Randomized Benchmarking

RandomizedBenchmarkingModel - Likelihood for RB experiments

Class Reference

class qinfer.RandomizedBenchmarkingModel(interleaved=False, order=0)

Bases: qinfer.abstract_model.FiniteOutcomeModel, qinfer.abstract_model.DifferentiableModel

Implements the randomized benchmarking or interleaved randomized benchmarking protocol, such that the depolarizing strength $p$ of the twirled channel is a parameter to be estimated, given a sequnce length $m$ as an experimental control. In addition, the zeroth-order “fitting”-parameters $A$ and $B$ are represented as model parameters to be estimated.

Parameters:

interleaved (bool) – If True, the model implements the interleaved protocol, with $\tilde{p}$ being the depolarizing parameter for the interleaved gate and with $p_{\text{ref}}$ being the reference parameter.

Model Parameters:  

• p – Fidelity of the twirled error channel $\Lambda$, represented as a decay rate $p = (d F - 1) / (d - 1)$, where $F$ is the fidelity and $d$ is the dimension of the Hilbert space.
• A – Scale of the randomized benchmarking decay, defined as $\Tr[Q \Lambda(\rho - \ident / d)]$, where $Q$ is the final measurement, and where $\ident$ is the initial preparation.
• B – Offset of the randomized benchmarking decay, defined as $\Tr[Q \Lambda(\ident / d)]$.

Experiment Parameters:  

• m (int) – Length of the randomized benchmarking sequence that was measured.

n_modelparams

modelparam_names

is_n_outcomes_constant

expparams_dtype

n_outcomes(expparams)

are_models_valid(modelparams)

likelihood(outcomes, modelparams, expparams)

score(outcomes, modelparams, expparams, return_L=False)

Function Reference

qinfer.rb.p(F, d=2)

Given the fidelity of a gate in $d$ dimensions, returns the depolarizating probability of the twirled channel.

Parameters:

• F (float) – Fidelity of a gate.
• d (int) – Dimensionality of the Hilbert space on which the gate acts.

qinfer.rb.F(p, d=2)

Given the depolarizating probabilty of a twirled channel in $d$ dimensions, returns the fidelity of the original gate.

Parameters:

• p (float) – Depolarizing parameter for the twirled channel.
• d (int) – Dimensionality of the Hilbert space on which the gate acts.