# Copyright (C) 2024 qBraid
#
# This file is part of the qBraid-SDK
#
# The qBraid-SDK is free software released under the GNU General Public License v3
# or later. You can redistribute and/or modify it under the terms of the GPL v3.
# See the LICENSE file in the project root or <https://www.gnu.org/licenses/gpl-3.0.html>.
#
# THERE IS NO WARRANTY for the qBraid-SDK, as per Section 15 of the GPL v3.
"""
Module for conversions between Cirq Circuits and QASM strings
"""
from typing import Optional
import cirq
from cirq import ops, value
from qbraid._version import __version__ as qbraid_version
from qbraid.transpiler.annotations import weight
@value.value_equality
class ZPowGate(cirq.ZPowGate):
"""A single qubit gate for rotations around the
Z axis of the Bloch sphere.
"""
def _qasm_(self, args: "cirq.QasmArgs", qubits: tuple["cirq.Qid", ...]) -> Optional[str]:
args.validate_version("2.0")
if self._global_shift == 0:
if self._exponent == 0.25:
return args.format("t {0};\n", qubits[0])
if self._exponent == -0.25:
return args.format("tdg {0};\n", qubits[0])
if self._exponent == 0.5:
return args.format("s {0};\n", qubits[0])
if self._exponent == -0.5:
return args.format("sdg {0};\n", qubits[0])
if self._exponent == 1:
return args.format("z {0};\n", qubits[0])
return args.format("p({0:half_turns}) {1};\n", self._exponent, qubits[0])
return args.format("rz({0:half_turns}) {1};\n", self._exponent, qubits[0])
def map_zpow_and_unroll(circuit: cirq.Circuit) -> cirq.Circuit:
"""Map ZPowGate to RZ and unroll circuit"""
def _map_zpow(op: cirq.Operation, _: int) -> cirq.OP_TREE:
if isinstance(op.gate, cirq.ZPowGate):
yield ZPowGate(exponent=op.gate.exponent, global_shift=op.gate.global_shift)(
op.qubits[0]
)
else:
yield op
return cirq.map_operations_and_unroll(circuit, _map_zpow)
def _to_qasm_output(
circuit: cirq.Circuit,
header: Optional[str] = None,
precision: int = 10,
qubit_order: "cirq.QubitOrderOrList" = ops.QubitOrder.DEFAULT,
) -> "cirq.QasmOutput":
"""Returns a QASM object equivalent to the circuit.
Args:
header: A multi-line string that is placed in a comment at the top
of the QASM. Defaults to a cirq version specifier.
precision: Number of digits to use when representing numbers.
qubit_order: Determines how qubits are ordered in the QASM
register.
"""
if header is None:
header = f"Generated from qBraid v{qbraid_version}"
qubits = ops.QubitOrder.as_qubit_order(qubit_order).order_for(circuit.all_qubits())
return cirq.QasmOutput(
operations=circuit.all_operations(),
qubits=qubits,
header=header,
precision=precision,
version="2.0",
)
[docs]
@weight(1)
def cirq_to_qasm2(
circuit: cirq.Circuit,
header: Optional[str] = None,
precision: int = 10,
qubit_order: "cirq.QubitOrderOrList" = ops.QubitOrder.DEFAULT,
) -> str:
"""Returns a QASM string representing the input Cirq circuit.
Args:
circuit: Cirq circuit to convert to a QASM string.
Returns:
QASMType: QASM string equivalent to the input Cirq circuit.
"""
circuit = map_zpow_and_unroll(circuit)
return str(_to_qasm_output(circuit, header, precision, qubit_order))