quchip.interop.eigenbasis

A frozen energy-basis device for third-party models without a native quchip model.

Classes

EigenbasisDevice(energies, *[, ...])

Represent a frozen source spectrum and its energy-basis operators.

class quchip.interop.eigenbasis.EigenbasisDevice(energies, *, charge_operator=None, phase_operator=None, levels=None, label=None, source_type=None, collapse_model='fermi_golden', coupling_channel=None, collapse_rate_threshold=1e-08, **noise)

Bases: BaseDevice

Represent a frozen source spectrum and its energy-basis operators.

You cannot differentiate through this snapshot with respect to the source circuit parameters.

Parameters:

• energies (array_like, shape (n,)) – Energy-ordered levels in GHz, with n >= 2. The device subtracts the first energy from every level.

• charge_operator (array_like, shape (n, n), or None) – Operators in the same source eigenbasis. None makes that drive channel unavailable. Capacitive couplings also use charge_operator, so they require it. The supplied matrix elements keep the source’s conventions.

• phase_operator (array_like, shape (n, n), or None) – Operators in the same source eigenbasis. None makes that drive channel unavailable. Capacitive couplings also use charge_operator, so they require it. The supplied matrix elements keep the source’s conventions.

• levels (int or None, default None) – Number of kept energy levels. None keeps all supplied levels.

• label (str or None, default None) – Device label. Defaults to a generated eigenbasis_<index>.

• source_type (str or None, default None) – Provenance label, such as "scqubits.ZeroPi".

• collapse_model ({"fermi_golden", "ladder"}, default "fermi_golden") – Relaxation from transition matrix elements or from an ideal ladder operator.

• coupling_channel ({"charge", "flux"} or None, default None) – Operator for matrix-element relaxation. "flux" uses phase_operator. Required when T1 is set with "fermi_golden".

• collapse_rate_threshold (float, default 1e-8) – Nonnegative cutoff on normalized downward-transition strengths.

• **noise (scalar or None) – T1 and T2 in ns, and dimensionless thermal_occupation. None omits the related channel. See BaseDevice for the noise constraints.

References

Blais et al., Rev. Mod. Phys. 93, 025005 (2021), https://doi.org/10.1103/RevModPhys.93.025005, for energy-basis operators and coupling to dissipative environments.

tunable_param_names: ClassVar[tuple[str, ...]] = ()

Parameters eligible for inverse design. DeviceModel derives these from declared fields unless the class or an ancestor supplies a tuple. Explicit tuples remain authoritative when inherited; an empty tuple excludes the device from inverse design. Plain BaseDevice subclasses default to an empty tuple without derivation.

dissipation(op, p)

Return the relaxation and dephasing channels for the stored spectrum.

Parameters:

• op (LocalOps) – Local operator namespace, unused because the stored matrices define the basis.

• p (parameter namespace) – Bound noise parameters for this calculation.

Returns:

Channels that collapse_model and the active noise parameters select.

Return type:

tuple of CollapseChannel

See also

EigenbasisDevice

Dissipation choices and physics reference.

unresolved_hamiltonian()

Return the frozen source spectrum as the authored Hamiltonian.

property freq: Any

Return the stored zero-to-one transition in GHz.

eigenenergies()

Return the stored ground-shifted energy table.

eigenvectors()

Return the identity map because the authored basis is energy ordered.

charge_coupling_operator()

Return the supplied charge-like operator in the authored basis.

phase_coupling_operator()

Return the supplied phase-like operator in the authored basis.

physics_notes()

Return human-readable declarations of this device’s approximations.

Each entry names a non-obvious assumption, approximation, or truncation of this device. Examples include “Hilbert truncation: 3 levels”, a model regime (Duffing), or a noise-channel selection (charge- vs flux-coupled T1).

The baseline entry is a truncation note, because every BaseDevice has some form of Hilbert-space truncation. A pure-dephasing note is added when T2 is set, because the number-operator dephasing model has non-obvious assumptions. Subclasses call super().physics_notes() and append their own model-specific notes.

to_dict()

Return a JSON-safe serialization. Subclasses extend it with their own parameters.

classmethod from_dict(data)

Restore a frozen device declaration.

Parameters:

data (dict) – Output of to_dict(), including the energies and optional operator matrices encoded as separate real and imaginary nested lists.

Returns:

Restored device with the noise and reference-frequency metadata.

Return type:

EigenbasisDevice