ParameterSweepBase#

class scqubits.core.param_sweep.ParameterSweepBase(*args, **kwds)[source]#

The_ParameterSweepBase class is an abstract base class for ParameterSweep and StoredSweep

Methods

`ParameterSweepBase.__init__`(args, *kwargs)
`ParameterSweepBase.add_matelem_sweep`(...[, ...])	Generate data for matrix elements with respect to a given operator, as a function of the sweep parameter(s)
`ParameterSweepBase.add_sweep`(sweep_function)	Add a new sweep to the ParameterSweep object.
`ParameterSweepBase.all_params_fixed`(...)	Checks whether the indices provided fix all the parameters.
`ParameterSweepBase.bare_eigenstates`(subsys)	Return ndarray of bare eigenstates for given subsystems and parameter index.
`ParameterSweepBase.bare_eigenvals`(subsys[, ...])	Return NamedSlotsNdarray of bare eigenenergies for given subsystem, usually to be used with preslicing.
`ParameterSweepBase.bare_index`(dressed_index)	For given dressed index, look up the corresponding bare index.
`ParameterSweepBase.bare_productstate`(bare_index)	Return the bare product state specified by bare_index.
`ParameterSweepBase.dressed_evals_count`()	Returns number of dressed eigenvalues included in sweep.
`ParameterSweepBase.dressed_index`(bare_labels)	For given bare product state return the corresponding dressed-state index.
`ParameterSweepBase.eigensys`([param_indices])	Return the list of dressed eigenvectors
`ParameterSweepBase.eigenvals`([param_indices])	Return the array of dressed eigenenergies - primarily for running the sweep
`ParameterSweepBase.energy_by_bare_index`(...)	Look up dressed energy most closely corresponding to the given bare-state labels
`ParameterSweepBase.energy_by_dressed_index`(...)	Look up the dressed eigenenergy belonging to the given dressed index, usually to be used with pre-slicing
`ParameterSweepBase.generate_lookup`()	For each parameter value of the parameter sweep, generate the map between bare states and dressed states.
`ParameterSweepBase.get_subsys`(index)	rtype `QuantumSystem`
`ParameterSweepBase.get_subsys_index`(subsys)	rtype `int`
`ParameterSweepBase.get_sweep_indices`(multi_index)	For given generalized multi-index, return a list of the indices that are being swept.
`ParameterSweepBase.keys`()
`ParameterSweepBase.plot_transitions`([...])	Plot transition energies as a function of one external parameter.
`ParameterSweepBase.receive`(event, sender, ...)	Hook to CENTRAL_DISPATCH.
`ParameterSweepBase.set_npindextuple`([...])	rtype `Tuple`[`Union`[`int`, `slice`, `Tuple`[`int`], `List`[`int`]], `...`]
`ParameterSweepBase.set_update_func`(...)	Account for the two possible signatures of the update_hilbertspace function.
`ParameterSweepBase.subsys_by_id_str`(id_str)	rtype `QuantumSystem`
`ParameterSweepBase.subsys_evals_count`(...)	rtype `int`
`ParameterSweepBase.transitions`([...])	Use dressed eigenenergy data and lookup based on bare product state labels to extract transition energy data.

Attributes

`bare_specdata_list`	Wrap bare eigensystem data into a SpectrumData object.
`dressed_specdata`	Wrap dressed eigensystem data into a SpectrumData object.
`hilbertspace`
`osc_subsys_list`
`param_info`	Return a dictionary of the parameter names and values used in this sweep.
`parameters`	Return the Parameter object (access parameter values/indexing)
`qbt_subsys_list`
`subsystem_count`
`system_params`

add_matelem_sweep(operator, sweep_name, subsystem=None)[source]#

Generate data for matrix elements with respect to a given operator, as a function of the sweep parameter(s)

Parameters

operator (Union[str, Qobj]) – name of the operator in question (str), or full operator in Qobj form
sweep_name (str) – The sweep data will be accessible as <ParameterSweep>[<sweep_name>]
subsystem (Optional[QuantumSystem]) – subsystems for which to compute matrix elements, required if operator is given in str form

Return type

None

Returns

None; results are saved as <ParameterSweep>[<sweep_name>]

add_sweep(sweep_function, sweep_name=None, **kwargs)[source]#

Add a new sweep to the ParameterSweep object. The generated data is subsequently accessible through <ParameterSweep>[<sweep_function>] or <ParameterSweep>[<sweep_name>]

Parameters

sweep_function (Union[str, Callable]) – name of a sweep function in scq.sweeps as str, or custom function ( callable) provided by the user
sweep_name (Optional[str]) – if given, the generated data is stored in <ParameterSweep>[<sweep_name>] rather than [<sweep_name>]
kwargs – keyword arguments handed over to the sweep function

Return type

None

Returns

None

all_params_fixed(param_indices)#

Checks whether the indices provided fix all the parameters.

Parameters: param_indices (Union[slice, tuple]) – Tuple or slice fixing all or a subset of the parameters.
Return type: bool
Returns: True if all parameters are being fixed by param_indices.

bare_eigenstates(subsys, param_indices=None)#

Return ndarray of bare eigenstates for given subsystems and parameter index. Eigenstates are expressed in the basis internal to the subsystems. Usually to be with pre-slicing.

Return type

NamedSlotsNdarray

Parameters

subsys (Union[QubitBaseClass, Oscillator, KerrOscillator, GenericQubit]) –
param_indices (Optional[Tuple[int, ...]]) –

bare_eigenvals(subsys, param_indices=None)#

Return NamedSlotsNdarray of bare eigenenergies for given subsystem, usually to be used with preslicing.

Parameters

subsys (Union[QubitBaseClass, Oscillator, KerrOscillator, GenericQubit]) – Hilbert space subsystem for which bare eigendata is to be looked up
param_indices (Optional[Tuple[int, ...]]) – position indices of parameter values in question

Return type

NamedSlotsNdarray

Returns

bare eigenenergies for the specified subsystem and the external parameter fixed to the value indicated by its index

bare_index(dressed_index, param_indices=None)#

For given dressed index, look up the corresponding bare index.

Return type

Optional[Tuple[int, ...]]

Returns

Bare state specification in tuple form. Example: (1,0,3) means subsystem 1 is in bare state 1, subsystem 2 in bare state 0, and subsystem 3 in bare state 3.

Parameters

dressed_index (int) –
param_indices (Optional[Tuple[int, ...]]) –

bare_productstate(bare_index)#

Return the bare product state specified by bare_index. Note: no parameter dependence here, since the Hamiltonian is always represented in the bare product eigenbasis.

Parameters: bare_index (Tuple[int, ...]) –
Return type: Qobj
Returns: ket in full Hilbert space

property bare_specdata_list: List[SpectrumData]#

Wrap bare eigensystem data into a SpectrumData object. To be used with pre-slicing, e.g. <ParameterSweep>[0, :].bare_specdata_list

Return type: List of SpectrumData objects with bare eigensystem data, one per subsystem

dressed_evals_count()[source]#

Returns number of dressed eigenvalues included in sweep.

Return type: int

dressed_index(bare_labels, param_indices=None)#

For given bare product state return the corresponding dressed-state index.

Parameters

bare_labels (Tuple[int, ...]) – bare_labels = (index, index2, …)
param_indices (Union[int, slice, Tuple[int], List[int], Tuple[Union[int, slice, Tuple[int], List[int]], ...], None]) – indices of parameter values of interest

Return type

Union[ndarray, int, None]

Returns

dressed state index closest to the specified bare state

property dressed_specdata: SpectrumData#

Wrap dressed eigensystem data into a SpectrumData object. To be used with pre-slicing, e.g. <ParameterSweep>[0, :].dressed_specdata

Return type: SpectrumData object with bare eigensystem data

eigensys(param_indices=None)#

Return the list of dressed eigenvectors

Parameters: param_indices (Optional[Tuple[int, ...]]) – position indices of parameter values in question
Return type: ndarray
Returns: dressed eigensystem for the external parameter fixed to the value indicated by the provided index

eigenvals(param_indices=None)#

Return the array of dressed eigenenergies - primarily for running the sweep

Parameters

question (position indices of parameter values in) –
param_indices (Optional[Tuple[int, ...]]) –

Return type

ndarray

Returns

dressed eigenenergies for the external parameters fixed to the values indicated by the provided indices

energy_by_bare_index(bare_tuple, subtract_ground=False, param_indices=None)#

Look up dressed energy most closely corresponding to the given bare-state labels

Parameters

bare_tuple (Tuple[int, ...]) – bare state indices
subtract_ground (bool) – whether to subtract the ground state energy
param_indices (Union[int, slice, Tuple[int], List[int], Tuple[Union[int, slice, Tuple[int], List[int]], ...], None]) – indices specifying the set of parameters

Return type

NamedSlotsNdarray

Returns

dressed energies, if lookup successful, otherwise nan;

energy_by_dressed_index(dressed_index, subtract_ground=False, param_indices=None)#

Look up the dressed eigenenergy belonging to the given dressed index, usually to be used with pre-slicing

Parameters

dressed_index (int) – index of dressed state of interest
subtract_ground (bool) – whether to subtract the ground state energy
param_indices (Optional[Tuple[int, ...]]) – specifies the desired choice of parameter values

Return type

float

Returns

dressed energy

generate_lookup()#

For each parameter value of the parameter sweep, generate the map between bare states and dressed states.

Return type: NamedSlotsNdarray
Returns: each list item is a list of dressed indices whose order corresponds to the ordering of bare indices (as stored in .canonical_bare_labels, thus establishing the mapping)

get_sweep_indices(multi_index)[source]#

For given generalized multi-index, return a list of the indices that are being swept.

Return type: List[int]
Parameters: multi_index (Tuple[Union[int, float, complex, slice, Tuple[int], List[int]], ...]) –

property param_info: Dict[str, ndarray]#: Return a dictionary of the parameter names and values used in this sweep.

property parameters: Parameters#: Return the Parameter object (access parameter values/indexing)

plot_transitions(subsystems=None, initial=None, final=None, sidebands=False, photon_number=1, make_positive=True, coloring='transition', param_indices=None, **kwargs)[source]#

Plot transition energies as a function of one external parameter. Usage is based on preslicing of the ParameterSweep object to select a single parameter to be involved in the sweep. E.g.,

<ParameterSweep>[0, :, 2].plot_transitions()

plots all eigenenergy differences for transitions starting in the ground state (default when no initial state is specified) as a function of the middle parameter while parameters 1 and 3 are fixed by the indices 0 and 2.

Parameters

subsystems (Union[QuantumSystem, List[QuantumSystem], None]) – single subsystems or list of subsystems considered as “active” for the transitions to be generated; if omitted as a parameter, all subsystems are considered as actively participating in the transitions
initial (Union[int, Tuple[int, ...], None]) – initial state from which transitions originate: the initial state can either be specified as a tuple referring to a bare product state, or as an integer representing the dressed state index. For bare product states, the required tuple has as many entries as the underlying HilbertSpace object has subsystems. (If subsystems is given, then the tuple may be reduced to entries for just these subsystems; other subsystems are given a “0” entry automatically.) The dressed state corresponding to the given bare product state is determined by considerations of overlaps. Note: for an initial dressed state, the sidebands option is ignored.
final (Union[int, Tuple[int, ...], None]) – concrete final state for which the transition energy should be generated, given either as a bare product state (tuple of excitation numbers), or as a dressed state (non-negative integer). If final is omitted a list of final states is generated for dispersive transitions within each (active) subsystem. Sidebands can be switched on with the subsequent keyword option. final=-1 can be chosen for a final state list to all other dressed states (helpful when the dispersive limit breaks down).
sidebands (bool) – if set to true, sideband transitions with multiple subsystems changing excitation levels are included (default: False). This option is ignored if initial is given as an integer dressed state index.
photon_number (int) – number of photons involved in transition; transition frequencies are divided by this number (default: photon_number=1, i.e., single-photon transitions)
make_positive (bool) – boolean option relevant if the initial state is an excited state; downwards transition energies would regularly be negative, but are converted to positive if this flag is set to True (default: True)
coloring (Union[str, ndarray]) – For “transition” (default), transitions are colored by their dispersive nature; for “plain” no selective highlighting is attempted.
param_indices (Union[int, slice, Tuple[int], List[int], Tuple[Union[int, slice, Tuple[int], List[int]], ...], None]) – usually to be omitted, as param_indices will be set via pre-slicing

Return type

Tuple[Figure, Axes]

Returns

Plot Figure and Axes objects

receive(event, sender, **kwargs)[source]#

Hook to CENTRAL_DISPATCH. This method is accessed by the global CentralDispatch instance whenever an event occurs that ParameterSweep is registered for. In reaction to update events, the lookup table is marked as out of sync.

Parameters

event (str) – type of event being received
sender (object) – identity of sender announcing the event
**kwargs –

Return type

None

set_update_func(update_hilbertspace)[source]#

Account for the two possible signatures of the update_hilbertspace function. Inspect whether a self argument is given. If not, return a function that accepts self as a dummy argument.

Return type: Callable
Parameters: update_hilbertspace (Callable) –

transitions(as_specdata=False, subsystems=None, initial=None, final=None, sidebands=False, photon_number=1, make_positive=False, param_indices=None)[source]#

Use dressed eigenenergy data and lookup based on bare product state labels to extract transition energy data. Usage is based on preslicing to select all or a subset of parameters to be involved in the sweep, e.g.,

<ParameterSweep>[0, :, 2].transitions()

produces all eigenenergy differences for transitions starting in the ground state (default when no initial state is specified) as a function of the middle parameter while parameters 1 and 3 are fixed by the indices 0 and 2.

Parameters

subsystems (Union[QuantumSystem, List[QuantumSystem], None]) – single subsystems or list of subsystems considered as “active” for the transitions to be generated; if omitted as a parameter, all subsystems are considered as actively participating in the transitions
initial (Union[int, Tuple[int, ...], None]) – initial state from which transitions originate, specified either (1) as a bare product state (tuple of excitation numbers of all subsystems or of the active ones given in subsystems); or (2) as a dressed-state index in the form of an integer >= 0. (default: (0,0,…,0) which is usually closest to the ground state)
final (Union[int, Tuple[int, ...], None]) – concrete final state for which the transition energy should be generated, given either as a bare product state (tuple of excitation numbers), or as a dressed state (non-negative integer). If final is omitted a list of final states is generated for dispersive transitions within each (active) subsystem. Sidebands can be switched on with the subsequent keyword option. final=-1 can be chosen for a final state list to all other dressed states (helpful when the dispersive limit breaks down).
sidebands (bool) – if set to true, sideband transitions with multiple subsystems changing excitation levels are included (default: False)
photon_number (int) – number of photons involved in transition; transition frequencies are divided by this number (default: photon_number=1, i.e., single-photon transitions)
make_positive (bool) – boolean option relevant if the initial state is an excited state; downwards transition energies would regularly be negative, but are converted to positive if this flag is set to True
as_specdata (bool) – whether data is handed back in raw array form or wrapped into a SpectrumData object (default: False)
param_indices (Union[int, slice, Tuple[int], List[int], Tuple[Union[int, slice, Tuple[int], List[int]], ...], None]) – usually to be omitted, as param_indices will be set via pre-slicing

Return type

Union[Tuple[List[Tuple[Union[int, Tuple[int, ...]], Union[int, Tuple[int, ...]]]], List[NamedSlotsNdarray]], SpectrumData]

Returns

A tuple consisting of a list of all the transitions and a corresponding list of difference energies, e.g. ((0,0,0), (0,0,1)), <energy array for transition 0,0,0 -> 0,0,1>. If as_specdata is set to True, a SpectrumData object is returned instead, saving transition label info in an attribute named labels.