# 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 __future__ import annotations
from typing import TYPE_CHECKING, Optional
import cirq
from cirq import ops, value
from qbraid._version import __version__ as qbraid_version
from qbraid.transpiler.annotations import weight
if TYPE_CHECKING:
from qbraid.programs.typer import Qasm2StringType
@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,
) -> Qasm2StringType:
"""Returns a QASM string representing the input Cirq circuit.
Args:
circuit: Cirq circuit to convert to a QASM string.
Returns:
Qasm2StringType: QASM string equivalent to the input Cirq circuit.
"""
circuit = map_zpow_and_unroll(circuit)
return str(_to_qasm_output(circuit, header, precision, qubit_order))