def pswap(phi: float) -> MatrixGate:
"""Returns a Cirq MatrixGate for pyQuil's PSWAP gate.
Args:
phi: Gate parameter (in radians).
Returns:
A MatrixGate equivalent to a PSWAP gate of given angle.
"""
pswap_matrix = np.array([
[1, 0, 0, 0],
[0, 0, np.exp(1j * phi), 0],
[0, np.exp(1j * phi), 0, 0],
[0, 0, 0, 1],
],
dtype=complex)
return MatrixGate(pswap_matrix)
def circuit_from_quil(quil: str) -> Circuit:
"""Convert a Quil program to a Cirq Circuit.
Args:
quil: The Quil program to convert.
Returns:
A Cirq Circuit generated from the Quil program.
Raises:
UnsupportedQuilInstruction: Cirq does not support the specified Quil instruction.
UndefinedQuilGate: Cirq does not support the specified Quil gate.
References:
https://github.com/rigetti/pyquil
"""
circuit = Circuit()
defined_gates = SUPPORTED_GATES.copy()
instructions = parse(quil)
for inst in instructions:
# Add DEFGATE-defined gates to defgates dict using MatrixGate.
if isinstance(inst, DefGate):
if inst.parameters:
raise UnsupportedQuilInstruction(
"Parameterized DEFGATEs are currently unsupported.")
defined_gates[inst.name] = MatrixGate(inst.matrix)
# Pass when encountering a DECLARE.
elif isinstance(inst, Declare):
pass
# Convert pyQuil gates to Cirq operations.
elif isinstance(inst, PyQuilGate):
quil_gate_name = inst.name
quil_gate_params = inst.params
line_qubits = list(LineQubit(q.index) for q in inst.qubits)
if quil_gate_name not in defined_gates:
raise UndefinedQuilGate(
f"Quil gate {quil_gate_name} not supported in Cirq.")
cirq_gate_fn = defined_gates[quil_gate_name]
if quil_gate_params:
circuit += cirq_gate_fn(*quil_gate_params)(*line_qubits)
else:
circuit += cirq_gate_fn(*line_qubits)
# Convert pyQuil MEASURE operations to Cirq MeasurementGate objects.
elif isinstance(inst, PyQuilMeasurement):
line_qubit = LineQubit(inst.qubit.index)
if inst.classical_reg is None:
raise UnsupportedQuilInstruction(
f"Quil measurement {inst} without classical register "
f"not currently supported in Cirq.")
quil_memory_reference = inst.classical_reg.out()
circuit += MeasurementGate(1,
key=quil_memory_reference)(line_qubit)
# Raise a targeted error when encountering a PRAGMA.
elif isinstance(inst, Pragma):
raise UnsupportedQuilInstruction(PRAGMA_ERROR)
# Raise a targeted error when encountering a RESET.
elif isinstance(inst, (Reset, ResetQubit)):
raise UnsupportedQuilInstruction(RESET_ERROR)
# Raise a general error when encountering an unconsidered type.
else:
raise UnsupportedQuilInstruction(
f"Quil instruction {inst} of type {type(inst)} not currently supported in Cirq."
)
return circuit