EstimatorFromSampler

Module: iqm.qaoa.backends

class iqm.qaoa.backends.EstimatorFromSampler(sampler, shots, cvar=None)

Bases: EstimatorBackend

The estimator class for calculating the expectation value using counts obtained from a sampler.

Takes an instance of a subclass of SamplerBackend and uses it to generate samples from the QAOA. These energy of these samples is then calculated classically and averaged-out to produce an estimate of the expectation value of the Hamiltonian. If cvar is provided, the estimator returns not the average of the energies, but its CVaR at the cvar threshold.

Parameters:

• sampler (SamplerBackend) – The sampler to produce the samples.

• shots (int) – The number of shots that should be produced with the sampler.

• cvar (float | None) – The threshold used to calculate CVaR (if provided).

Raises:

ValueError – If cvar is provided, but it’s not between 0 (excluded) and 1 (included).

Methods

Inheritance