def try_convert_sqrt_iswap_to_fsim(gate: Gate) -> Optional[FSimGate]:
"""Converts an equivalent gate to FSimGate(theta=π/4, phi=0) if possible.
Args:
gate: Gate to verify.
Returns:
FSimGate(theta=π/4, phi=0) if provided gate either FSimGate, ISWapPowGate, PhasedFSimGate
or PhasedISwapPowGate that is equivalent to FSimGate(theta=π/4, phi=0). None otherwise.
"""
if isinstance(gate, FSimGate):
if not np.isclose(gate.phi, 0.0):
return None
angle = gate.theta
elif isinstance(gate, ISwapPowGate):
angle = -gate.exponent * np.pi / 2
elif isinstance(gate, PhasedFSimGate):
if (not np.isclose(gate.zeta, 0.0) or not np.isclose(gate.chi, 0.0)
or not np.isclose(gate.gamma, 0.0)
or not np.isclose(gate.phi, 0.0)):
return None
angle = gate.theta
elif isinstance(gate, PhasedISwapPowGate):
if not np.isclose(-gate.phase_exponent - 0.5, 0.0):
return None
angle = gate.exponent * np.pi / 2
else:
return None
if np.isclose(angle, np.pi / 4):
return FSimGate(theta=np.pi / 4, phi=0.0)
return None
def try_convert_sqrt_iswap_to_fsim(gate: Gate) -> Optional[PhaseCalibratedFSimGate]:
"""Converts an equivalent gate to FSimGate(theta=π/4, phi=0) if possible.
Args:
gate: Gate to verify.
Returns:
FSimGateCalibration with engine_gate FSimGate(theta=π/4, phi=0) if the provided gate is
either FSimGate, ISWapPowGate, PhasedFSimGate or PhasedISwapPowGate that is equivalent to
FSimGate(theta=±π/4, phi=0). None otherwise.
"""
if isinstance(gate, FSimGate):
if not np.isclose(gate.phi, 0.0):
return None
angle = gate.theta
elif isinstance(gate, ISwapPowGate):
angle = -gate.exponent * np.pi / 2
elif isinstance(gate, PhasedFSimGate):
if (
not np.isclose(gate.zeta, 0.0)
or not np.isclose(gate.chi, 0.0)
or not np.isclose(gate.gamma, 0.0)
or not np.isclose(gate.phi, 0.0)
):
return None
angle = gate.theta
elif isinstance(gate, PhasedISwapPowGate):
if not np.isclose(-gate.phase_exponent - 0.5, 0.0):
return None
angle = gate.exponent * np.pi / 2
else:
return None
angle_canonical = angle % (2 * np.pi)
if np.isclose(angle_canonical, np.pi / 4):
return PhaseCalibratedFSimGate(FSimGate(theta=np.pi / 4, phi=0.0), 0.0)
elif np.isclose(angle_canonical, 7 * np.pi / 4):
return PhaseCalibratedFSimGate(FSimGate(theta=np.pi / 4, phi=0.0), 0.5)
return None
def from_characterization(
cls,
qubits: Tuple[Qid, Qid],
gate: FSimGate,
parameters: PhasedFSimCharacterization,
characterization_index: Optional[int],
) -> 'FSimPhaseCorrections':
"""Creates an operation that compensates for zeta, chi and gamma angles of the supplied
gate and characterization.
Args:
qubits: Qubits that the gate should act on.
gate: Original, imperfect gate that is supposed to run on the hardware.
parameters: The real parameters of the supplied gate.
characterization_index: characterization index to use at each moment with gate.
"""
assert parameters.zeta is not None, "Zeta value must not be None"
zeta = parameters.zeta
assert parameters.gamma is not None, "Gamma value must not be None"
gamma = parameters.gamma
assert parameters.chi is not None, "Chi value must not be None"
chi = parameters.chi
a, b = qubits
alpha = 0.5 * (zeta + chi)
beta = 0.5 * (zeta - chi)
operations = (
(rz(0.5 * gamma - alpha).on(a), rz(0.5 * gamma + alpha).on(b)),
(gate.on(a, b),),
(rz(0.5 * gamma - beta).on(a), rz(0.5 * gamma + beta).on(b)),
)
moment_to_calibration = [None, characterization_index, None]
return cls(operations, moment_to_calibration)