deltakit.circuit.noise_channels.Leakage#

class deltakit.circuit.noise_channels.Leakage(qubit: Qubit[T] | T, probability: float, *, tag: str | None = None)#

Bases: OneQubitOneProbabilityNoiseChannel[T]

The single qubit leakage channel.

Whether or not this noise channel fires is recorded in a leakage table that tracks across all shots whether or not qubits are leaked at a given point in the circuit. When a qubit is leaked a 1 is recorded in the leakage table and the qubit is moved to the maximally mixed state by applying X_ERROR(0.5) and Z_ERROR(0.5). That is, a depolarising model of leakage is implemented through this channel.

Leakage events are recorded and tracked so that the influence of leaked qubits on unleaked qubits across time and space can be accounted for. For example, if qubit 3 leaks and then a CX is performed on qubit 3 and 4, qubit 4 will also be fully depolarised.

All leakage introduced by the leakage channel is undone by reset gates. That is, reset returns qubits to the computational subspace.

This channel would typically be deployed alongside the RELAX channel which - in likeness of a reset gate - has the ability return a leaked qubit to the computational subspace.

Parameters:

qubit (Qubit[T] | T) – The qubit to apply leakage to.
probability (float) – A single float specifying the leakage probability.

Notes

Pauli Mixture:

1-p: no change to the qubit’s energy level, apply I p/4: record that the qubit has left the computational subspace, apply I p/4: record that the qubit has left the computational subspace, apply X p/4: record that the qubit has left the computational subspace, apply Y p/4: record that the qubit has left the computational subspace, apply Z

Methods#

`Leakage.approx_equals`	Determine whether two noise channels are equal within a given tolerance.
`Leakage.generator_from_prob`	Return a classmethod that can be used to create a noise channel with a predetermined probability
`Leakage.stim_targets`	Return all the stim targets which specifies this noise channel.
`Leakage.transform_qubits`	Transform this noise channel's qubits according to the id mapping.