laboneq_applications.experiments.echo

This module defines the Hahn echo experiment.

In the Hahn echo experiment, we perform a Ramsey experiment and place one extra refocusing pulse, typically y180, between the two x90 pulses. Due to this additional pulse, the quasi-static contributions to dephasing can be “refocused” and by that the experiment is less sensitive to quasi-static noise.

The pulses are generally chosen to be resonant with the qubit transition for a Hahn echo, since any frequency detuning would be nominally refocused anyway.

The Hahn echo experiment has the following pulse sequence:

qb --- [ prep transition ] --- [ x90_transition ] --- [ delay/2 ] ---
[ refocusing pulse ] --- [ delay/2 ] --- [ x90_transition ] --- [ measure ]

If multiple qubits are passed to the experiment workflow, the above pulses are applied in parallel on all the qubits.

EchoExperimentOptions

Options for the Hahn echo experiment.

Additional attributes

refocus_pulse: String to define the quantum operation in-between the x90 pulses. Default: "y180".

refocus_qop = workflow.option_field('y180', description='String to define the quantum operation in-between the x90 pulses') class-attribute instance-attribute

create_experiment(qpu, qubits, delays, options=None)

Creates a Hahn echo Experiment.

Parameters:

Name	Type	Description	Default
qpu	QPU	The qpu consisting of the original qubits and quantum operations.	required
qubits	QuantumElements	The qubits on which to run the experiments. May be either a single qubit or a list of qubits.	required
delays	QubitSweepPoints	The delays to sweep over for each qubit. The delays between the two x90 pulses and the refocusing pulse are delays / 2; see the schematic of the pulse sequence at the top of the file. Note that delays must be identical for qubits that use the same measure port.	required
options	EchoExperimentOptions | None	The options for building the workflow as an instance of [EchoExperimentOptions], inheriting from [TuneupExperimentOptions]. See the docstrings of these classes for more details.	None

Returns:

Name	Type	Description
Experiment	Experiment	The generated LabOne Q Experiment instance to be compiled and executed.

Raises:

Type	Description
ValueError	If the conditions in validation.validate_and_convert_qubits_sweeps are not fulfilled.
ValueError	If the experiment uses calibration traces and the averaging mode is sequential.

Example

options = TuneupExperimentOptions()
options.count = 10
options.cal_traces = True
setup = DeviceSetup("my_device")
qpu = QPU(
    quantum_elements=[TunableTransmonQubit("q0"), TunableTransmonQubit("q1")],
    quantum_operations=TunableTransmonOperations(),
)
temp_qubits = qpu.copy_quantum_elements()
create_experiment(
    qpu=qpu,
    qubits=temp_qubits,
    delays=[np.linspace(0, 30e-6, 51), np.linspace(0, 30e-6, 51)],
    options=options,
)

experiment_workflow(session, qpu, qubits, delays, temporary_parameters=None, options=None)

The Hahn echo experiment workflow.

The workflow consists of the following steps:

• create_experiment
• compile_experiment
• run_experiment
• analysis_workflow
• update_qubits

Parameters:

Name	Type	Description	Default
session	Session	The connected session to use for running the experiment.	required
qpu	QPU	The qpu consisting of the original qubits and quantum operations.	required
qubits	QuantumElements	The qubits on which to run the experiments. May be either a single qubit or a list of qubits.	required
delays	QubitSweepPoints	The delays to sweep over for each qubit. The delays between the two x90 pulses and the refocusing pulse are delays / 2; see the schematic of the pulse sequence at the top of the file. Note that delays must be identical for qubits that use the same measure port.	required
temporary_parameters	dict[str | tuple[str, str, str], dict | QuantumParameters] | None	The temporary parameters with which to update the quantum elements and topology edges. For quantum elements, the dictionary key is the quantum element UID. For topology edges, the dictionary key is the edge tuple (tag, source node UID, target node UID).	None
options	TuneUpWorkflowOptions | None	The options for building the workflow as an instance of [TuneUpWorkflowOptions]. See the docstrings of this class for more details.	None

Returns:

Name	Type	Description
WorkflowBuilder	None	The builder for the experiment workflow.

Example

options = EchoWorkflowOptions()
options.count(10)
options.transition("ge")
qpu = QPU(
    quantum_elements=[TunableTransmonQubit("q0"), TunableTransmonQubit("q1")],
    quantum_operations=TunableTransmonOperations(),
)
temp_qubits = qpu.copy_quantum_elements()
result = run(
    session=session,
    qpu=qpu,
    qubits=temp_qubits,
    delays=[np.linspace(0, 30e-6, 51), np.linspace(0, 30e-6, 51)],
    options=options,
)