PiecewiseLinearPauliRotations

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

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

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

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

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

contains_zero_breakpoint

Whether 0 is the first breakpoint.

Returns:

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

data

extension_lib = 'include "qelib1.inc";'

global_phase

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

header = 'OPENQASM 2.0;'

instances = 328

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

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_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_clbits

Return number of classical bits.

num_parameters

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.

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

prefix = 'circuit'

qregs: list[QuantumRegister]

A list of the quantum registers associated with the circuit.

qubits

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

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).

Methods

evaluate(x)

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