Clifford-based randomized benchmarking (RB) of two qubits.

A total of num_circuits random circuits are generated, each of which contains a fixed number of two-qubit Clifford gates plus one additional Clifford that inverts the whole sequence and a measurement in the z-basis. Each circuit is repeated a number of times and the average |00> state population is determined from the measurement outcomes of all of the circuits.

The above process is done for different circuit lengths specified by the integers in num_clifford_range. For example, an integer 10 means the random circuits will contain 10 Clifford gates each plus one inverting Clifford. The user may use the result to extract an average gate fidelity, by analyzing the change in the average |00> state population at different circuit lengths. For actual experiments, one should choose num_clifford_range such that a clear exponential decay is observed in the results.

The two-qubit Cliffords here are decomposed into CZ gates plus single-qubit x and y rotations. See Barends et al., Nature 508, 500 for details.

sampler The quantum engine or simulator to run the circuits.
first_qubit The first qubit under test.
second_qubit The second qubit under test.
num_clifford_range The different numbers of Cliffords in the RB study.
num_circuits The number of random circuits generated for each number of Cliffords.
repetitions The number of repetitions of each circuit.

A RandomizedBenchMarkResult object that stores and plots the result.