System package

Submodules

Chip module

Component class and subclasses for the components making up the quantum device.

class c3.system.chip.Coupling(name, desc=None, comment=None, strength=None, connected=None, params=None, hamiltonian_func=None)

Bases: c3.system.chip.LineComponent

Represents a coupling behaviour between elements.

Parameters

• strength (np.float64) – coupling strength

• connected (list) – all physical components coupled via this specific coupling

get_Hamiltonian()

init_Hs(opers_list)

class c3.system.chip.Drive(**props)

Bases: c3.system.chip.LineComponent

Represents a drive line.

Parameters

connected (list) – all physical components receiving driving signals via this line

get_Hamiltonian()

init_Hs(ann_opers: list)

class c3.system.chip.LineComponent(**props)

Bases: c3.c3objs.C3obj

Represents the components connecting chip elements and drives.

Parameters

connected (list) – specifies the component that are connected with this line

asdict() → dict

class c3.system.chip.PhysicalComponent(**props)

Bases: c3.c3objs.C3obj

Represents the components making up a chip.

Parameters

hilbert_dim (int) – Dimension of the Hilbert space of this component

asdict() → dict

set_subspace_index(index)

class c3.system.chip.Qubit(name, hilbert_dim, desc=None, comment=None, freq=None, anhar=None, t1=None, t2star=None, temp=None, params=None)

Bases: c3.system.chip.PhysicalComponent

Represents the element in a chip functioning as qubit.

Parameters

• freq (np.float64) – frequency of the qubit

• anhar (np.float64) – anharmonicity of the qubit. defined as w01 - w12

• t1 (np.float64) – t1, the time decay of the qubit due to dissipation

• t2star (np.float64) – t2star, the time decay of the qubit due to pure dephasing

• temp (np.float64) – temperature of the qubit, used to determine the Boltzmann distribution of energy level populations

get_Hamiltonian()

Compute the Hamiltonian. Multiplies the number operator with the frequency and anharmonicity with the Duffing part and returns their sum.

Returns

Hamiltonian

Return type

tf.Tensor

get_Lindbladian(dims)

Compute the Lindbladian, based on relaxation, dephasing constants and finite temperature.

Returns

Hamiltonian

Return type

tf.Tensor

init_Hs(ann_oper)

Initialize the qubit Hamiltonians. If the dimension is higher than two, a Duffing oscillator is used.

Parameters

ann_oper (np.array) – Annihilation operator in the full Hilbert space

init_Ls(ann_oper)

Initialize Lindbladian components.

Parameters

ann_oper (np.array) – Annihilation operator in the full Hilbert space

class c3.system.chip.Resonator(**props)

Bases: c3.system.chip.PhysicalComponent

Represents the element in a chip functioning as resonator.

Parameters

freq (np.float64) – frequency of the resonator

get_Hamiltonian()

Compute the Hamiltonian.

get_Lindbladian(dims)

NOT IMPLEMENTED

init_Hs(ann_oper)

Initialize the Hamiltonian as a number operator

Parameters

ann_oper (np.array) – Annihilation operator in the full Hilbert space.

init_Ls(ann_oper)

NOT IMPLEMENTED

class c3.system.chip.SNAIL(name: str, desc: str = ' ', comment: str = ' ', hilbert_dim: int = 4, freq: numpy.float64 = 0.0, anhar: numpy.float64 = 0.0, beta: numpy.float64 = 0.0, t1: numpy.float64 = 0.0, t2star: numpy.float64 = 0.0, temp: numpy.float64 = 0.0)

Bases: c3.system.chip.PhysicalComponent

Represents the element in a chip functioning as a three wave mixing element also knwon as a SNAIL. Reference: https://arxiv.org/pdf/1702.00869.pdf :param freq: frequency of the qubit :type freq: np.float64 :param anhar: anharmonicity of the qubit. defined as w01 - w12 :type anhar: np.float64 :param beta: third order non_linearity of the qubit. :type beta: np.float64 :param t1: t1, the time decay of the qubit due to dissipation :type t1: np.float64 :param t2star: t2star, the time decay of the qubit due to pure dephasing :type t2star: np.float64 :param temp: temperature of the qubit, used to determine the Boltzmann distribution

of energy level populations

Parameters

• is mostly an exact copy of the Qubit class. The only difference is the added third order non linearity with a prefactor beta. (Class) –

• only modification is the get hamiltonian and init hamiltonian definition. Also imported the necessary third order non linearity (The) –

• the hamiltonian library. (from) –

get_Hamiltonian()

Compute the Hamiltonian. Multiplies the number operator with the frequency and anharmonicity with the Duffing part and returns their sum. :returns: Hamiltonian :rtype: tf.Tensor

get_Lindbladian(dims)

Compute the Lindbladian, based on relaxation, dephasing constants and finite temperature.

Returns

Hamiltonian

Return type

tf.Tensor

init_Hs(ann_oper)

Initialize the SNAIL Hamiltonians. :param ann_oper: Annihilation operator in the full Hilbert space :type ann_oper: np.array

init_Ls(ann_oper)

Initialize Lindbladian components.

Parameters

ann_oper (np.array) – Annihilation operator in the full Hilbert space

class c3.system.chip.Transmon(name: str, desc: str = ' ', comment: str = ' ', hilbert_dim: int = 2, freq: numpy.float64 = 0.0, phi: numpy.float64 = 0.0, phi_0: numpy.float64 = 0.0, gamma: numpy.float64 = None, d: numpy.float64 = None, t1: numpy.float64 = 0.0, t2star: numpy.float64 = 0.0, temp: numpy.float64 = 0.0, anhar: numpy.float64 = 0.0)

Bases: c3.system.chip.PhysicalComponent

Represents the element in a chip functioning as tunanble transmon qubit.

Parameters

• freq (np.float64) – base frequency of the Transmon

• phi_0 (np.float64) – half period of the phase dependant function

• phi (np.float64) – flux position

get_Hamiltonian()

get_Lindbladian(dims)

Compute the Lindbladian, based on relaxation, dephasing constants and finite temperature.

Returns

Hamiltonian

Return type

tf.Tensor

get_anhar()

get_factor()

get_freq()

init_Hs(ann_oper)

init_Ls(ann_oper)

Initialize Lindbladian components.

Parameters

ann_oper (np.array) – Annihilation operator in the full Hilbert space

c3.system.chip.dev_reg_deco(func)

Decorator for making registry of functions

Model module

The model class, containing information on the system and its modelling.

class c3.system.model.Model(subsystems=None, couplings=None, tasks=None)

Bases: object

What the theorist thinks about from the system.

Class to store information about our system/problem/device. Different models can represent the same system.

Parameters

• subsystems (list) – List of individual, non-interacting physical components like qubits or resonators

• couplings (list) – List of interaction operators between subsystems, like couplings or drives.

• tasks (list) – Badly named list of processing steps like line distortions and read out modeling

H0

Type

class

Drift Hamiltonian

asdict() → dict

Return a dictionary compatible with config files.

get_Frame_Rotation(t_final: numpy.float64, freqs: dict, framechanges: dict)

Compute the frame rotation needed to align Lab frame and rotating Eigenframes of the qubits.

Parameters

• t_final (tf.float64) – Gate length

• freqs (list) – Frequencies of the local oscillators.

• framechanges (list) – List of framechanges. A phase shift applied to the control signal to compensate relative phases of drive oscillator and qubit.

Returns

A (diagonal) propagator that adjust phases

Return type

tf.Tensor

get_Hamiltonians()

get_Lindbladians()

get_dephasing_channel(t_final, amps)

Compute the matrix of the dephasing channel to be applied on the operation.

Parameters

• t_final (tf.float64) – Duration of the operation.

• amps (dict of tf.float64) – Dictionary of average amplitude on each drive line.

Returns

Matrix representation of the dephasing channel.

Return type

tf.tensor

get_qubit_freqs()

list_parameters()

read_config(filepath: str) → None

Load a file and parse it to create a Model object.

Parameters

filepath (str) – Location of the configuration file

set_FR(use_FR)

Setter for the frame rotation option for adjusting the individual rotating frames of qubits when using gate sequences

set_components(subsystems, couplings=None) → None

set_dephasing_strength(dephasing_strength)

set_dressed(dressed)

Go to a dressed frame where static couplings have been eliminated.

Parameters

dressed (boolean) –

set_lindbladian(lindbladian)

Set whether to include open system dynamics.

Parameters

lindbladian (boolean) –

set_tasks(tasks) → None

update_Hamiltonians()

Recompute the matrix representations of the Hamiltonians.

update_Lindbladians()

Return Lindbladian operators and their prefactors.

update_dressed(ordered=True)

Compute the Hamiltonians in the dressed basis by diagonalizing the drift and applying the resulting transformation to the control Hamiltonians.

update_drift_eigen(ordered=True)

Compute the eigendecomposition of the drift Hamiltonian and store both the Eigenenergies and the transformation matrix.

update_model(ordered=True)

write_config(filepath: str) → None

Write dictionary to a HJSON file.

Tasks module

class c3.system.tasks.ConfusionMatrix(name: str = 'conf_matrix', desc: str = ' ', comment: str = ' ', **confusion_rows)

Bases: c3.system.tasks.Task

Allows for misclassificaiton of readout measurement.

confuse(pops)

Apply the confusion (or misclassification) matrix to populations.

Parameters

pops (list) – Populations

Returns

Populations after misclassification.

Return type

list

class c3.system.tasks.InitialiseGround(name: str = 'init_ground', desc: str = ' ', comment: str = ' ', init_temp: c3.c3objs.Quantity = None)

Bases: c3.system.tasks.Task

Initialise the ground state with a given thermal distribution.

initialise(drift_H, lindbladian=False, init_temp=None)

Prepare the initial state of the system. At the moment finite temperature requires open system dynamics.

Parameters

• drift_H (tf.Tensor) – Drift Hamiltonian.

• lindbladian (boolean) – Whether to include open system dynamics. Required for Temperature > 0.

• init_temp (Quantity) – Temperature of the device.

Returns

State or density vector

Return type

tf.Tensor

class c3.system.tasks.MeasurementRescale(name: str = 'meas_rescale', desc: str = ' ', comment: str = ' ', meas_offset: c3.c3objs.Quantity = None, meas_scale: c3.c3objs.Quantity = None)

Bases: c3.system.tasks.Task

Rescale the result of the measurements. This is usually done to account for preparation errors.

Parameters

• meas_offset (Quantity) – Offset added to the measured signal.

• meas_scale (Quantity) – Factor multiplied to the measured signal.

rescale(pop1)

Apply linear rescaling and offset to the readout value.

Parameters

pop1 (tf.float64) – Population in first excited state.

Returns

Population after rescaling.

Return type

tf.float64

class c3.system.tasks.Task(name: str = ' ', desc: str = ' ', comment: str = ' ')

Bases: c3.c3objs.C3obj

Task that is part of the measurement setup.

Module contents