BaseFermionBackend.measure_observable_expectation

BaseFermionBackend.measure_observable_expectation(circuits, observable, shots, seed=None, num_species=1, get_variance=False)

Measure the expectation value of an observable in a state prepared by a given quantum circuit that uses fermionic gates. Measurements are added to the entire register if they are not yet applied in the circuit.

Parameters:

• circuits (Union[QuantumCircuit, List[QuantumCircuit]]) – QuantumCircuit applying gates with fermionic generators

• observable (FermionicOp) – A FermionicOp describing an observable of which the expectation value is sampled

• shots (int) – Number of measurement shots taken in case the circuit has measure instructions

• seed (Optional[int]) – seed for the random number generator of the measurement simulation

• num_species (int) – number of different fermionic species described by the circuits

• get_variance (bool) – If True, also returns an estimate of the variance of the observable

Raises:

QiskitColdAtomError – if the observable is non-diagonal

Returns:

List of the measured expectation values of the observables in given circuits variance: List of the estimated variances of of the observables (if get_variance is True)

Return type:

observable_ev