qrunch.quantum.measurement_caches.minimal_measurement_cache

Module containing a minimal measurement cache.

Classes

MinimalMeasurementCache

Minimal measurement cache used for samplers and estimators.
class MinimalMeasurementCache

Bases: MeasurementCache

Minimal measurement cache used for samplers and estimators.

This cache saves measurements taken on a circuit and full expectation values measured on circuits. The measurements are not used to calculate expectation values, i.e., if the exact operator has not been measured before it will not be cached.

__init__(cached_measurement_limit: int = 10000, cached_expectation_value_limit: int = 100) → None

Initiate an instance of a minimal cache.

Parameters:

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

  • cached_expectation_value_limit (int) – Maximum number of cached expectation values. Defaults to 100.

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