qcmet.benchmarks.IdleQubitOscillationFrequency

class qcmet.benchmarks.IdleQubitOscillationFrequency(dt, t_max, extra_zz_crosstalk=0, qubit_index=0, crosstalk_qubit_index=None, save_path=None)

Implementation of the idle qubit oscillation frequency metric.

This class generates idle circuits for three initial states, |0>, |+> and |R>, measures the output under three bases, Z, X and Y, and computes the qubit purity oscillation frequency for each initial state, giving the largest among the three as the metric.

__init__(dt, t_max, extra_zz_crosstalk=0, qubit_index=0, crosstalk_qubit_index=None, save_path=None)

Initialize the idle qubit oscillation frequency metric.

Parameters:

• dt (float) – The time interval for each idle step.

• t_max (float) – The max idle time.

• extra_zz_crosstalk (float, optional) – The strength of extra ZZ gates for simulating non-Markovian noise. If non-zero, circuits generated will be two-qubit circuits containing extra ZZ gates for each idle step. Defaults to 0.

• qubit_index (int, optional) – The qubit index for routing. Defaults to 0.

• crosstalk_qubit_index (optional) – The qubit index for the extra qubit used when extra_zz_crosstalk > 0. Defaults to qubit_index + 1.

• save_path (str, optional) – Directory path to save results. Defaults to None.

Methods

__init__(dt, t_max[, extra_zz_crosstalk, ...])	Initialize the idle qubit oscillation frequency metric.
add_idle_gates(circuit, steps)	Add a number of idle gates to circuit corresponding to steps.
analyze()	Analyze measurements to return benchmark results.
change_measurement_basis(circuit, basis)	Change the measurement basis of circuit to be in basis.
fit_func(x, a, b, lambda_, omega)	Exponentially decaying oscillation fit function.
generate_circuits()	Generate benchmark circuits, user facing.
has_plotting()	Check if _plot function is implemented in benchmark.
load_circuit_measurements(circuit_measurements)	Load measurement counts into the experiment_data DataFrame.
measurements_to_probabilities()	Convert raw measurement counts to normalized probabilities.
plot([axes])	Plot benchmark result, user facing.
prepare_initial_state(circuit, initial_state)	Prepare a specified initial state on circuit.
run([device, num_shots, max_circs_per_job])	Run benchmark.
save()	Save benchmark current state.
set_save_path(save_path)	Set benchmark save path if not set in class constructor.

Attributes

circuits	Gets all benchmark circuits.
experiment_data	Getter for experiment_data dataframe.
num_qubits	Number of qubits in this benchmark.

prepare_initial_state(circuit, initial_state)

Prepare a specified initial state on circuit.

Parameters:

• circuit (QuantumCircuit) – An empty circuit.

• initial_state (int) – The initial state, represented by self._Z, self._X or self._Y.

Returns:

None. The method updates circuit in place.

add_idle_gates(circuit, steps)

Add a number of idle gates to circuit corresponding to steps.

Parameters:

• circuit (QuantumCircuit) – A circuit to add idle gates to.

• steps (int) – The number of idle steps.

Returns:

None. The method updates circuit in place.

change_measurement_basis(circuit, basis)

Change the measurement basis of circuit to be in basis.

Parameters:

• circuit (QuantumCircuit) – A circuit to change the measurement basis for.

• basis (int) – The basis to change to, represented by self._Z, self._X or self._Y.

Returns:

None. The method updates circuit in place.

static fit_func(x, a, b, lambda_, omega)

Exponentially decaying oscillation fit function.

This is used for calculating the oscillation frequency of qubit purity.

Parameters:

• x (float or array-like) – Independent variable (number of idle gates).

• a (float) – Readout error fitting parameter.

• b (float) – State preparation error fitting parameter.

• lambda (float) – Decay rate fitting parameter.

• omega (float) – Oscillation frequency fitting parameter.

Returns:

fitting function datapoints.

Return type:

ndarray