Samplers

Sampler	A sampler for measurements of quantum circuits.
HomodyneSampler	A sampler for homodyne measurements.
PNRSampler	A sampler for photon-number resolving (PNR) detectors.

Sampler

class mrmustard.lab.samplers.Sampler(meas_outcomes, povms=None)

A sampler for measurements of quantum circuits.

Parameters:

• meas_outcomes (Sequence[Any]) – The measurement outcomes for this sampler.

• povms (CircuitComponent | Sequence[CircuitComponent] | None) – The (optional) POVMs of this sampler.

property povms: CircuitComponent | Sequence[CircuitComponent] | None

The POVMs of this sampler.

property meas_outcomes: Sequence[Any]

The measurement outcomes of this sampler.

abstract probabilities(state, atol=0.0001)

Returns the probability distribution of a state w.r.t. measurement outcomes.

Parameters:

• state (State) – The state to generate the probability distribution of. Note: the input state must be normalized.

• atol (float) – The absolute tolerance used for validating that the computed probability distribution sums to 1.

Return type:

Sequence[float]

sample(state, n_samples=1000, seed=None)

Returns an array of samples given a state.

Parameters:

• state (State) – The state to sample.

• n_samples (int) – The number of samples to generate.

• seed (int | None) – An optional seed for random sampling.

Returns:

An array of samples such that the shape is (n_samples, n_modes).

Return type:

ndarray

sample_prob_dist(state, n_samples=1000, seed=None)

Samples a state by computing the probability distribution.

Parameters:

• state (State) – The state to sample.

• n_samples (int) – The number of samples to generate.

• seed (int | None) – An optional seed for random sampling.

Returns:

A tuple of the generated samples and the probability of obtaining the sample.

Return type:

tuple[ndarray, ndarray]

HomodyneSampler

class mrmustard.lab.samplers.HomodyneSampler(phi=0, bounds=(-10, 10), num=1000)

Bases: Sampler

A sampler for homodyne measurements.

Parameters:

• phi (float) – The quadrature angle where 0 corresponds to x and \pi/2 to p.

• bounds (tuple[float, float]) – The range of values to discretize over.

• num (int) – The number of points to discretize over.

probabilities(state, atol=0.0001)

Returns the probability distribution of a state w.r.t. measurement outcomes.

Parameters:

• state – The state to generate the probability distribution of. Note: the input state must be normalized.

• atol – The absolute tolerance used for validating that the computed probability distribution sums to 1.

sample(state, n_samples=1000, seed=None)

Returns an array of samples given a state.

Parameters:

• state (State) – The state to sample.

• n_samples (int) – The number of samples to generate.

• seed (int | None) – An optional seed for random sampling.

Returns:

An array of samples such that the shape is (n_samples, n_modes).

Return type:

ndarray

PNRSampler

class mrmustard.lab.samplers.PNRSampler(cutoff)

Bases: Sampler

A sampler for photon-number resolving (PNR) detectors.

Parameters:

cutoff (int) – The photon number cutoff.

probabilities(state, atol=0.0001)

Returns the probability distribution of a state w.r.t. measurement outcomes.

Parameters:

• state – The state to generate the probability distribution of. Note: the input state must be normalized.

• atol – The absolute tolerance used for validating that the computed probability distribution sums to 1.

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