PiecewiseLinearPauliRotations

class qiskit.circuit.library.PiecewiseLinearPauliRotations(num_state_qubits=None, breakpoints=None, slopes=None, offsets=None, basis='Y', name='pw_lin')

GitHub

Bases: FunctionalPauliRotations

Piecewise-linearly-controlled Pauli rotations.

For a piecewise linear (not necessarily continuous) function $f(x)$ , which is defined through breakpoints, slopes and offsets as follows. Suppose the breakpoints $(x_0, ..., x_J)$ are a subset of $[0, 2^n-1]$ , where $n$ is the number of state qubits. Further on, denote the corresponding slopes and offsets by $a_j$ and $b_j$ respectively. Then f(x) is defined as:

f(x) = \begin{cases} 0, x < x_0 \\ a_j (x - x_j) + b_j, x_j \leq x < x_{j+1} \end{cases}

where we implicitly assume $x_{J+1} = 2^n$ .

Construct piecewise-linearly-controlled Pauli rotations.

Parameters

num_state_qubits (int | None) – The number of qubits representing the state.
breakpoints (list[int] | None) – The breakpoints to define the piecewise-linear function. Defaults to [0].
slopes (list[float] | np.ndarray | None) – The slopes for different segments of the piecewise-linear function. Defaults to [1].
offsets (list[float] | np.ndarray | None) – The offsets for different segments of the piecewise-linear function. Defaults to [0].
basis (str) – The type of Pauli rotation ('X', 'Y', 'Z').
name (str) – The name of the circuit.

Attributes

ancillas

A list of AncillaQubits in the order that they were added. You should not mutate this.

basis

The kind of Pauli rotation to be used.

Set the basis to ‘X’, ‘Y’ or ‘Z’ for controlled-X, -Y, or -Z rotations respectively.

Returns

The kind of Pauli rotation used in controlled rotation.

breakpoints

The breakpoints of the piecewise linear function.

The function is linear in the intervals [point_i, point_{i+1}] where the last point implicitly is 2**(num_state_qubits + 1).

calibrations

Return calibration dictionary.

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

clbits

A list of Clbits in the order that they were added. You should not mutate this.

contains_zero_breakpoint

Whether 0 is the first breakpoint.

Returns

True, if 0 is the first breakpoint, otherwise False.

data

The circuit data (instructions and context).

Returns

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

Return type

QuantumCircuitData

global_phase

The global phase of the current circuit scope in radians.

instances

Default value: 323

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.

mapped_offsets

The offsets mapped to the internal representation.

Returns

The mapped offsets.

mapped_slopes

The slopes mapped to the internal representation.

Returns

The mapped slopes.

metadata

Arbitrary user-defined metadata for the circuit.

Qiskit will not examine the content of this mapping, but it will pass it through the transpiler and reattach it to the output, so you can track your own metadata.

num_ancilla_qubits

The minimum number of ancilla qubits in the circuit.

Returns

The minimal number of ancillas required.

num_ancillas

Return the number of ancilla qubits.

num_captured_vars

The number of real-time classical variables in the circuit marked as captured from an enclosing scope.

This is the length of the iter_captured_vars() iterable. If this is non-zero, num_input_vars must be zero.

num_clbits

Return number of classical bits.

num_declared_vars

The number of real-time classical variables in the circuit that are declared by this circuit scope, excluding inputs or captures.

This is the length of the iter_declared_vars() iterable.

num_input_vars

The number of real-time classical variables in the circuit marked as circuit inputs.

This is the length of the iter_input_vars() iterable. If this is non-zero, num_captured_vars must be zero.

num_parameters

The number of parameter objects in the circuit.

num_qubits

Return number of qubits.

num_state_qubits

The number of state qubits representing the state $|x\rangle$ .

Returns

The number of state qubits.

num_vars

The number of real-time classical variables in the circuit.

This is the length of the iter_vars() iterable.

offsets

The breakpoints of the piecewise linear function.

The function is linear in the intervals [point_i, point_{i+1}] where the last point implicitly is 2**(num_state_qubits + 1).

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 – 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

Default value: 'circuit'

qregs

Type: list[QuantumRegister]

A list of the QuantumRegisters in this circuit. You should not mutate this.

qubits

A list of Qubits in the order that they were added. You should not mutate this.

slopes

The breakpoints of the piecewise linear function.

The function is linear in the intervals [point_i, point_{i+1}] where the last point implicitly is 2**(num_state_qubits + 1).

name

Type: str

A human-readable name for the circuit.

cregs

Type: list[ClassicalRegister]

A list of the ClassicalRegisters in this circuit. You should not mutate this.

duration

Type: int | float | None

The total duration of the circuit, set by a scheduling transpiler pass. Its unit is specified by unit.

unit

The unit that duration is specified in.

Methods

evaluate

evaluate(x)

GitHub

Classically evaluate the piecewise linear rotation.

Parameters

x (float) – Value to be evaluated at.

Returns

Value of piecewise linear function at x.

Return type

float

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