def sample_gate(a: cirq.Qid, b: cirq.Qid,
gate: cirq.FSimGate) -> PhasedFSimCharacterization:
assert isinstance(gate,
cirq.FSimGate), f'Expected FSimGate, got {gate}'
assert np.isclose(gate.theta, np.pi / 4) and np.isclose(
gate.phi, 0.0), f'Expected ISWAP ** -0.5 like gate, got {gate}'
if (a, b) in parameters:
pair_parameters = parameters[(a, b)]
if not isinstance(pair_parameters, PhasedFSimCharacterization):
pair_parameters = PhasedFSimCharacterization(
**pair_parameters)
elif (b, a) in parameters:
pair_parameters = parameters[(b, a)]
if not isinstance(pair_parameters, PhasedFSimCharacterization):
pair_parameters = PhasedFSimCharacterization(
**pair_parameters)
pair_parameters = pair_parameters.parameters_for_qubits_swapped(
)
elif ideal_when_missing_gate:
pair_parameters = SQRT_ISWAP_INV_PARAMETERS
else:
raise ValueError(f'Missing parameters for pair {(a, b)}')
if pair_parameters.any_none():
if not ideal_when_missing_parameter:
raise ValueError(
f'Missing parameter value for pair {(a, b)}, '
f'parameters={pair_parameters}')
pair_parameters = pair_parameters.merge_with(
SQRT_ISWAP_INV_PARAMETERS)
return pair_parameters
def sample_gate(a: cirq.Qid, b: cirq.Qid,
gate: cirq.FSimGate) -> PhasedFSimCharacterization:
_assert_inv_sqrt_iswap_like(gate)
if (a, b) in parameters:
pair_parameters = parameters[(a, b)]
if not isinstance(pair_parameters, PhasedFSimCharacterization):
pair_parameters = PhasedFSimCharacterization(
**pair_parameters)
elif (b, a) in parameters:
pair_parameters = parameters[(b, a)]
if not isinstance(pair_parameters, PhasedFSimCharacterization):
pair_parameters = PhasedFSimCharacterization(
**pair_parameters)
pair_parameters = pair_parameters.parameters_for_qubits_swapped(
)
elif ideal_when_missing_gate:
pair_parameters = SQRT_ISWAP_INV_PARAMETERS
else:
raise ValueError(f'Missing parameters for pair {(a, b)}')
if pair_parameters.any_none():
if not ideal_when_missing_parameter:
raise ValueError(
f'Missing parameter value for pair {(a, b)}, '
f'parameters={pair_parameters}')
pair_parameters = pair_parameters.merge_with(
SQRT_ISWAP_INV_PARAMETERS)
return pair_parameters
def create_with_random_gaussian_sqrt_iswap(
cls,
mean: PhasedFSimCharacterization = SQRT_ISWAP_INV_PARAMETERS,
*,
simulator: Optional[cirq.Simulator] = None,
sigma: PhasedFSimCharacterization = PhasedFSimCharacterization(
theta=0.02, zeta=0.05, chi=0.05, gamma=0.05, phi=0.02),
random_or_seed: cirq.RANDOM_STATE_OR_SEED_LIKE = None,
) -> 'PhasedFSimEngineSimulator':
"""Creates a PhasedFSimEngineSimulator that introduces a random deviation from the mean.
The random deviations are described by a Gaussian distribution of a given mean and sigma,
for each angle respectively.
Each gate for each pair of qubits retains the sampled values for the entire simulation, even
when used multiple times within a circuit.
Attributes:
mean: The mean value for each unitary angle. All parameters must be provided.
simulator: Simulator object to use. When None, a new instance of cirq.Simulator() will
be created.
sigma: The standard deviation for each unitary angle. For sigma parameters that are
None, the mean value will be used without any sampling.
Returns:
New PhasedFSimEngineSimulator instance.
Raises:
ValueError: If not all mean values were supplied.
"""
if mean.any_none():
raise ValueError(
f'All mean values must be provided, got mean of {mean}')
rand = value.parse_random_state(random_or_seed)
def sample_value(gaussian_mean: Optional[float],
gaussian_sigma: Optional[float]) -> float:
assert gaussian_mean is not None
if gaussian_sigma is None:
return gaussian_mean
return rand.normal(gaussian_mean, gaussian_sigma)
def sample_gate(_1: cirq.Qid, _2: cirq.Qid,
gate: cirq.FSimGate) -> PhasedFSimCharacterization:
assert isinstance(gate,
cirq.FSimGate), f'Expected FSimGate, got {gate}'
assert np.isclose(gate.theta, np.pi / 4) and np.isclose(
gate.phi, 0.0), f'Expected ISWAP ** -0.5 like gate, got {gate}'
return PhasedFSimCharacterization(
theta=sample_value(mean.theta, sigma.theta),
zeta=sample_value(mean.zeta, sigma.zeta),
chi=sample_value(mean.chi, sigma.chi),
gamma=sample_value(mean.gamma, sigma.gamma),
phi=sample_value(mean.phi, sigma.phi),
)
if simulator is None:
simulator = cirq.Simulator()
return cls(simulator,
drift_generator=sample_gate,
gates_translator=try_convert_sqrt_iswap_to_fsim)
