CPMG sequence#

In this section we show how to run the dynamical decoupling sequence CPMG.

The CPMG sequence consists in applying N equally spaced $π$ pulses within two $π / 2$ pulses. By increasing the number of $π$ pulses $T_{2}$ should increase since the estimation is less sensitive to noises of the type $1 / f$ eventually reaching the $2 T_{1}$ limit.

The fit is again a dumped exponential of the following form:

p_{e} (t) = A + B e^{- t / T_{2}^{(N)}}

Parameters#

class qibocal.protocols.coherence.cpmg.CpmgParameters(delay_between_pulses_start: int, delay_between_pulses_end: int, delay_between_pulses_step: int, single_shot: bool = False, n: int = 1)[source]

Cpmg runcard inputs.

n: int = 1: Number of pi rotations.

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

single_shot: bool = False

delay_between_pulses_start: int: Initial delay between pulses [ns].

delay_between_pulses_end: int: Final delay between pulses [ns].

delay_between_pulses_step: int: Step delay between pulses [ns].

nshots: int: Number of executions on hardware.

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

Example#

A possible runcard to launch a CPMG experiment could be the following:

- id: CPMG
  operation: cpmg
  parameters:
    delay_between_pulses_end: 100000
    delay_between_pulses_start: 4
    delay_between_pulses_step: 1000
    n: 10
    nshots: 1000

The expected output is the following:

$T_{2}$ is determined by fitting the output signal using the formula presented above.

Requirements#

Single Shot Experiments