Rabi experiments#

In this section we present all Rabi experiments provided by Qibocal.

Rabi lenght and amplitude#

The goal of the Rabi experiment is to tune the amplitude (duration) of the drive pulse, in order to excite the qubit from the ground state up to state \(\ket{1}\).

In the Rabi experiment, the qubit is probed with a drive pulse at the qubit frequency \(w_{01}\) before measuring. This pulse sequence is repeated multiple times changing the amplitude (duration) of the pulse. The qubit starts in the ground state, changing one of the two parameters of the drive pulse, the probability of being in the first excited state increases following a sinusoidal pattern.

For the amplitude version, we expect:

\[p_e(t) =\frac{1}{2} \left( 1 - \cos\left(\Omega_R t \right) \right)\]

For the time version, we have to take into account the dephasing and the energy decay. In case the Rabi rate is larger than the decay and the pure dephasing rate,

\[p_e(t) = \frac{1}{2} \left(1- e^{-t/\tau} \cos\left(\Omega_R \frac{t}{2}\right)\right)\]

where \(\Omega_R\) is the Rabi frequency and \(\tau\) the decay time.

Parameters#

class qibocal.protocols.rabi.amplitude.RabiAmplitudeParameters(min_amp_factor: float, max_amp_factor: float, step_amp_factor: float, pulse_length: Optional[float] = None)[source]

RabiAmplitude runcard inputs.

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

pulse_length: Optional[float] = None: RX pulse duration [ns].

min_amp_factor: float: Minimum amplitude multiplicative factor.

max_amp_factor: float: Maximum amplitude multiplicative factor.

step_amp_factor: float: Step amplitude multiplicative factor.

nshots: int: Number of executions on hardware.

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

class qibocal.protocols.rabi.length.RabiLengthParameters(pulse_duration_start: float, pulse_duration_end: float, pulse_duration_step: float, pulse_amplitude: Optional[float] = None)[source]

RabiLength runcard inputs.

pulse_duration_start: float: Initial pi pulse duration [ns].

pulse_duration_end: float: Final pi pulse duration [ns].

pulse_duration_step: float: Step pi pulse duration [ns].

pulse_amplitude: Optional[float] = None: Pi pulse amplitude. Same for all qubits.

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 an example of the experiment parameters.

- id: Rabi amplitude
  operation: rabi_amplitude
  parameters:
    min_amp_factor: 0.1
    max_amp_factor: 1.
    step_amp_factor: 0.01
    pulse_length: 40
    nshots: 3000
    relaxation_time: 50000

To run properly this experiment it is important to set the relaxation_time higher than the qubit T1.

After running qq auto, the experiment is executed and the result will looks like the following picture.

Regarding the time version of this experiment, this is an example

- id: Rabi length
  operation: rabi_length
  parameters:
    pulse_duration_start: 16
    pulse_duration_end: 100
    pulse_duration_step: 4
    pulse_amplitude: 0.22
    nshots: 3000
    relaxation_time: 50000

For each Rabi experiment Qibocal provides the signal version, where just the readout signal is acquired, without performing state discrimination qibocal.protocols.rabi.amplitude_signal.rabi_amplitude_signal, qibocal.protocols.rabi.length_signal.rabi_length_signal.

It follows an example runcard and plot for the signal exepriment

- id: Rabi signal
  operation: rabi_amplitude_signal
  parameters:
    min_amp_factor: 0.2
    max_amp_factor: 1.
    step_amp_factor: 0.01
    pulse_length: 40
    nshots: 3000
    relaxation_time: 50000

Requirements#

Rabi ef#

This experiment is used to characterized the \(\pi_{12}\) pulse, in order to change the qubit state from \(\ket{1}\) to \(\ket{2}\). The experiment is similar to the Rabi experiment, but at the beginning the state should be prepared in the \(\ket{1}\) state through a \(\pi_{01}\) pulse.

Example#

It follows an example of runcard and a generated report.

- id: Rabi ef
  operation: rabi_amplitude_ef
  parameters:
    min_amp_factor: 0.2
    max_amp_factor: 1.
    step_amp_factor: 0.01
    pulse_length: 400
    nshots: 3000
    relaxation_time: 50000

Requirements#

Rabi experiments