Change Log¶

Improvements¶

• Added a “Citing QuTiP” section to the README, containing a link to the QuTiP papers. (#1554)

• Added entropy_relative which returns the quantum relative entropy between two density matrices. (#1553)

Bug Fixes¶

• Fixed Bloch sphere distortion when using Matplotlib >= 3.3.0. (#1496)

• Removed use of integer-like floats in math.factorial since it is deprecated as of Python 3.9. (#1550)

• Simplified call to ffmpeg used in the the Bloch sphere animation tutorial to work with recent versions of ffmpeg. (#1557)

• Removed blitting in Bloch sphere FuncAnimation example. (#1558)

• Added a version checking condition to handle specific functionalities depending on the matplotlib version. (#1556)

• Fixed mesolve handling of time-dependent Hamiltonian with a custom tlist and c_ops. (#1561)

Developer Changes¶

• Read documentation version and release from the VERSION file.

Improvements¶

• Add the [full] pip install target (by Jake Lishman)

Bug Fixes¶

• Work around pointer MKL eigh bug in SciPy <= 1.4 (by Felipe Bivort Haiek)

• Fix berkeley, swapalpha and cz gate operations (by Boxi Li)

• Expose the CPHASE control gate (by Boxi Li)

• Fix building from the sdist when git is not installed (by Jake Lishman)

Developer Changes¶

• Move the qutip-doc documentation into the qutip repository (by Jake Lishman)

• Fix warnings in documentation build (by Jake Lishman)

• Fix warnings in pytest runs and make pytest treat warnings as errors (by Jake Lishman)

• Add Simon Cross as author (by Simon Cross)

Improvements¶

• MAJOR Add saving, loading and resetting functionality to qutip.settings for easy re-configuration. (by Eric Giguère)

• MAJOR Add a quantum gate scheduler in qutip.qip.scheduler, to help parallelise the operations of quantum gates. This supports two scheduling modes: as late as possible, and as soon as possible. (by Boxi Li)

• MAJOR Improved qubit circuit simulators, including OpenQASM support and performance optimisations. (by Sidhant Saraogi)

• MAJOR Add tools for quantum measurements and their statistics. (by Simon Cross and Sidhant Saraogi)

• Add support for Numpy 1.20. QuTiP should be compiled against a version of Numpy >= 1.16.6 and < 1.20 (note: does _not_ include 1.20 itself), but such an installation is compatible with any modern version of Numpy. Source installations from pip understand this constraint.

• Improve the error message when circuit plotting fails. (by Boxi Li)

• Add support for parsing M1 Mac hardware information. (by Xiaoliang Wu)

• Add more single-qubit gates and controlled gates. (by Mateo Laguna and Martín Sande Costa)

• Support decomposition of X, Y and Z gates in circuits. (by Boxi Li)

• Refactor QubitCircuit.resolve_gate() (by Martín Sande Costa)

Bug Fixes¶

• Fix dims in the returns from Qobj.eigenstates on superoperators. (by Jake Lishman)

• Calling Numpy ufuncs on Qobj will now correctly raise a TypeError rather than returning a nonsense ndarray. (by Jake Lishman)

• Convert segfault into Python exception when creating too-large tensor products. (by Jake Lishman)

• Correctly set num_collapse in the output of mesolve. (by Jake Lishman)

• Fix ptrace when all subspaces are being kept, or the subspaces are passed in order. (by Jake Lishman)

• Fix sorting bug in Bloch3d.add_points(). (by pschindler)

• Fix invalid string literals in docstrings and some unclosed files. (by Élie Gouzien)

• Fix Hermicity tests for matrices with values that are within the tolerance of 0. (by Jake Lishman)

• Fix the trace norm being incorrectly reported as 0 for small matrices. (by Jake Lishman)

• Fix issues with dnorm when using CVXPy 1.1 with sparse matrices. (by Felipe Bivort Haiek)

• Fix segfaults in mesolve when passed a bad initial Qobj as the state. (by Jake Lishman)

• Fix sparse matrix construction in PIQS when using Scipy 1.6.1. (by Drew Parsons)

• Fix zspmv_openmp.cpp missing from the pip sdist. (by Christoph Gohlke)

• Fix correlation functions throwing away imaginary components. (by Asier Galicia Martinez)

• Fix QubitCircuit.add_circuit() for SWAP gate. (by Canoming)

• Fix the broken LaTeX image conversion. (by Jake Lishman)

• Fix gate resolution of the FREDKIN gate. (by Bo Yang)

• Fix broken formatting in docstrings. (by Jake Lishman)

Deprecations¶

• eseries, essolve and ode2es are all deprecated, pending removal in QuTiP 5.0. These are legacy functions and classes that have been left unmaintained for a long time, and their functionality is now better achieved with QobjEvo or mesolve.

Developer Changes¶

• MAJOR Overhaul of setup and packaging code to make it satisfy PEP 517, and move the build to a matrix on GitHub Actions in order to release binary wheels on pip for all major platforms and supported Python versions. (by Jake Lishman)

• Default arguments in Qobj are now None rather than mutable types. (by Jake Lishman)

• Fixed comsumable iterators being used to parametrise some tests, preventing the testing suite from being re-run within the same session. (by Jake Lishman)

• Remove unused imports, simplify some floats and remove unnecessary list conversions. (by jakobjakobson13)

• Improve Travis jobs matrix for specifying the testing containers. (by Jake Lishman)

• Fix coverage reporting on Travis. (by Jake Lishman)

• Added a pyproject.toml file. (by Simon Humpohl and Eric Giguère)

• Add doctests to documentation. (by Sidhant Saraogi)

• Fix all warnings in the documentation build. (by Jake Lishman)

Improvements¶

• Add support for Numpy 1.20. QuTiP should be compiled against a version of Numpy >= 1.16.6 and < 1.20 (note: does _not_ include 1.20 itself), but such an installation is compatible with any modern version of Numpy. Source installations from pip understand this constraint.

Improvements¶

• Add support for Scipy 1.5. (by Jake Lishman)

• Improved speed of zcsr_inner, which affects Qobj.overlap. (by Jake Lishman)

• Better error messages when installation requirements are not satisfied. (by Eric Giguère)

Bug Fixes¶

• Fix zcsr_proj acting on matrices with unsorted indices. (by Jake Lishman)

• Fix errors in Milstein’s heterodyne. (by Eric Giguère)

• Fix datatype bug in qutip.lattice module. (by Boxi Li)

• Fix issues with eigh on Mac when using OpenBLAS. (by Eric Giguère)

Developer Changes¶

• Converted more of the codebase to PEP 8.

• Fix several instances of unsafe mutable default values and unsafe is comparisons.

Improvements¶

• husimi and wigner now accept half-integer spin (by maij)

• Better error messages for failed string coefficient compilation. (issue raised by nohchangsuk)

Bug Fixes¶

• Safer naming for temporary files. (by Eric Giguère)

• Fix clebsch function for half-integer (by Thomas Walker)

• Fix randint’s dtype to uint32 for compatibility with Windows. (issue raised by Boxi Li)

• Corrected stochastic’s heterodyne’s m_ops (by eliegenois)

• Mac pool use spawn. (issue raised by goerz)

• Fix typos in QobjEvo._shift. (by Eric Giguère)

• Fix warning on Travis CI. (by Ivan Carvalho)

Deprecations¶

• qutip.graph functions will be deprecated in QuTiP 5.0 in favour of scipy.sparse.csgraph.

Developer Changes¶

• Add Boxi Li to authors. (by Alex Pitchford)

• Skip some tests that cause segfaults on Mac. (by Nathan Shammah and Eric Giguère)

• Use Python 3.8 for testing on Mac and Linux. (by Simon Cross and Eric Giguère)

Improvements¶

• MAJOR FEATURE: Added qip.noise, a module with pulse level description of quantum circuits allowing to model various types of noise and devices (by Boxi Li).

• MAJOR FEATURE: Added qip.lattice, a module for the study of lattice dynamics in 1D (by Saumya Biswas).

• Migrated testing from Nose to PyTest (by Tarun Raheja).

• Optimized testing for PyTest and removed duplicated test runners (by Jake Lishman).

• Deprecated importing qip functions to the qutip namespace (by Boxi Li).

• Added the possibility to define non-square superoperators relevant for quantum circuits (by Arne Grimsmo and Josh Combes).

• Implicit tensor product for qeye, qzero and basis (by Jake Lishman).

• QObjEvo no longer requires Cython for string coefficient (by Eric Giguère).

• Added marked tests for faster tests in testing.run() and made faster OpenMP benchmarking in CI (by Eric Giguère).

• Added entropy and purity for Dicke density matrices, refactored into more general dicke_trace (by Nathan Shammah).

• Added option for specifying resolution in Bloch.save function (by Tarun Raheja).

• Added information related to the value of hbar in wigner and continuous_variables (by Nicolas Quesada).

• Updated requirements for scipy 1.4 (by Eric Giguère).

• Added previous lead developers to the qutip.about() message (by Nathan Shammah).

• Added improvements to Qobj introducing the inv method and making the partial trace, ptrace, faster, keeping both sparse and dense methods (by Eric Giguère).

• Allowed general callable objects to define a time-dependent Hamiltonian (by Eric Giguère).

• Added feature so that QobjEvo no longer requires Cython for string coefficients (by Eric Giguère).

• Updated authors list on Github and added my binder link (by Nathan Shammah).

Bug Fixes¶

• Fixed PolyDataMapper construction for Bloch3d (by Sam Griffiths).

• Fixed error checking for null matrix in essolve (by Nathan Shammah).

• Fixed name collision for parallel propagator (by Nathan Shammah).

• Fixed dimensional incongruence in propagator (by Nathan Shammah)

• Fixed bug by rewriting clebsch function based on long integer fraction (by Eric Giguère).

• Fixed bugs in QobjEvo’s args depending on state and added solver tests using them (by Eric Giguère).

• Fixed bug in sesolve calculation of average states when summing the timeslot states (by Alex Pitchford).

• Fixed bug in steadystate solver by removing separate arguments for MKL and Scipy (by Tarun Raheja).

• Fixed Bloch.add_ponts by setting edgecolor = None in plot_points (by Nathan Shammah).

• Fixed error checking for null matrix in essolve solver affecting also ode2es (by Peter Kirton).

• Removed unnecessary shebangs in .pyx and .pxd files (by Samesh Lakhotia).

• Fixed sesolve and import of os in codegen (by Alex Pitchford).

• Updated plot_fock_distribution by removing the offset value 0.4 in the plot (by Rajiv-B).

Improvements¶

• QobjEvo do not need to start from 0 anymore (by Eric Giguère).

• Add a quantum object purity function (by Nathan Shammah and Shahnawaz Ahmed).

• Add step function interpolation for array time-coefficient (by Boxi Li).

• Generalize expand_oper for arbitrary dimensions, and new method for cyclic permutations of given target cubits (by Boxi Li).

Bug Fixes¶

• Fixed the pickling but that made solver unable to run in parallel on Windows (Thank lrunze for reporting)

• Removed warning when mesolve fall back on sesolve (by Michael Goerz).

• Fixed dimension check and confusing documentation in random ket (by Yariv Yanay).

• Fixed Qobj isherm not working after using Qobj.permute (Thank llorz1207 for reporting).

• Correlation functions call now properly handle multiple time dependant functions (Thank taw181 for reporting).

• Removed mutable default values in mesolve/sesolve (by Michael Goerz).

• Fixed simdiag bug (Thank Croydon-Brixton for reporting).

• Better support of constant QobjEvo (by Boxi Li).

• Fixed potential cyclic import in the control module (by Alexander Pitchford).

Improvements¶

• MAJOR FEATURE: Added methods and techniques to the stochastic solvers (by Eric Giguère) which allows to use a much broader set of solvers and much more efficiently.

• MAJOR FEATURE: Optimization of the montecarlo solver (by Eric Giguère). Computation are faster in many cases. Collapse information available to time dependant information.

• Added the QObjEvo class and methods (by Eric Giguère), which is used behind the scenes by the dynamical solvers, making the code more efficient and tidier. More built-in function available to string coefficients.

• The coefficients can be made from interpolated array with variable timesteps and can obtain state information more easily. Time-dependant collapse operator can have multiple terms.

• New wigner_transform and plot_wigner_sphere function. (by Nithin Ramu).

• ptrace is faster and work on bigger systems, from 15 Qbits to 30 Qbits.

• QIP module: added the possibility for user-defined gates, added the possibility to remove or add gates in any point of an already built circuit, added the molmer_sorensen gate, and fixed some bugs (by Boxi Li).

• Added the quantum Hellinger distance to qutip.metrics (by Wojciech Rzadkowski).

• Implemented possibility of choosing a random seed (by Marek Marekyggdrasil).

• Added a code of conduct to Github.

Bug Fixes¶

• Fixed bug that made QuTiP incompatible with SciPy 1.3.

Improvements¶

• MAJOR FEATURE: Added the Permutational Invariant Quantum Solver (PIQS) module (by Nathan Shammah and Shahnawaz Ahmed) which allows the simluation of large TLSs ensembles including collective and local Lindblad dissipation. Applications range from superradiance to spin squeezing.

• MAJOR FEATURE: Added a photon scattering module (by Ben Bartlett) which can be used to study scattering in arbitrary driven systems coupled to some configuration of output waveguides.

• Cubic_Spline functions as time-dependent arguments for the collapse operators in mesolve are now allowed.

• Added a faster version of bloch_redfield_tensor, using components from the time-dependent version. About 3x+ faster for secular tensors, and 10x+ faster for non-secular tensors.

• Computing Q.overlap() [inner product] is now ~30x faster.

• Added projector method to Qobj class.

• Added fast projector method, Q.proj().

• Computing matrix elements, Q.matrix_element is now ~10x faster.

• Computing expectation values for ket vectors using expect is now ~10x faster.

• Q.tr() is now faster for small Hilbert space dimensions.

• Unitary operator evolution added to sesolve

• Use OPENMP for tidyup if installed.

Bug Fixes¶

• Fixed bug that stopped simdiag working for python 3.

• Fixed semidefinite cvxpy Variable and Parameter.

• Fixed iterative lu solve atol keyword issue.

• Fixed unitary op evolution rhs matrix in ssesolve.

• Fixed interpolating function to return zero outside range.

• Fixed dnorm complex casting bug.

• Fixed control.io path checking issue.

• Fixed ENR fock dimension.

• Fixed hard coded options in propagator ‘batch’ mode

• Fixed bug in trace-norm for non-Hermitian operators.

• Fixed bug related to args not being passed to coherence_function_g2

• Fixed MKL error checking dict key error

Improvements¶

• MAJOR FEATURE: Initial implementation of time-dependent Bloch-Redfield Solver.

• Qobj tidyup is now an order of magnitude faster.

• Time-dependent codegen now generates output NumPy arrays faster.

• Improved calculation for analytic coefficients in coherent states (Sebastian Kramer).

• Input array to correlation FFT method now checked for validity.

• Function-based time-dependent mesolve and sesolve routines now faster.

• Codegen now makes sure that division is done in C, as opposed to Python.

• Can now set different controls for a each timeslot in quantum optimization. This allows time-varying controls to be used in pulse optimisation.

Bug Fixes¶

• rcsolve importing old Odeoptions Class rather than Options.

• Non-int issue in spin Q and Wigner functions.

• Qobj’s should tidyup before determining isherm.

• Fixed time-dependent RHS function loading on Win.

• Fixed several issues with compiling with Cython 0.26.

• Liouvillian superoperators were hard setting isherm=True by default.

• Fixed an issue with the solver safety checks when inputing a list with Python functions as time-dependence.

• Fixed non-int issue in Wigner_cmap.

• MKL solver error handling not working properly.

Improvements¶

Core libraries

• MAJOR FEATURE: QuTiP now works for Python 3.5+ on Windows using Visual Studio 2015.

• MAJOR FEATURE: Cython and other low level code switched to C++ for MS Windows compatibility.

• MAJOR FEATURE: Can now use interpolating cubic splines as time-dependent coefficients.

• MAJOR FEATURE: Sparse matrix - vector multiplication now parallel using OPENMP.

• Automatic tuning of OPENMP threading threshold.

• Partial trace function is now up to 100x+ faster.

• Hermitian verification now up to 100x+ faster.

• Internal Qobj objects now created up to 60x faster.

• Inplace conversion from COO -> CSR sparse formats (e.g. Memory efficiency improvement.)

• Faster reverse Cuthill-Mckee and sparse one and inf norms.

Bug Fixes¶

• Cleanup of temp. Cython files now more robust and working under Windows.

Bug Fixes¶

• td files no longer left behind by correlation tests

• Various fast sparse fixes

Improvements¶

Core libraries

• MAJOR FEATURE: Fast sparse: New subclass of csr_matrix added that overrides commonly used methods to avoid certain checks that incurr execution cost. All Qobj.data now fast_csr_matrix

• HEOM performance enhancements

• spmv now faster

• mcsolve codegen further optimised

Control modules

• Time dependent drift (through list of pwc dynamics generators)

• memory optimisation options provided for control.dynamics

Bug Fixes¶

• recompilation of pyx files on first import removed

• tau array in control.pulseoptim funcs now works

New Features¶

Core libraries

• MAJOR FEATURE: Non-Markovian solvers: Hierarchy (Added by Neill Lambert), Memory-Cascade, and Transfer-Tensor methods.

• MAJOR FEATURE: Default steady state solver now up to 100x faster using the Intel Pardiso library under the Anaconda and Intel Python distributions.

• The default Wigner function now uses a Clenshaw summation algorithm to evaluate a polynomial series that is applicable for any number of exciations (previous limitation was ~50 quanta), and is ~3x faster than before. (Added by Denis Vasilyev)

• Can now define a given eigen spectrum for random Hermitian and density operators.

• The Qobj expm method now uses the equivilent SciPy routine, and performs a much faster exp operation if the matrix is diagonal.

• One can now build zero operators using the qzero function.

Control modules

• MAJOR FEATURE: CRAB algorithm added This is an alternative to the GRAPE algorithm, which allows for analytical control functions, which means that experimental constraints can more easily be added into optimisation. See tutorial notebook for full information.

Improvements¶

Core libraries

• Two-time correlation functions can now be calculated for fully time-dependent Hamiltonians and collapse operators. (Added by Kevin Fischer)

• The code for the inverse-power method for the steady state solver has been simplified.

• Bloch-Redfield tensor creation is now up to an order of magnitude faster. (Added by Johannes Feist)

• Q.transform now works properly for arrays directly from sp_eigs (or eig).

• Q.groundstate now checks for degeneracy.

• Added sinm and cosm methods to the Qobj class.

• Added charge and tunneling operators.

• Time-dependent Cython code is now easier to read and debug.

Control modules

• The internal state / quantum operator data type can now be either Qobj or ndarray Previous only ndarray was possible. This now opens up possibility of using Qobj methods in fidelity calculations The attributes and functions that return these operators are now preceded by an underscore, to indicate that the data type could change depending on the configuration options. In most cases these functions were for internal processing only anyway, and should have been ‘private’. Accessors to the properties that could be useful outside of the library have been added. These always return Qobj. If the internal operator data type is not Qobj, then there could be signicant overhead in the conversion, and so this should be avoided during pulse optimisation. If custom sub-classes are developed that use Qobj properties and methods (e.g. partial trace), then it is very likely that it will be more efficient to set the internal data type to Qobj. The internal operator data will be chosen automatically based on the size and sparsity of the dynamics generator. It can be forced by setting dynamics.oper_dtype = <type> Note this can be done by passing dyn_params={'oper_dtype':<type>} in any of the pulseoptim functions.

  Some other properties and methods were renamed at the same time. A full list is given here.

  • All modules - function: set_log_level -> property: log_level

  • dynamics functions

    • _init_lists now _init_evo

    • get_num_ctrls now property: num_ctrls

    • get_owd_evo_target now property: onto_evo_target

    • combine_dyn_gen now _combine_dyn_gen (no longer returns a value)

    • get_dyn_gen now _get_phased_dyn_gen

    • get_ctrl_den_gen now _get_phased_ctrl_dyn_gen

    • ensure_decomp_curr now _ensure_decomp_curr

    • spectral_decomp now _spectral_decomp

  • dynamics properties

    • evo_init2t now _fwd_evo (fwd_evo as Qobj)

    • evo_t2end now _onwd_evo (onwd_evo as Qobj)

    • evo_t2targ now _onto_evo (onto_evo as Qobj)

  • fidcomp properties

    • uses_evo_t2end now uses_onwd_evo

    • uses_evo_t2targ now uses_onto_evo

    • set_phase_option function now property phase_option

  • propcomp properties

    • grad_exact (now read only)

  • propcomp functions

    • compute_propagator now _compute_propagator

    • compute_diff_prop now _compute_diff_prop

    • compute_prop_grad now _compute_prop_grad

  • tslotcomp functions

    • get_timeslot_for_fidelity_calc now _get_timeslot_for_fidelity_calc

Miscellaneous

• QuTiP Travis CI tests now use the Anaconda distribution.

• The about box and ipynb version_table now display addition system information.

• Updated Cython cleanup to remove depreciation warning in sysconfig.

• Updated ipynb_parallel to look for ipyparallel module in V4 of the notebooks.

Bug Fixes¶

• Fixes for countstat and psuedo-inverse functions

• Fixed Qobj division tests on 32-bit systems.

• Removed extra call to Python in time-dependent Cython code.

• Fixed issue with repeated Bloch sphere saving.

• Fixed T_0 triplet state not normalized properly. (Fixed by Eric Hontz)

• Simplified compiler flags (support for ARM systems).

• Fixed a decoding error in qload.

• Fixed issue using complex.h math and np.kind_t variables.

• Corrected output states mismatch for ntraj=1 in the mcf90 solver.

• Qobj data is now copied by default to avoid a bug in multiplication. (Fixed by Richard Brierley)

• Fixed bug overwriting hardware_info in __init__. (Fixed by Johannes Feist)

• Restored ability to explicity set Q.isherm, Q.type, and Q.superrep.

• Fixed integer depreciation warnings from NumPy.

• Qobj * (dense vec) would result in a recursive loop.

• Fixed args=None -> args={} in correlation functions to be compatible with mesolve.

• Fixed depreciation warnings in mcsolve.

• Fixed neagtive only real parts in rand_ket.

• Fixed a complicated list-cast-map-list antipattern in super operator reps. (Fixed by Stefan Krastanov)

• Fixed incorrect isherm for sigmam spin operator.

• Fixed the dims when using final_state_output in mesolve and sesolve.

New Features¶

• MAJOR FEATURE: New module for quantum control (qutip.control).

• NAMESPACE CHANGE: QuTiP no longer exports symbols from NumPy and matplotlib, so those modules must now be explicitly imported when required.

• New module for counting statistics.

• Stochastic solvers now run trajectories in parallel.

• New superoperator and tensor manipulation functions (super_tensor, composite, tensor_contract).

• New logging module for debugging (qutip.logging).

• New user-available API for parallelization (parallel_map).

• New enhanced (optional) text-based progressbar (qutip.ui.EnhancedTextProgressBar)

• Faster Python based monte carlo solver (mcsolve).

• Support for progress bars in propagator function.

• Time-dependent Cython code now calls complex cmath functions.

• Random numbers seeds can now be reused for successive calls to mcsolve.

• The Bloch-Redfield master equation solver now supports optional Lindblad type collapse operators.

• Improved handling of ODE integration errors in mesolve.

• Improved correlation function module (for example, improved support for time-dependent problems).

• Improved parallelization of mcsolve (can now be interrupted easily, support for IPython.parallel, etc.)

• Many performance improvements, and much internal code restructuring.

Bug Fixes¶

• Cython build files for time-dependent string format now removed automatically.

• Fixed incorrect solution time from inverse-power method steady state solver.

• mcsolve now supports Options(store_states=True)

• Fixed bug in hadamard gate function.

• Fixed compatibility issues with NumPy 1.9.0.

• Progressbar in mcsolve can now be suppressed.

• Fixed bug in gate_expand_3toN.

• Fixed bug for time-dependent problem (list string format) with multiple terms in coefficient to an operator.

Bug Fixes¶

• Fix bug in create(), which returned a Qobj with CSC data instead of CSR.

• Fix several bugs in mcsolve: Incorrect storing of collapse times and collapse operator records. Incorrect averaging of expectation values for different trajectories when using only 1 CPU.

• Fix bug in parsing of time-dependent Hamiltonian/collapse operator arguments that occurred when the args argument is not a dictionary.

• Fix bug in internal _version2int function that cause a failure when parsingthe version number of the Cython package.

New Features¶

• New module qutip.stochastic with stochastic master equation and stochastic Schrödinger equation solvers.

• Expanded steady state solvers. The function steady has been deprecated in favor of steadystate. The steadystate solver no longer use umfpack by default. New pre-processing methods for reordering and balancing the linear equation system used in direct solution of the steady state.

• New module qutip.qip with utilities for quantum information processing, including pre-defined quantum gates along with functions for expanding arbitrary 1, 2, and 3 qubit gates to N qubit registers, circuit representations, library of quantum algorithms, and basic physical models for some common QIP architectures.

• New module qutip.distributions with unified API for working with distribution functions.

• New format for defining time-dependent Hamiltonians and collapse operators, using a pre-calculated numpy array that specifies the values of the Qobj-coefficients for each time step.

• New functions for working with different superoperator representations, including Kraus and Chi representation.

• New functions for visualizing quantum states using Qubism and Schimdt plots: plot_qubism and plot_schmidt.

• Dynamics solver now support taking argument e_ops (expectation value operators) in dictionary form.

• Public plotting functions from the qutip.visualization module are now prefixed with plot_ (e.g., plot_fock_distribution). The plot_wigner and plot_wigner_fock_distribution now supports 3D views in addition to contour views.

• New API and new functions for working with spin operators and states, including for example spin_Jx, spin_Jy, spin_Jz and spin_state, spin_coherent.

• The expect function now supports a list of operators, in addition to the previously supported list of states.

• Simplified creation of qubit states using ket function.

• The module qutip.cyQ has been renamed to qutip.cy and the sparse matrix-vector functions spmv and spmv1d has been combined into one function spmv. New functions for operating directly on the underlaying sparse CSR data have been added (e.g., spmv_csr). Performance improvements. New and improved Cython functions for calculating expectation values for state vectors, density matrices in matrix and vector form.

• The concurrence function now supports both pure and mixed states. Added function for calculating the entangling power of a two-qubit gate.

• Added function for generating (generalized) Lindblad dissipator superoperators.

• New functions for generating Bell states, and singlet and triplet states.

• QuTiP no longer contains the demos GUI. The examples are now available on the QuTiP web site. The qutip.gui module has been renamed to qutip.ui and does no longer contain graphical UI elements. New text-based and HTML-based progressbar classes.

• Support for harmonic oscillator operators/states in a Fock state basis that does not start from zero (e.g., in the range [M,N+1]). Support for eliminating and extracting states from Qobj instances (e.g., removing one state from a two-qubit system to obtain a three-level system).

• Support for time-dependent Hamiltonian and Liouvillian callback functions that depend on the instantaneous state, which for example can be used for solving master equations with mean field terms.

Improvements¶

• Restructured and optimized implementation of Qobj, which now has significantly lower memory footprint due to avoiding excessive copying of internal matrix data.

• The classes OdeData, Odeoptions, Odeconfig are now called Result, Options, and Config, respectively, and are available in the module qutip.solver.

• The squeez function has been renamed to squeeze.

• Better support for sparse matrices when calculating propagators using the propagator function.

• Improved Bloch sphere.

• Restructured and improved the module qutip.sparse, which now only operates directly on sparse matrices (not on Qobj instances).

• Improved and simplified implement of the tensor function.

• Improved performance, major code cleanup (including namespace changes), and numerous bug fixes.

• Benchmark scripts improved and restructured.

• QuTiP is now using continuous integration tests (TravisCI).

New Features¶

• Added Support for Windows

• New Bloch3d class for plotting 3D Bloch spheres using Mayavi.

• Bloch sphere vectors now look like arrows.

• Partial transpose function.

• Continuos variable functions for calculating correlation and covariance matrices, the Wigner covariance matrix and the logarithmic negativity for for multimode fields in Fock basis.

• The master-equation solver (mesolve) now accepts pre-constructed Liouvillian terms, which makes it possible to solve master equations that are not on the standard Lindblad form.

• Optional Fortran Monte Carlo solver (mcsolve_f90) by Arne Grimsmo.

• A module of tools for using QuTiP in IPython notebooks.

• Increased performance of the steady state solver.

• New Wigner colormap for highlighting negative values.

• More graph styles to the visualization module.

Bug Fixes¶

• Function based time-dependent Hamiltonians now keep the correct phase.

• mcsolve no longer prints to the command line if ntraj=1.

New Features¶

• New method for generating Wigner functions based on Laguerre polynomials.

• coherent(), coherent_dm(), and thermal_dm() can now be expressed using analytic values.

• Unittests now use nose and can be run after installation.

• Added iswap and sqrt-iswap gates.

• Functions for quantum process tomography.

• Window icons are now set for Ubuntu application launcher.

• The propagator function can now take a list of times as argument, and returns a list of corresponding propagators.

Bug Fixes¶

• mesolver now correctly uses the user defined rhs_filename in Odeoptions().

• rhs_generate() now handles user defined filenames properly.

• Density matrix returned by propagator_steadystate is now Hermitian.

• eseries_value returns real list if all imag parts are zero.

• mcsolver now gives correct results for strong damping rates.

• Odeoptions now prints mc_avg correctly.

• Do not check for PyObj in mcsolve when gui=False.

• Eseries now correctly handles purely complex rates.

• thermal_dm() function now uses truncated operator method.

• Cython based time-dependence now Python 3 compatible.

• Removed call to NSAutoPool on mac systems.

• Progress bar now displays the correct number of CPU’s used.

• Qobj.diag() returns reals if operator is Hermitian.

• Text for progress bar on Linux systems is no longer cutoff.

New Features¶

• QuTiP now includes solvers for both Floquet and Bloch-Redfield master equations.

• The Lindblad master equation and Monte Carlo solvers allow for time-dependent collapse operators.

• It is possible to automatically compile time-dependent problems into c-code using Cython (if installed).

• Python functions can be used to create arbitrary time-dependent Hamiltonians and collapse operators.

• Solvers now return Odedata objects containing all simulation results and parameters, simplifying the saving of simulation results.

• mesolve and mcsolve can reuse Hamiltonian data when only the initial state, or time-dependent arguments, need to be changed.

• QuTiP includes functions for creating random quantum states and operators.

• The generation and manipulation of quantum objects is now more efficient.

• Quantum objects have basis transformation and matrix element calculations as built-in methods.

• The quantum object eigensolver can use sparse solvers.

• The partial-trace (ptrace) function is up to 20x faster.

• The Bloch sphere can now be used with the Matplotlib animation function, and embedded as a subplot in a figure.

• QuTiP has built-in functions for saving quantum objects and data arrays.

• The steady-state solver has been further optimized for sparse matrices, and can handle much larger system Hamiltonians.

• The steady-state solver can use the iterative bi-conjugate gradient method instead of a direct solver.

• There are three new entropy functions for concurrence, mutual information, and conditional entropy.

• Correlation functions have been combined under a single function.

• The operator norm can now be set to trace, Frobius, one, or max norm.

• Global QuTiP settings can now be modified.

• QuTiP includes a collection of unit tests for verifying the installation.

• Demos window now lets you copy and paste code from each example.

Bug Fixes¶

• Fixed bug pointed out by Brendan Abolins.

• Qobj.tr() returns zero-dim ndarray instead of float or complex.

• Updated factorial import for scipy version 0.10+

New Functions¶

• Allow custom naming of Bloch sphere.

Bug Fixes¶

• Fixed text alignment issues in AboutBox.

• Added fix for SciPy V>0.10 where factorial was moved to scipy.misc module.

• Added tidyup function to tensor function output.

• Removed openmp flags from setup.py as new Mac Xcode compiler does not recognize them.

• Qobj diag method now returns real array if all imaginary parts are zero.

• Examples GUI now links to new documentation.

• Fixed zero-dimensional array output from metrics module.

Bug Fixes¶

• Fixed issue where Monte Carlo states were not output properly.

New Functions¶

• Added linear entropy function.

• Number of CPU’s can now be changed.

Bug Fixes¶

• Metrics no longer use dense matrices.

• Fixed Bloch sphere grid issue with matplotlib 1.1.

• Qobj trace operation uses only sparse matrices.

• Fixed issue where GUI windows do not raise to front.

New Functions¶

• tidyup function to remove small elements from a Qobj.

• Added concurrence function.

• Added simdiag for simultaneous diagonalization of operators.

• Added eigenstates method returning eigenstates and eigenvalues to Qobj class.

• Added fileio for saving and loading data sets and/or Qobj’s.

• Added hinton function for visualizing density matrices.

Bug Fixes¶

• Switched Examples to new Signals method used in PySide 1.0.6+.

• Switched ProgressBar to new Signals method.

• Fixed memory issue in expm functions.

• Fixed memory bug in isherm.

• Made all Qobj data complex by default.

• Reduced ODE tolerance levels in Odeoptions.

• Fixed bug in ptrace where dense matrix was used instead of sparse.

• Fixed issue where PyQt4 version would not be displayed in about box.

• Fixed issue in Wigner where xvec was used twice (in place of yvec).