubit |QuantumRegister |int(opens in a new tab) |slice(opens in a new tab) |Sequence(opens in a new tab)[Qubit |int(opens in a new tab)]) – qubit(s) to reset.

Returns

handle to the added instruction.

Return type

qiskit.circuit.InstructionSet

reverse_bits

reverse_bits() GitHub(opens in a new tab)

Return a circuit with the opposite order of wires.

The circuit is “vertically” flipped. If a circuit is defined over multiple registers, the resulting circuit will have the same registers but with their order flipped.

This method is useful for converting a circuit written in little-endian convention to the big-endian equivalent, and vice versa.

Returns

the circuit with reversed bit order.

Return type

QuantumCircuit

Examples

input:

     ┌───┐
a_0: ┤ H ├──■─────────────────
     └───┘┌─┴─┐
a_1: ─────┤ X ├──■────────────
          └───┘┌─┴─┐
a_2: ──────────┤ X ├──■───────
               └───┘┌─┴─┐
b_0: ───────────────┤ X ├──■──
                    └───┘┌─┴─┐
b_1: ────────────────────┤ X ├
                         └───┘

output:

                         ┌───┐
b_0: ────────────────────┤ X ├
                    ┌───┐└─┬─┘
b_1: ───────────────┤ X ├──■──
               ┌───┐└─┬─┘
a_0: ──────────┤ X ├──■───────
          ┌───┐└─┬─┘
a_1: ─────┤ X ├──■────────────
     ┌───┐└─┬─┘
a_2: ┤ H ├──■─────────────────
     └───┘

reverse_ops

reverse_ops() GitHub(opens in a new tab)

Reverse the circuit by reversing the order of instructions.

This is done by recursively reversing all instructions. It does not invert (adjoint) any gate.

Returns

the reversed circuit.

Return type

QuantumCircuit

Examples

input:

     ┌───┐
q_0: ┤ H ├─────■──────
     └───┘┌────┴─────┐
q_1: ─────┤ RX(1.57)
          └──────────┘

output:

                 ┌───┐
q_0: ─────■──────┤ H ├
     ┌────┴─────┐└───┘
q_1:RX(1.57) ├─────
     └──────────┘

rv

rv(vx, vy, vz, qubit) GitHub(opens in a new tab)

Apply RVGate.

For the full matrix form of this gate, see the underlying gate documentation.

Rotation around an arbitrary rotation axis vv, where v|v| is the angle of rotation in radians.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

rx

rx(theta, qubit, label=None) GitHub(opens in a new tab)

Apply RXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • theta (ParameterValueType) – The rotation angle of the gate.
  • qubit (QubitSpecifier) – The qubit(s) to apply the gate to.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.

Returns

A handle to the instructions created.

Return type

InstructionSet

rxx

rxx(theta, qubit1, qubit2) GitHub(opens in a new tab)

Apply RXXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

ry

ry(theta, qubit, label=None) GitHub(opens in a new tab)

Apply RYGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

  • theta (ParameterValueType) – The rotation angle of the gate.
  • qubit (QubitSpecifier) – The qubit(s) to apply the gate to.
  • label (str(opens in a new tab) | None) – The string label of the gate in the circuit.

Returns

A handle to the instructions created.

Return type

InstructionSet

ryy

ryy(theta, qubit1, qubit2) GitHub(opens in a new tab)

Apply RYYGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

rz

rz(phi, qubit) GitHub(opens in a new tab)

Apply RZGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

rzx

rzx(theta, qubit1, qubit2) GitHub(opens in a new tab)

Apply RZXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

rzz

rzz(theta, qubit1, qubit2) GitHub(opens in a new tab)

Apply RZZGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

s

s(qubit) GitHub(opens in a new tab)

Apply SGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

qubit (Qubit |QuantumRegister |int(opens in a new tab) |slice(opens in a new tab) |Sequence(opens in a new tab)[Qubit |int(opens in a new tab)]) – The qubit(s) to apply the gate to.

Returns

A handle to the instructions created.

Return type

InstructionSet

sdg

sdg(qubit) GitHub(opens in a new tab)

Apply SdgGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

qubit (Qubit |QuantumRegister |int(opens in a new tab) |slice(opens in a new tab) |Sequence(opens in a new tab)[Qubit |int(opens in a new tab)]) – The qubit(s) to apply the gate to.

Returns

A handle to the instructions created.

Return type

InstructionSet

size

size(filter_function=<function QuantumCircuit.<lambda>>) GitHub(opens in a new tab)

Returns total number of instructions in circuit.

Parameters

filter_function (callable) – a function to filter out some instructions. Should take as input a tuple of (Instruction, list(Qubit), list(Clbit)). By default filters out “directives”, such as barrier or snapshot.

Returns

Total number of gate operations.

Return type

int(opens in a new tab)

swap

swap(qubit1, qubit2) GitHub(opens in a new tab)

Apply SwapGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

switch

switch(target: Clbit | ClassicalRegister | int | slice | Sequence[Clbit | int], cases: None, qubits: None, clbits: None, *, label: str | None) → SwitchContext GitHub(opens in a new tab)

switch(target: Clbit | ClassicalRegister | int | slice | Sequence[Clbit | int], cases: Iterable[Tuple[Any, QuantumCircuit]], qubits: Sequence[Qubit | QuantumRegister | int | slice | Sequence[Qubit | int]], clbits: Sequence[Clbit | ClassicalRegister | int | slice | Sequence[Clbit | int]], *, label: str | None) → InstructionSet

Create a switch/case structure on this circuit.

There are two forms for calling this function. If called with all its arguments (with the possible exception of label), it will create a SwitchCaseOp with the given case structure. If cases (and qubits and clbits) are not passed, then this acts as a context manager, which will automatically build a SwitchCaseOp when the scope finishes. In this form, you do not need to keep track of the qubits or clbits you are using, because the scope will handle it for you.

Example usage:

from qiskit.circuit import QuantumCircuit, ClassicalRegister, QuantumRegister
qreg = QuantumRegister(3)
creg = ClassicalRegister(3)
qc = QuantumCircuit(qreg, creg)
qc.h([0, 1, 2])
qc.measure([0, 1, 2], [0, 1, 2])
 
with qc.switch(creg) as case:
    with case(0):
        qc.x(0)
    with case(1, 2):
        qc.z(1)
    with case(case.DEFAULT):
        qc.cx(0, 1)

Parameters

  • target (Union[ClassicalRegister, Clbit]) – The classical value to switch one. This must be integer-like.
  • cases (Iterable[Tuple[Any(opens in a new tab), QuantumCircuit]]) – A sequence of case specifiers. Each tuple defines one case body (the second item). The first item of the tuple can be either a single integer value, the special value CASE_DEFAULT, or a tuple of several integer values. Each of the integer values will be tried in turn; control will then pass to the body corresponding to the first match. CASE_DEFAULT matches all possible values. Omit in context-manager form.
  • qubits (Sequence[Qubit]) – The circuit qubits over which all case bodies execute. Omit in context-manager form.
  • clbits (Sequence[Clbit]) – The circuit clbits over which all case bodies execute. Omit in context-manager form.
  • label (Optional[str(opens in a new tab)]) – The string label of the instruction in the circuit.

Returns

If used in context-manager mode, then this should be used as a with resource, which will return an object that can be repeatedly entered to produce cases for the switch statement. If the full form is used, then this returns a handle to the instructions created.

Return type

InstructionSet or SwitchCaseContext

Raises

CircuitError – if an incorrect calling convention is used.

sx

sx(qubit) GitHub(opens in a new tab)

Apply SXGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

qubit (Qubit |QuantumRegister |int(opens in a new tab) |slice(opens in a new tab) |Sequence(opens in a new tab)[Qubit |int(opens in a new tab)]) – The qubit(s) to apply the gate to.

Returns

A handle to the instructions created.

Return type

InstructionSet

sxdg

sxdg(qubit) GitHub(opens in a new tab)

Apply SXdgGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

qubit (Qubit |QuantumRegister |int(opens in a new tab) |slice(opens in a new tab) |Sequence(opens in a new tab)[Qubit |int(opens in a new tab)]) – The qubit(s) to apply the gate to.

Returns

A handle to the instructions created.

Return type

InstructionSet

t

t(qubit) GitHub(opens in a new tab)

Apply TGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

qubit (Qubit |QuantumRegister |int(opens in a new tab) |slice(opens in a new tab) |Sequence(opens in a new tab)[Qubit |int(opens in a new tab)]) – The qubit(s) to apply the gate to.

Returns

A handle to the instructions created.

Return type

InstructionSet

tdg

tdg(qubit) GitHub(opens in a new tab)

Apply TdgGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

qubit (Qubit |QuantumRegister |int(opens in a new tab) |slice(opens in a new tab) |Sequence(opens in a new tab)[Qubit |int(opens in a new tab)]) – The qubit(s) to apply the gate to.

Returns

A handle to the instructions created.

Return type

InstructionSet

tensor

tensor(other, inplace=False) GitHub(opens in a new tab)

Tensor self with other.

Remember that in the little-endian convention the leftmost operation will be at the bottom of the circuit. See also the docs for more information.

     ┌────────┐        ┌─────┐          ┌─────┐
q_0: ┤ bottom ├ ⊗ q_0: ┤ top ├  = q_0: ─┤ top ├──
     └────────┘        └─────┘         ┌┴─────┴─┐
                                  q_1: ┤ bottom ├
                                       └────────┘

Parameters

Return type

QuantumCircuit | None

Examples

from qiskit import QuantumCircuit
top = QuantumCircuit(1)
top.x(0);
bottom = QuantumCircuit(2)
bottom.cry(0.2, 0, 1);
tensored = bottom.tensor(top)
tensored.draw('mpl')
../_images/qiskit-circuit-QuantumCircuit-6.png

Returns

The tensored circuit (returns None if inplace==True).

Return type

QuantumCircuit

to_gate

to_gate(parameter_map=None, label=None) GitHub(opens in a new tab)

Create a Gate out of this circuit.

Parameters

  • parameter_map (dict(opens in a new tab)) – For parameterized circuits, a mapping from parameters in the circuit to parameters to be used in the gate. If None, existing circuit parameters will also parameterize the gate.
  • label (str(opens in a new tab)) – Optional gate label.

Returns

a composite gate encapsulating this circuit (can be decomposed back)

Return type

Gate

to_instruction

to_instruction(parameter_map=None, label=None) GitHub(opens in a new tab)

Create an Instruction out of this circuit.

Parameters

  • parameter_map (dict(opens in a new tab)) – For parameterized circuits, a mapping from parameters in the circuit to parameters to be used in the instruction. If None, existing circuit parameters will also parameterize the instruction.
  • label (str(opens in a new tab)) – Optional gate label.

Returns

a composite instruction encapsulating this circuit (can be decomposed back)

Return type

qiskit.circuit.Instruction

u

u(theta, phi, lam, qubit) GitHub(opens in a new tab)

Apply UGate.

For the full matrix form of this gate, see the underlying gate documentation.

Parameters

Returns

A handle to the instructions created.

Return type

InstructionSet

unitary

unitary(obj, qubits, label=None) GitHub(opens in a new tab)

Apply unitary gate specified by obj to qubits.

Parameters

  • obj (np.ndarray | Gate | BaseOperator) – Unitary operator.
  • qubits (Sequence[QubitSpecifier]) – The circuit qubits to apply the transformation to.
  • label (str(opens in a new tab) | None) – Unitary name for backend [Default: None].

Returns

The quantum circuit.

Return type

QuantumCircuit

Example

Apply a gate specified by a unitary matrix to a quantum circuit

from qiskit import QuantumCircuit
matrix = [[0, 0, 0, 1],
        [0, 0, 1, 0],
        [1, 0, 0, 0],
        [0, 1, 0, 0]]
circuit = QuantumCircuit(2)
circuit.unitary(matrix, [0, 1])

while_loop

while_loop(condition: tuple[ClassicalRegister | Clbit, int] | expr.Expr, body: None, qubits: None, clbits: None, *, label: str | None) → WhileLoopContext GitHub(opens in a new tab)

while_loop(condition: tuple[ClassicalRegister | Clbit, int] | expr.Expr, body: QuantumCircuit, qubits: Sequence[Qubit | QuantumRegister | int | slice | Sequence[Qubit | int]], clbits: Sequence[Clbit | ClassicalRegister | int | slice | Sequence[Clbit | int]], *, label: str | None) → InstructionSet

Create a while loop on this circuit.

There are two forms for calling this function. If called with all its arguments (with the possible exception of label), it will create a WhileLoopOp with the given body. If body (and qubits and clbits) are not passed, then this acts as a context manager, which will automatically build a WhileLoopOp when the scope finishes. In this form, you do not need to keep track of the qubits or clbits you are using, because the scope will handle it for you.

Example usage:

from qiskit.circuit import QuantumCircuit, Clbit, Qubit
bits = [Qubit(), Qubit(), Clbit()]
qc = QuantumCircuit(bits)
 
with qc.while_loop((bits[2], 0)):
    qc.h(0)
    qc.cx(0, 1)
    qc.measure(0, 0)

Parameters

  • condition (Tuple[Union[ClassicalRegister, Clbit], int(opens in a new tab)]) – An equality condition to be checked prior to executing body. The left-hand side of the condition must be a ClassicalRegister or a Clbit, and the right-hand side must be an integer or boolean.
  • body (Optional[QuantumCircuit]) – The loop body to be repeatedly executed. Omit this to use the context-manager mode.
  • qubits (Optional[Sequence[Qubit]]) – The circuit qubits over which the loop body should be run. Omit this to use the context-manager mode.
  • clbits (Optional[Sequence[Clbit]]) – The circuit clbits over which the loop body should be run. Omit this to use the context-manager mode.
  • label (Optional[str(opens in a new tab)]) – The string label of the instruction in the circuit.

Returns

If used in context-manager mode, then this should be used as a with resource, which will infer the block content and operands on exit. If the full form is used, then this returns a handle to the instructions created.

Return type

InstructionSet or WhileLoopContext

Raises

CircuitError – if an incorrect calling convention is used.