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Simulator

List of simulation methods in the Simulator

method name	parameters	output
prob_amplitude	input_state: BasicState or StateVector, output_state: BasicState	prob. amplitude (complex)
probability	input_state: BasicState or StateVector, output_state: BasicState	probability (float [0;1])
probs	input_state: BasicState or StateVector	prob. distribution (BSD)
probs_svd	input_dist: SVDistribution	Python dictionary
evolve	input_state: BasicState or StateVector	evolved StateVector

class perceval.simulators.Simulator(backend)

A simulator class relying on a probability amplitude capable backend to simulate the output of a unitary non-polarized circuit given an BasicState, StateVector or SVDistribution input. The simulator is able to evolve or simulate the sampling a states with annotated photons.

Parameters:

backend (AStrongSimulationBackend) – A probability amplitude capable backend object

clear_postselection()

Clear the post-selection function

evolve(input_state)

Evolve a state through the circuit

Parameters:

input_state (BasicState | StateVector) – The input fock state or state vector

Return type:

StateVector

Returns:

The output state vector

evolve_density_matrix(dm)

Compute the DensityMatrix evolved from “dm” through a Linear optical circuit

Parameters:

dm (DensityMatrix) – The density Matrix to evolve

Return type:

DensityMatrix

Returns:

The evolved DensityMatrix

evolve_svd(svd, progress_callback=None)

Compute the SVDistribution evolved through a Linear Optical circuit

Parameters:

• svd (SVDistribution | StateVector | BasicState) – The input StateVector distribution

• progress_callback (Callable) – A function with the signature func(progress: float, message: str)

Return type:

dict

Returns:

A dictionary of the form { “results”: SVDistribution, “physical_perf”: float, “logical_perf”: float }

• results is the post-selected output SVDistribution

• physical_perf is the performance computed from the detected photon filter

• logical_perf is the performance computed from the post-selection

keep_heralds(value)

Tells the simulator to keep or discard ancillary modes in output states

Parameters:

value (bool) – True to keep ancillaries/heralded modes, False to discard them (default is keep).

log_resources(method, extra_parameters)

Log resources of the simulator

Parameters:

• method (str) – name of the method used

• extra_parameters (dict) –

  extra parameters to log

  Extra parameter can be:

  • n

probs_density_matrix(dm)

gives the output probability distribution, after evolving some density matrix through the simulator :type dm: DensityMatrix :param dm: the input DensityMatrix

Return type:

dict

probs_svd(input_dist, detectors=None, progress_callback=None)

Compute the probability distribution from a SVDistribution input and as well as performance scores

Parameters:

• input_dist (SVDistribution) – A state vector distribution describing the input to simulate

• detectors (Optional[list[IDetector]]) – An optional list of detectors

• progress_callback (Optional[Callable]) – A function with the signature func(progress: float, message: str)

Return type:

dict[str, any]

Returns:

A dictionary of the form { “results”: BSDistribution, “physical_perf”: float, “logical_perf”: float }

• results is the post-selected output state distribution

• physical_perf is the performance computed from the detected photon filter

• logical_perf is the performance computed from the post-selection

set_circuit(circuit)

Set a circuit for simulation.

Parameters:

circuit (ACircuit) – a unitary circuit without polarized components

set_min_detected_photon_filter(value)

Set a minimum number of detected photons in the output distribution

Parameters:

value (int) – The minimum photon count

set_min_detected_photons_filter(value)

Set a minimum number of detected photons in the output distribution

Parameters:

value (int) – The minimum photon count

set_postselection(postselect)

Set a post-selection function

Parameters:

postselect (PostSelect) – a PostSelect object

set_selection(min_detected_photons_filter=None, postselect=None, heralds=None, min_detected_photon_filter=None)

Set multiple selection filters at once to remove unwanted states from computed output distribution

Parameters:

• min_detected_photons_filter (Optional[int]) – minimum number of detected photons in the output distribution

• postselect (Optional[PostSelect]) – a post-selection function

• heralds (Optional[dict]) – expected detections (heralds). Only corresponding states will be selected, others are filtered out. Mapping of heralds. For instance {5: 0, 6: 1} means 0 photon is expected on mode 5 and 1 on mode 6.