qrunch.quantum.measurement_caches.full_measurement_cache

Module containing a full measurement cache.

Classes

FullMeasurementCache

Full measurement cache used for samplers and estimators.
class FullMeasurementCache

Bases: MeasurementCache

Full measurement cache used for samplers and estimators.

This cache saves measurements taken on a circuit. Expectation values are cached indirectly through the measurements. Thus the cache can combine many measurement into calculating one partial expectation value, maximally exploiting previous measurements.

__init__(cached_measurement_limit: int = 10000) → None

Initiate an instance of a minimal cache.

Parameters:

cached_measurement_limit (int) – Maximum number of cached measurements. Defaults to 10000.

Return type:

None

clear() → None

Clear the cache.

Return type:

None

load_expectation_value_from_cache(circuit: Circuit, observable: HermitianPauliSum, shots: int | None) → tuple[HermitianPauliSum, ExpectationValue]

Load an expectation value from the cache.

For the minimal cache, either the observable is either fully returned as a hermitian pauli sum or as an expectation value.

Parameters:

  • circuit (Circuit) – Circuit on which the measurement was performed.

  • observable (HermitianPauliSum) – Observable for which the expectation value is needed.

  • shots (int | None) – Number of shots.

Return type:

tuple[HermitianPauliSum, ExpectationValue]

load_measurement_from_cache(measurement_circuit: MeasurementCircuit, shots: int | None) → QuantumMeasurement | None

Load a measurement from cache.

Parameters:

  • measurement_circuit (MeasurementCircuit) – Circuit on which the measurement was performed.

  • shots (int | None) – Number of shots in the needed measurement.

Return type:

QuantumMeasurement | None

save_expectation_value_to_cache(circuit: Circuit, observable: HermitianPauliSum, shots: int | None, expectation_value: ExpectationValue) → None

Save expectation value to cache.

This included the expectation value and/or the measurement used to obtain the expectation value.

Parameters:

  • circuit (Circuit) – Circuit on which the measurement was performed.

  • observable (HermitianPauliSum) – Observable which has been measured.

  • shots (int | None) – Number of shots.

  • expectation_value (ExpectationValue) – Expectation value of the observable.

Return type:

None

save_measurement_to_cache(measurement_circuit: MeasurementCircuit, measurement: QuantumMeasurement) → None

Save a measurement to the cache.

Parameters:
Return type:

None