Change Log#
Version 3.1#
Additions
GUI now includes functionality to plot coherence time estimates for various qubits
Under the hood
Speedup for diagonalization of Transmon and TunableTransmon by recognizing the Hamiltonian matrix as tridiagonal.
Version 3.0.3#
Bug fixes for GUI
get_operator_names has been eliminated from the operator dropdown menu
“State No.” sliders for FluxQubit, ZeroPi, and Cos2PhiQubit do not exclude the ground state anymore.
Fixed a bug where the plot was not being erased after switching to another qubit while in manual-update mode.
Changing to a non-manual scqubit now switches manual-mode off.
Fixed a bug where the maximum state number could be larger than hilbertdim.
Under the hood
Initialization of a circuit instance now does not globally switch to latex output (avoids unnecessary slowdowns with regular, non-sympy, output.
Version 3.0.2#
Additions
Circuit now implements multiprocessing in routines like get_evals_vs_paramvals when specifying num_cpus=2 or higher as optional keyword argument.
The class Circuit is now “frozen” to prevent accidental creation of new instance attributes. Doing <circuit instance>.non_existing_attribute = 3 will now raise an error message instead of creating a new attribute.
New threshold setting scqubits.settings.SYM_INVERSION_MAX_NODES (default: =3) decides whether the capacitance matrix is inverted symbolically (number of nodes ≤ threshold) or numerically (number of nodes > threshold). This avoids apparent hang-ups due to generation of massive symbolic expressions for matrix inverses.
Bug fixes
Branches are now distinguished by a unique id. This solves an issue of incorrect spanning trees when two branches of the same type were connected across the same set of nodes.
Fixed a bug in plotting routines which led to an Exception for cases with two or more layers in the system hierarchy.
Fixed a bug that could break Subsystem instances when the symbolic Hamiltonian had no potential terms.
GUI: establish correct clearing when turning manual plot on or when switching to another plot while on manual update.
Under the hood
All numerical diagonalization is now delayed until explicitly required. Changing circuit parameters thus does not incur a repeated runtime cost anymore.
When hierarchical diagonalization is used, the bare eigensystems for each subsystems are now stored and reused for calculations, and only replaced by a new set when necessary. This dramatically improves the performance of wavefunction plotting, identity wrapping, etc.
If the circuit parameters are not updated, successive diagonalizations are skipped for all subsystems.
Implemented eigsh_safe (wrapper for scipy.sparse.linalg.eigsh) that orthogonalizes the eigenvectors when degenerate eigenvalues are detected. In rare cases of actual degeneracies in the spectrum, sparse matrix methods could have given incorrect results because scipy.sparse.linalg.eigsh does not guarantee orthogonality of eigenvectors in degenerate subspaces.
Deprecations
The Circuit.from_yaml method will be phased out. Instead simply use the regular instance creation method scq.Circuit(…) with the same arguments as in the from_yaml class method.
Version 3.0.1#
Additions
Modified SymbolicCircuit and Circuit classes to simulate linear LC circuits efficiently.
Added the option grids_dict to plot_wavefunction, which provides an option to define a custom grid for wavefunction plots.
File input/output is now functional for the Circuit class, which will enable users to store Circuit objects to file.
Bug Fixes
sym_external_fluxes now functions as expected for circuits with capacitive sub-circuits; external fluxes are now distributed in a deterministic way by default.
Fixed and improved functions that display symbolic Hamiltonians, Lagrangians, potentials, etc.; added factor 2pi for displayed external fluxes to reflect units correctly.
Fixed the representation of cosine operator for periodic variables which previously resulted in an erroneous shift of pi in the wavefunction plots.
Multiple corrections to plot functionality of Circuit class.
GUI: fixed issue with “update” button for slow qubits.
GUI: fixed bad range default for wavefunction plots of fluxonium.
Under the Hood
Changed the way to calculate the junction potential matrix in Circuit class, which now uses expm to evaluate the cosine terms.
f-strings are now used for most of the string manipulations in Circuit and SymbolicCircuit class.
Fixed the overall energy shift in the eigenvalues by incorporating omega/2 for every harmonic oscillator.
Version 3.0#
Additions
Add circuit and symbolic_circuit modules, introducing the Circuit class for symbolic and numerical analysis of custom circuits
Add official support for Python 3.9 and 3.10
Improved GUI for single qubits (incl., e.g., a Dropdown menu with parameter choices from papers)
Improved Explorer class
Additional options for specifying initial and final states in transitions and plot_transitions inside ParameterSweep
Additional helper functions in ParameterSweep: get_subsys(index), subsys_by_id_str(id_str), subsys_evals_count(index), dressed_evals_count
ParameterSweep offers a new option ignore_low_overlap
Improved status information output when using parallel processing of ParameterSweep data
Deprecations
Remove deprecation support for outdated InteractionTerm / HilbertSpace interface
Remove deprecation support for outdated Explorer interface
Bug Fixes
Fixed incorrect output/return from supported_noise_channels for the FullZeroPi qubit
Fixed accidental support of h5py without safeguard (remains optional)
Fixed ordering bug in de-serialization of OrderedDict which could prevent reading of ParameterSweep objects
Fixed plotting issue in which presence of nans could reduce the intended plot range
Under the Hood
Remove _evec_dtype attribute from qubit classes
Eliminated code duplication for SpectrumLookup between HilbertSpace and ParameterSweep . Both classes now use SpectrumLookupMixin
ParameterSweep now has read-only property hilbertspace
Added quantitative pytest for FullZeroPi
Version 2.2.2#
- Bug Fixes
Fixed issue that could make import of scqubits fail when optional h5py package was not installed.
Plot options were not properly handled by plotting.data_vs_paramvals, leading to poor formatting of plot_dispersion_vs_paramvals
In certain scenarios (likely related to dependency version updates), GUI displays were duplicated rather than substituted.
Adjusted calculations mapping dressed-basis to bare-state labels: use (state overlap)^2 instead of (state overlap) for thresholding.
- Under the Hood
typing_extensions is new dependency (used for enhanced typing annotations such as @overload and Literal
Version 2.2#
- Bug Fixes
Use of <ParameterSweep>.plot_transitions could previously lead to a spurious switch of <ParameterSweep>[“evals”] to transition energies.
Include the +1/2 hbar omega term when diagonalizing fluxonium in the harmonic osc. basis. The omission of this only affected absolute energies, not the energy differences which are the relevant quantities in most cases. However, wavefunction plots for fluxonium were previously incorrectly positioned relative to the potential energy.
Some dispersion calculations previously failed for qubits other than Transmon and TunableTransmon.
Eliminated rare NamedSlotsNdarray indexing failure modes.
ParameterSweep previously failed for a “sweep” over just one parameter value.
Fixed issue where the depolarization time due to quasiparticle tunneling could be negative.
Fixed issue where accumulating legend label information in multiple plots to the same figure would fail to produce the desired legend.
- Additions
Support access to Figure, Axes objects from scq.GUI().
Support access to Figure, Axes from ParameterSweep.plot_transitions.
Support multi-photon transitions in ParameterSweep.transitions() and .plot_transitions() via new keyword argument photon_number
Added functionality for naming quantum system instances and interaction terms via id_str at initialization. This supports easier dict-like access to objects interior to ParameterSweep. Added deepcopy option to ParameterSweep that disconnects global variables from a deep copy saved inside ParameterSweep.
Refactored Explorer class for usage of new ParameterSweep
supported_noise_channels and effective_noise_channels are now @classmethods and can be called either directly through a class, or through a class instance.
t1_charge_impedance is no longer returned by effective_noise_channels in the case of a TunableTransmon and Transmon qubits
Added about function that shows basic information about scqubits as well as versions of some of the most important libraries that scqubits relies on.
Extended pytests for enhanced coverage.
- Deprecations
Old version of Explorer is still available with deprecation warning, but will be phased out in the future.
Deprecated omega parameter for Oscillator has been removed.
Version 2.1#
- Bug Fixes
Fixed a bug that overwrote <ParameterSweep>[“evals”] data with transition data when using plot_transitions().
Fixed proper integration of ParameterSweep into CentralDispatch, enabling proper warnings to the user when internal computed sweep data is out of sync with associated quantum system parameters.
Fixed a bug that could occur when a ParameterSweep was applied to a HilbertSpace object involving only a single subsystem.
- Under the Hood
Enable use of weakref in CentralDispatch for proper garbage collection.
Extended pytests to basic CentralDispatch functionality
Version 2.0#
- Additions
New graphical user interface
scqubits.GUI()
illustrating single-qubit functionality of scqubits.Introducing
NamedSlotsNdarray
as a convenient subclass of ndarray with name-based and value-based slicing, and immediate support for basic plotsAdded functionality for extracting dispersive energy parameters (such as Kerr coupling strengths)
Improved support for transition plots (subsystem transitions, sidebands etc.)
Added
Cos2PhiQubit
class.Added
KerrOscillator
classAdded
GenericQubit
(two-level system) so that toy models such as the Jaynes-Cummings model can be readily realized withHilbertSpace
.Added
n
andphi
operators to the Oscillator classAdded helper methods
convert_to_E_osc
andconvert_to_l_osc
forOscillator
initializationNew and enhanced interface for defining interaction terms in HilbertSpace objects via
.add_interaction()
Added option to input interaction as a
Qobj
, or specify interaction terms as string expressions; also represented inHilbertSpace.create()
GUI
- Improvements
Convergence for
ZeroPi
is now faster, thanks to a correction to the expression for the grid spacing in discretization.py.Refactored
ParameterSweep
class, now allowing for multi-dimensional parameter sweepsAdded a warning describing
total=True
being the default in t1 calculations
- Bug fixes
Fix to type conversion error affecting the
number
operator in operators.pyRectified orientation of
matrix2d
plots to match axes labelsmode
option for values displayed in matrix element plots was ignored
- Internals
New support for higher-order stencils in discretized derivatives.
Improved formatting of
__str__
methods (called when “printing” an scqubits class instance).Under the hood: use of Python 3.6 compatible type annotations; unified formatting enabled by the
black
packageImprovements to fileIO speeding up operations (increased memore cache) and requiring less disk space (avoid literal redundancies in stored data).
Version 1.3.2#
- Bug fixes
bug fix:
<qubit>.create()
failed in jupyter notebooks due to missing image filesbug fix: corrected the form of the quasiparticle noise operator
Version 1.3.1#
- Major changes/additions
Coherence calculations for the majority of qubits. These allow for estimating coherence times and rates due to various noise channels.
A new units system: users can specify energy units of their system Hamiltonian. These units are automatically considered when plotting and in coherence time calculations.
Separated documentation and example jupyter notebooks into individual repositories, see scqubits-doc and scqubits-examples.
- Minor changes/additions
Introduced tests for real-valuedness of zero-pi Hamiltonians (for speedup).
New options in plotting (e.g. grid).
- Bug fixes
Fixed bug preventing the proper disabling of the progress bar.
Various bug fixes and improvements of file IO operations.
Fixed issue with color legend bar in .plot_matrixelements.
Version 1.2.3#
Bug fix: the
FullZeroPi
Hamiltonian was incorrect in the case of nonzerodC
.improvement: thanks to adjusted ARPACK options, diagonalization should be noticeably faster for
ZeroPi
andFullZeroPi
.make
pathos
anddill
the default for multiprocessing.
Version 1.2.2#
Bug fix: implementation of the
add_hc=True
flag inInteractionTerm
involved a bug that could lead to incorrect resultsupdate to plotting routines now supports various extra plotting options such as
linestyle=...
etc.added
TunableTransmon
class for flux-tunable transmon, including junction asymmetrylimit support to Python >= 3.6
corrections to documentation of
FullZeroPi
added missing jupyter notebook illustrating use of
HilbertSpace
andParameterSweep
overhaul of file IO system now allows saving and loading various scqubit data via a custom h5 file format
ipywidget support for creating qubits inside jupyter (try, for example,
tmon = scqubits.Transmon.create()
)
Version 1.2.1#
update to the setup script to properly include testing data with the PyPi release.
Version 1.2#
- Major changes/additions
scqubits now offers multiprocessing support for a number of methods.
Introduced checks ensuring that umbrella objects like
HilbertSpace
andParameterSweep
instances do not accidentally go “out-of-sync” with respect to their basic components. When needed, warnings are thrown for the user to re-run sweeps or spectrum lookups.
- Under the hood:
Monitoring for changes of interdependent class instances is implemented through a central dispatch system. (disable:
settings.DISPATCH_ENABLED
)Removed
HilbertSpace
reference from within InteractionTerm (throws deprecation warning if still used)Made
HilbertSpace
inherit fromtuple
rather thanlist
; composition changes toHilbertSpace
warrant generating a newHilbertSpace
instanceShifted
InteractionTerm.hamiltonian
toHilbertSpace.interaction_hamiltonian
Created
DataStore
as general purpose parent class toSpectrumData
No longer store custom data inside
ParameterSweep
,sweep_generators.py
functions returnDataStore
objects
Version 1.1.1#
fixed a bug in display of
FluxQubit
wavefunctioninternal refactoring
Version 1.1.0#
new class
InteractionTerm
works in tandem withHilbertSpace
to ease setup of composite systems with pairwise interactionsnew
ParameterSweep
class efficiently generates spectral data for performing a scan of aHilbertSpace
object over an external parametersnew
Explorer
class introduces interactive plots (see docs and demo ipynb)cleaned up implementation of file Serializable operations