Flux crosstalk experiments#
In this section we show how to run flux crosstalk experiments.
As we saw in Flux tunable qubits the external flux affecting a qubit line \(i\) will receive contributions from other qubits
which means that the transmon frequency can change when current is applied on other qubits.
Qubit crosstalk#
It is possible to measure qubit crosstalk by running a qubit_crosstalk experiment. Assuming that the target qubit is at the sweetspot, in order to measure crosstalk effects it is suggested to bias the qubit away.
Here is a possible runcard where we measure the crosstalk on qubit 2 caused by qubit 3 and 0.
Parameters#
- class qibocal.protocols.flux_dependence.qubit_crosstalk.QubitCrosstalkParameters(freq_width: int, freq_step: int, bias_width: ~typing.Optional[float] = None, bias_step: ~typing.Optional[float] = None, drive_amplitude: ~typing.Optional[float] = None, drive_duration: int = 2000, bias_point: ~typing.Optional[dict[typing.Union[int, str], float]] = <factory>, flux_qubits: ~typing.Optional[list[typing.Union[int, str]]] = None)[source]
Crosstalk runcard inputs.
- bias_point: Optional[dict[Union[int, str], float]]
bias_point_qubit_id}.
- Type:
Dictionary with {qubit_id
- flux_qubits: Optional[list[Union[int, str]]] = None
IDs of the qubits that we will sweep the flux on. If
None
flux will be swept on all qubits that we are running the routine on in a multiplex fashion. If given flux will be swept on the given qubits in a sequential fashion (n qubits will result to n different executions). Multiple qubits may be measured in each execution as specified by thequbits
option in the runcard.
- drive_amplitude: Optional[float] = None
Drive amplitude (optional). If defined, same amplitude will be used in all qubits. Otherwise the default amplitude defined on the platform runcard will be used
- drive_duration: int = 2000
Duration of the drive pulse.
- hardware_average: bool = False
By default hardware average will be performed.
- freq_width: int
Width for frequency sweep relative to the readout frequency [Hz].
- freq_step: int
Frequency step for sweep [Hz].
- nshots: int
Number of executions on hardware.
- relaxation_time: float
Wait time for the qubit to decohere back to the gnd state.
Example#
- id: qubit crosstalk
operation: qubit_crosstalk
targets: [2]
parameters:
bias_point:
2: 0.25
bias_step: 0.001
bias_width: 0.05
drive_amplitude: 0.002
drive_duration: 4000
flux_qubits: [0, 3]
freq_step: 200000
freq_width: 10000000
nshots: 1024
relaxation_time: 20000

The previous runcard aims at extracting the crosstalk coefficients \(C_{20}\) and \(C_{23}\).