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Replace standard deviation in operator estimation with standard error #870

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merged 4 commits into from
Apr 19, 2019
Merged

Replace standard deviation in operator estimation with standard error #870

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1b98fd4
Replacing stddev with std_err
Apr 2, 2019
df7195d
Re-arranging wording of optional argument
Apr 2, 2019
13addf9
Tests for changing optional argument name
Apr 2, 2019
e6f7ac7
Using f-strings
Apr 3, 2019
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40 changes: 20 additions & 20 deletions pyquil/operator_estimation.py
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Original file line number Diff line number Diff line change
Expand Up @@ -719,16 +719,16 @@ class ExperimentResult:

setting: ExperimentSetting
expectation: Union[float, complex]
stddev: Union[float, complex]
std_err: Union[float, complex]
total_counts: int
raw_expectation: Union[float, complex] = None
raw_stddev: float = None
raw_std_err: float = None
calibration_expectation: Union[float, complex] = None
calibration_stddev: Union[float, complex] = None
calibration_std_err: Union[float, complex] = None
calibration_counts: int = None

def __str__(self):
return f'{self.setting}: {self.expectation} +- {self.stddev}'
return f'{self.setting}: {self.expectation} +- {self.std_err}'

def __repr__(self):
return f'ExperimentResult[{self}]'
Expand All @@ -738,19 +738,19 @@ def serializable(self):
'type': 'ExperimentResult',
'setting': self.setting,
'expectation': self.expectation,
'stddev': self.stddev,
'std_err': self.std_err,
'total_counts': self.total_counts,
'raw_expectation': self.raw_expectation,
'raw_stddev': self.raw_stddev,
'raw_std_err': self.raw_std_err,
'calibration_expectation': self.calibration_expectation,
'calibration_stddev': self.calibration_stddev,
'calibration_std_err': self.calibration_std_err,
'calibration_counts': self.calibration_counts,
}


def measure_observables(qc: QuantumComputer, tomo_experiment: TomographyExperiment,
n_shots: int = 10000, progress_callback=None, active_reset=False,
readout_symmetrize: str = 'exhaustive',
symmetrize_readout: str = 'exhaustive',
calibrate_readout: str = 'plus-eig'):
"""
Measure all the observables in a TomographyExperiment.
Expand All @@ -766,7 +766,7 @@ def measure_observables(qc: QuantumComputer, tomo_experiment: TomographyExperime
to True is much faster but there is a ~1% error per qubit in the reset operation.
Thermal noise from "traditional" reset is not routinely characterized but is of the same
order.
:param readout_symmetrize: Method used to symmetrize the readout errors, i.e. set
:param symmetrize_readout: Method used to symmetrize the readout errors, i.e. set
p(0|1) = p(1|0). For uncorrelated readout errors, this can be achieved by randomly
selecting between the POVMs {X.D1.X, X.D0.X} and {D0, D1} (where both D0 and D1 are
diagonal). However, here we currently support exhaustive symmetrization and loop through
Expand All @@ -781,7 +781,7 @@ def measure_observables(qc: QuantumComputer, tomo_experiment: TomographyExperime
The preceding symmetrization and this step together yield a more accurate estimation of the observable. Set to `None` if no calibration is desired.
"""
# calibration readout only works with symmetrization turned on
if calibrate_readout is not None and readout_symmetrize is None:
if calibrate_readout is not None and symmetrize_readout is None:
raise ValueError("Readout calibration only works with readout symmetrization turned on")

# Outer loop over a collection of grouped settings for which we can simultaneously
Expand Down Expand Up @@ -809,10 +809,10 @@ def measure_observables(qc: QuantumComputer, tomo_experiment: TomographyExperime
# 2. Symmetrization
qubits = max_weight_out_op.get_qubits()

if readout_symmetrize == 'exhaustive' and len(qubits) > 0:
if symmetrize_readout == 'exhaustive' and len(qubits) > 0:
bitstrings, d_qub_idx = _exhaustive_symmetrization(qc, qubits, n_shots, total_prog)

elif readout_symmetrize is None and len(qubits) > 0:
elif symmetrize_readout is None and len(qubits) > 0:
total_prog_no_symm = total_prog.copy()
ro = total_prog_no_symm.declare('ro', 'BIT', len(qubits))
d_qub_idx = {}
Expand Down Expand Up @@ -853,7 +853,7 @@ def measure_observables(qc: QuantumComputer, tomo_experiment: TomographyExperime
yield ExperimentResult(
setting=setting,
expectation=coeff,
stddev=0.0,
std_err=0.0,
total_counts=n_shots,
)
continue
Expand All @@ -866,7 +866,7 @@ def measure_observables(qc: QuantumComputer, tomo_experiment: TomographyExperime
# 4.1 Obtain calibration program
calibr_prog = _calibration_program(qc, tomo_experiment, setting)
# 4.2 Perform symmetrization on the calibration program
if readout_symmetrize == 'exhaustive':
if symmetrize_readout == 'exhaustive':
qubs_calibr = setting.out_operator.get_qubits()
calibr_shots = n_shots
calibr_results, d_calibr_qub_idx = _exhaustive_symmetrization(qc, qubs_calibr, calibr_shots, calibr_prog)
Expand All @@ -883,12 +883,12 @@ def measure_observables(qc: QuantumComputer, tomo_experiment: TomographyExperime
yield ExperimentResult(
setting=setting,
expectation=corrected_mean.item(),
stddev=np.sqrt(corrected_var).item(),
std_err=np.sqrt(corrected_var).item(),
total_counts=n_shots,
raw_expectation=obs_mean.item(),
raw_stddev=np.sqrt(obs_var).item(),
raw_std_err=np.sqrt(obs_var).item(),
calibration_expectation=obs_calibr_mean.item(),
calibration_stddev=np.sqrt(obs_calibr_var).item(),
calibration_std_err=np.sqrt(obs_calibr_var).item(),
calibration_counts=calibr_shots,
)

Expand All @@ -897,7 +897,7 @@ def measure_observables(qc: QuantumComputer, tomo_experiment: TomographyExperime
yield ExperimentResult(
setting=setting,
expectation=obs_mean.item(),
stddev=np.sqrt(obs_var).item(),
std_err=np.sqrt(obs_var).item(),
total_counts=n_shots,
)

Expand Down Expand Up @@ -1000,7 +1000,7 @@ def _exhaustive_symmetrization(qc: QuantumComputer, qubits: List[int],
# Symmetrize -- flip qubits pre-measurement
n_shots_symm = int(round(np.ceil(shots / 2**len(qubits))))
if n_shots_symm * 2**len(qubits) > shots:
warnings.warn("Symmetrization increasing number of shots from {} to {}".format(shots, round(n_shots_symm * 2**len(qubits))))
warnings.warn(f"Symmetrization increasing number of shots from {shots} to {round(n_shots_symm * 2**len(qubits))}")
list_bitstrings_symm = []
for ops_bool in itertools.product([0, 1], repeat=len(qubits)):
total_prog_symm = prog.copy()
Expand Down Expand Up @@ -1034,7 +1034,7 @@ def _calibration_program(qc: QuantumComputer, tomo_experiment: TomographyExperim

:param tomo_experiment: A suite of tomographic observables
:param ExperimentSetting: The particular tomographic observable to measure
:param readout_symmetrize: Method used to symmetrize the readout errors (see docstring for
:param symmetrize_readout: Method used to symmetrize the readout errors (see docstring for
`measure_observables` for more details)
:param cablir_shots: number of shots to take in the measurement process
:return: Program performing the calibration
Expand Down
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