LinearFunction¶
- class LinearFunction(linear, validate_input=False)[source]¶
Bases:
qiskit.circuit.gate.Gate
A linear reversible circuit on n qubits.
Internally, a linear function acting on n qubits is represented as a n x n matrix of 0s and 1s in numpy array format.
A linear function can be synthesized into CX and SWAP gates using the Patel–Markov–Hayes algorithm, as implemented in
cnot_synth()
based on reference [1].For efficiency, the internal n x n matrix is stored in the format expected by cnot_synth, which is the big-endian (and not the little-endian) bit-ordering convention.
Example: the circuit
q_0: ──■── ┌─┴─┐ q_1: ┤ X ├ └───┘ q_2: ─────
is represented by a 3x3 linear matrix
\[\begin{split}\begin{pmatrix} 1 & 0 & 0 \\ 1 & 1 & 0 \\ 0 & 0 & 1 \end{pmatrix}\end{split}\]References:
[1] Ketan N. Patel, Igor L. Markov, and John P. Hayes, Optimal synthesis of linear reversible circuits, Quantum Inf. Comput. 8(3) (2008). Online at umich.edu.
Create a new linear function.
- Parameters
linear (list[list] or ndarray[bool] or QuantumCircuit) – either an n x n matrix, describing the linear function, or a quantum circuit composed of linear gates only (currently supported gates are CX and SWAP).
validate_input (
Optional
[bool
]) – if True, performs more expensive input validation checks, such as checking that a given n x n matrix is invertible.
- Raises
CircuitError – if the input is invalid: either a matrix is non {square, invertible}, or a quantum circuit contains non-linear gates.
Methods Defined Here
Returns whether this linear function is a permutation, that is whether every row and every column of the n x n matrix has exactly one 1.
This method first checks if a linear function is a permutation and raises a qiskit.circuit.exceptions.CircuitError if not.
Synthesizes the linear function into a quantum circuit.
Parameter validation
Attributes
- 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 instruction label
- Return type
str
- linear¶
Returns the n x n matrix representing this linear function
- name¶
Return the name.
- num_clbits¶
Return the number of clbits.
- num_qubits¶
Return the number of qubits.
- original_circuit¶
Returns the original circuit used to construct this linear function (including None, when the linear function is not constructed from a circuit).
- params¶
return instruction params.
- unit¶
Get the time unit of duration.