Flipping#

The flipping experiment corrects the amplitude in the qubit drive pulse for \(R_x(\pi)\) rotations. In this experiment, we apply an \(R_x(\pi/2)\) rotation followed by \(N\) flips (two \(R_x(\pi)\) rotations) and we measure the qubit state. The first \(R_x(\pi/2)\) is necessary to discriminate the over rotations and under rotations of the \(R_x(\pi)\) pulse: without it the difference between the two cases is just a global phase, i.e., the probabilities are the same. With the \(R_x(\pi/2)\) pulse, in case of under rotations the state will be closer to \(\ket{0}\) after the initial flip, in the over rotations one the final state will be closer to \(\ket{1}\).

By fitting the resulting data with a sinusoidal function, we can determine the delta amplitude, which allows us to refine the \(\pi\) pulse amplitude.

We implemented also a version of the flipping protocol to calibrate the drive pulse amplitude of the \(R_x(\pi/2)\) rotations, in this case each \(R_x(\pi)\) rotation is replaced by two \(R_x(\pi/2)\) rotations. The main reasons for implementing protocols to fine tune the R_x(pi/2) rotations are explained in Rabi experiments.

Parameters#

class qibocal.protocols.flipping.FlippingParameters(nflips_max: int, nflips_step: int, unrolling: bool = False, delta_amplitude: float = 0, rx90: bool = False)[source]

Flipping runcard inputs.

nflips_max: int: Maximum number of flips ([RX(pi) - RX(pi)] sequences).

nflips_step: int: Flip step.

unrolling: bool = False: If True it uses sequence unrolling to deploy multiple sequences in a single instrument call. Defaults to False.

delta_amplitude: float = 0: Amplitude detuning.

rx90: bool = False: Calibration of native pi pulse, if true calibrates pi/2 pulse

hardware_average: bool = False: By default hardware average will be performed.

nshots: int: Number of executions on hardware.

relaxation_time: float: Wait time for the qubit to decohere back to the gnd state.

Example#

It follows a runcard example of this experiment.

- id: flipping
  operation: flipping
  parameters:
    delta_amplitude: 0.05
    nflips_max: 30
    nflips_step: 1

The expected output is the following:

If the same experiment is run setting the rx90: True the flipping is performed to calibrate the amplitude of the \(R_x(\pi/2)\) rotation

- id: flipping
  operation: flipping
  parameters:
    delta_amplitude: 0.05
    nflips_max: 30
    nflips_step: 1
    rx90: True

Flipping#

Parameters#

Example#

Requirements#