qiskit.circuit.library.CSwapGate
class CSwapGate(label=None, ctrl_state=None)
Controlled-X gate.
Circuit symbol:
q_0: ─X─
│
q_1: ─X─
│
q_2: ─■─Matrix representation:
In Qiskit’s convention, higher qubit indices are more significant (little endian convention). In many textbooks, controlled gates are presented with the assumption of more significant qubits as control, which in our case would be q_2. Thus a textbook matrix for this gate will be:
q_0: ─■─
│
q_1: ─X─
│
q_2: ─X─In the computational basis, this gate swaps the states of the two target qubits if the control qubit is in the state.
Create new CSWAP gate.
__init__
__init__(label=None, ctrl_state=None)
Create new CSWAP gate.
Methods
__init__([label, ctrl_state]) | Create new CSWAP gate. |
add_decomposition(decomposition) | Add a decomposition of the instruction to the SessionEquivalenceLibrary. |
assemble() | Assemble a QasmQobjInstruction |
broadcast_arguments(qargs, cargs) | Validation and handling of the arguments and its relationship. |
c_if(classical, val) | Add classical condition on register classical and value val. |
control([num_ctrl_qubits, label, ctrl_state]) | Return controlled version of gate. |
copy([name]) | Copy of the instruction. |
inverse() | Return inverse CSwap gate (itself). |
is_parameterized() | Return True .IFF. |
mirror() | DEPRECATED: use instruction.reverse_ops(). |
power(exponent) | Creates a unitary gate as gate^exponent. |
qasm() | Return a default OpenQASM string for the instruction. |
repeat(n) | Creates an instruction with gate repeated n amount of times. |
reverse_ops() | For a composite instruction, reverse the order of sub-instructions. |
to_matrix() | Return a numpy.array for the Fredkin (CSWAP) gate. |
validate_parameter(parameter) | Gate parameters should be int, float, or ParameterExpression |
Attributes
ctrl_state | Return the control state of the gate as a decimal integer. |
decompositions | Get the decompositions of the instruction from the SessionEquivalenceLibrary. |
definition | Return definition in terms of other basic gates. |
duration | Get the duration. |
label | Return gate label |
num_ctrl_qubits | Get number of control qubits. |
params | Get parameters from base_gate. |
unit | Get the time unit of duration. |
add_decomposition
add_decomposition(decomposition)
Add a decomposition of the instruction to the SessionEquivalenceLibrary.
assemble
assemble()
Assemble a QasmQobjInstruction
Return type
Instruction
broadcast_arguments
broadcast_arguments(qargs, cargs)
Validation and handling of the arguments and its relationship.
For example, cx([q[0],q[1]], q[2]) means cx(q[0], q[2]); cx(q[1], q[2]). This method yields the arguments in the right grouping. In the given example:
in: [[q[0],q[1]], q[2]],[]
outs: [q[0], q[2]], []
[q[1], q[2]], []The general broadcasting rules are:
If len(qargs) == 1:
[q[0], q[1]] -> [q[0]],[q[1]]If len(qargs) == 2:
[[q[0], q[1]], [r[0], r[1]]] -> [q[0], r[0]], [q[1], r[1]] [[q[0]], [r[0], r[1]]] -> [q[0], r[0]], [q[0], r[1]] [[q[0], q[1]], [r[0]]] -> [q[0], r[0]], [q[1], r[0]]If len(qargs) >= 3:
[q[0], q[1]], [r[0], r[1]], ...] -> [q[0], r[0], ...], [q[1], r[1], ...]
Parameters
- qargs (
List) – List of quantum bit arguments. - cargs (
List) – List of classical bit arguments.
Return type
Tuple[List, List]
Returns
A tuple with single arguments.
Raises
CircuitError – If the input is not valid. For example, the number of arguments does not match the gate expectation.
c_if
c_if(classical, val)
Add classical condition on register classical and value val.
control
control(num_ctrl_qubits=1, label=None, ctrl_state=None)
Return controlled version of gate. See ControlledGate for usage.
Parameters
- num_ctrl_qubits (
Optional[int]) – number of controls to add to gate (default=1) - label (
Optional[str]) – optional gate label - ctrl_state (
Union[int,str,None]) – The control state in decimal or as a bitstring (e.g. ‘111’). If None, use 2**num_ctrl_qubits-1.
Returns
Controlled version of gate. This default algorithm uses num_ctrl_qubits-1 ancillae qubits so returns a gate of size num_qubits + 2*num_ctrl_qubits - 1.
Return type
Raises
QiskitError – unrecognized mode or invalid ctrl_state
copy
copy(name=None)
Copy of the instruction.
Parameters
name (str) – name to be given to the copied circuit, if None then the name stays the same.
Returns
a copy of the current instruction, with the name
updated if it was provided
Return type
ctrl_state
Return the control state of the gate as a decimal integer.
Return type
int
decompositions
Get the decompositions of the instruction from the SessionEquivalenceLibrary.
definition
Return definition in terms of other basic gates. If the gate has open controls, as determined from self.ctrl_state, the returned definition is conjugated with X without changing the internal _definition.
Return type
List
duration
Get the duration.
inverse
inverse()
Return inverse CSwap gate (itself).
is_parameterized
is_parameterized()
Return True .IFF. instruction is parameterized else False
label
Return gate label
Return type
str
mirror
mirror()
DEPRECATED: use instruction.reverse_ops().
Returns
a new instruction with sub-instructions
reversed.
Return type
num_ctrl_qubits
Get number of control qubits.
Returns
The number of control qubits for the gate.
Return type
int
params
Get parameters from base_gate.
Returns
List of gate parameters.
Return type
list
Raises
CircuitError – Controlled gate does not define a base gate
power
power(exponent)
Creates a unitary gate as gate^exponent.
Parameters
exponent (float) – Gate^exponent
Returns
To which to_matrix is self.to_matrix^exponent.
Return type
Raises
CircuitError – If Gate is not unitary
qasm
qasm()
Return a default OpenQASM string for the instruction.
Derived instructions may override this to print in a different format (e.g. measure q[0] -> c[0];).
repeat
repeat(n)
Creates an instruction with gate repeated n amount of times.
Parameters
n (int) – Number of times to repeat the instruction
Returns
Containing the definition.
Return type
Raises
CircuitError – If n < 1.
reverse_ops
reverse_ops()
For a composite instruction, reverse the order of sub-instructions.
This is done by recursively reversing all sub-instructions. It does not invert any gate.
Returns
a new instruction with
sub-instructions reversed.
Return type
to_matrix
to_matrix()
Return a numpy.array for the Fredkin (CSWAP) gate.
unit
Get the time unit of duration.
validate_parameter
validate_parameter(parameter)
Gate parameters should be int, float, or ParameterExpression