# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2021
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""
Circuit synthesis for the Clifford class.
"""
from __future__ import annotations
from qiskit.synthesis.clifford import (
synth_clifford_ag,
synth_clifford_bm,
synth_clifford_greedy,
)
from qiskit.utils.deprecation import deprecate_func
[Doku]@deprecate_func(
additional_msg="Instead, use the function qiskit.synthesis.synth_clifford_full.", since="0.23.0"
)
def decompose_clifford(clifford, method=None):
"""DEPRECATED: Decompose a Clifford operator into a QuantumCircuit.
For N <= 3 qubits this is based on optimal CX cost decomposition
from reference [1]. For N > 3 qubits this is done using the general
non-optimal greedy compilation routine from reference [3],
which typically yields better CX cost compared to the AG method in [2].
Args:
clifford (Clifford): a clifford operator.
method (str): Optional, a synthesis method ('AG' or 'greedy').
If set this overrides optimal decomposition for N <=3 qubits.
Return:
QuantumCircuit: a circuit implementation of the Clifford.
References:
1. S. Bravyi, D. Maslov, *Hadamard-free circuits expose the
structure of the Clifford group*,
`arXiv:2003.09412 [quant-ph] <https://arxiv.org/abs/2003.09412>`_
2. S. Aaronson, D. Gottesman, *Improved Simulation of Stabilizer Circuits*,
Phys. Rev. A 70, 052328 (2004).
`arXiv:quant-ph/0406196 <https://arxiv.org/abs/quant-ph/0406196>`_
3. Sergey Bravyi, Shaohan Hu, Dmitri Maslov, Ruslan Shaydulin,
*Clifford Circuit Optimization with Templates and Symbolic Pauli Gates*,
`arXiv:2105.02291 [quant-ph] <https://arxiv.org/abs/2105.02291>`_
"""
num_qubits = clifford.num_qubits
if method == "AG":
return synth_clifford_ag(clifford)
if method == "greedy":
return synth_clifford_greedy(clifford)
if num_qubits <= 3:
return synth_clifford_bm(clifford)
return synth_clifford_greedy(clifford)