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Qiskit 0.9 release notes

0.9

Terra 0.8

Highlights

  • Introduction of the Pulse module under qiskit.pulse, which includes tools for building pulse commands, scheduling them on pulse channels, visualization, and running them on IBM Q devices.
  • Improved QuantumCircuit and Instruction classes, allowing for the composition of arbitrary sub-circuits into larger circuits, and also for creating parameterized circuits.
  • A powerful Quantum Info module under qiskit.quantum_info, providing tools to work with operators and channels and to use them inside circuits.
  • New transpiler optimization passes and access to predefined transpiling routines.

New Features

  • The core StochasticSwap routine is implemented in Cython.
  • Added QuantumChannel classes for manipulating quantum channels and CPTP maps.
  • Support for parameterized circuits.
  • The PassManager interface has been improved and new functions added for easier interaction and usage with custom pass managers.
  • Preset PassManagers are now included which offer a predetermined pipeline of transpiler passes.
  • User configuration files to let local environments override default values for some functions.
  • New transpiler passes: EnlargeWithAncilla, Unroll2Q, NoiseAdaptiveLayout, OptimizeSwapBeforeMeasure, RemoveDiagonalGatesBeforeMeasure, CommutativeCancellation, Collect2qBlocks, and ConsolidateBlocks.

Compatibility Considerations

As part of the 0.8 release the following things have been deprecated and will either be removed or changed in a backwards incompatible manner in a future release. While not strictly necessary these are things to adjust for before the 0.9 (unless otherwise noted) release to avoid a breaking change in the future.

  • The methods prefixed by _get in the DAGCircuit object are being renamed without that prefix.
  • Changed elements in couplinglist of CouplingMap from tuples to lists.
  • Unroller bases must now be explicit, and violation raises an informative QiskitError.
  • The qiskit.tools.qcvv package is deprecated and will be removed in the in the future. You should migrate to using the Qiskit Ignis which replaces this module.
  • The qiskit.compile() function is now deprecated in favor of explicitly using the qiskit.compiler.transpile() function to transform a circuit, followed by qiskit.compiler.assemble() to make a Qobj out of it. Instead of compile(...), use assemble(transpile(...), ...).
  • qiskit.converters.qobj_to_circuits() has been deprecated and will be removed in a future release. Instead qiskit.assembler.disassemble() should be used to extract QuantumCircuit objects from a compiled Qobj.
  • The qiskit.mapper namespace has been deprecated. The Layout and CouplingMap classes can be accessed via qiskit.transpiler.
  • A few functions in qiskit.tools.qi.qi have been deprecated and moved to qiskit.quantum_info.

Please note that some backwards incompatible changes have been made during this release. The following notes contain information on how to adapt to these changes.

IBM Q Provider

The IBM Q provider was previously included in Terra, but it has been split out into a separate package qiskit-ibmq-provider. This will need to be installed, either via pypi with pip install qiskit-ibmq-provider or from source in order to access qiskit.IBMQ or qiskit.providers.ibmq. If you install qiskit with pip install qiskit, that will automatically install all subpackages of the Qiskit project.

Cython Components

Starting in the 0.8 release the core stochastic swap routine is now implemented in Cython. This was done to significantly improve the performance of the swapper, however if you build Terra from source or run on a non-x86 or other platform without prebuilt wheels and install from source distribution you’ll need to make sure that you have Cython installed prior to installing/building Qiskit Terra. This can easily be done with pip/pypi: pip install Cython.

Compiler Workflow

The qiskit.compile() function has been deprecated and replaced by first calling qiskit.compiler.transpile() to run optimization and mapping on a circuit, and then qiskit.compiler.assemble() to build a Qobj from that optimized circuit to send to a backend. While this is only a deprecation it will emit a warning if you use the old qiskit.compile() call.

transpile(), assemble(), execute() parameters

These functions are heavily overloaded and accept a wide range of inputs. They can handle circuit and pulse inputs. All kwargs except for backend for these functions now also accept lists of the previously accepted types. The initial_layout kwarg can now be supplied as a both a list and dictionary, e.g. to map a Bell experiment on qubits 13 and 14, you can supply: initial_layout=[13, 14] or initial_layout={qr[0]: 13, qr[1]: 14}

Qobj

The Qobj class has been split into two separate subclasses depending on the use case, either PulseQobj or QasmQobj for pulse and circuit jobs respectively. If you’re interacting with Qobj directly you may need to adjust your usage accordingly.

The qiskit.qobj.qobj_to_dict() is removed. Instead use the to_dict() method of a Qobj object.

Visualization

The largest change to the visualization module is it has moved from qiskit.tools.visualization to qiskit.visualization. This was done to indicate that the visualization module is more than just a tool. However, since this interface was declared stable in the 0.7 release the public interface off of qiskit.tools.visualization will continue to work. That may change in a future release, but it will be deprecated prior to removal if that happens.

The previously deprecated functions, plot_circuit(), latex_circuit_drawer(), generate_latex_source(), and matplotlib_circuit_drawer() from qiskit.tools.visualization have been removed. Instead of these functions, calling qiskit.visualization.circuit_drawer() with the appropriate arguments should be used.

The previously deprecated plot_barriers and reverse_bits keys in the style kwarg dictionary are deprecated, instead the qiskit.visualization.circuit_drawer() kwargs plot_barriers and reverse_bits should be used.

The Wigner plotting functions plot_wigner_function, plot_wigner_curve, plot_wigner_plaquette, and plot_wigner_data previously in the qiskit.tools.visualization._state_visualization module have been removed. They were never exposed through the public stable interface and were not well documented. The code to use this feature can still be accessed through the qiskit-tutorials repository.

Mapper

The public api from qiskit.mapper has been moved into qiskit.transpiler. While it has only been deprecated in this release, it will be removed in the 0.9 release so updating your usage of Layout and CouplingMap to import from qiskit.transpiler instead of qiskit.mapper before that takes place will avoid any surprises in the future.

Aer 0.2

New Features

Bug Fixes

  • Fixed OpenMP clashing problems on macOS for the Terra add-on qiskit-aer #46

Compatibility Considerations

  • Deprecated "initial_statevector" backend option for QasmSimulator and StatevectorSimulator qiskit-aer #185
  • Renamed "chop_threshold" backend option to "zero_threshold" and changed default value to 1e-10 qiskit-aer #185

Ignis 0.1

New Features

  • Quantum volume
  • Measurement mitigation using tensored calibrations
  • Simultaneous RB has the option to align Clifford gates across subsets
  • Measurement correction can produce a new calibration for a subset of qubits

Compatibility Considerations

  • RB writes to the minimal set of classical registers (it used to be Q[i]->C[i]). This change enables measurement correction with RB. Unless users had external analysis code, this will not change outcomes. RB circuits from 0.1 are not compatible with 0.1.1 fitters.

Aqua 0.5

New Features

  • Implementation of the HHL algorithm supporting LinearSystemInput
  • Pluggable component Eigenvalues with variant EigQPE
  • Pluggable component Reciprocal with variants LookupRotation and LongDivision
  • Multiple-Controlled U1 and U3 operations mcu1 and mcu3
  • Pluggable component QFT derived from component IQFT
  • Summarized the transpiled circuits at the DEBUG logging level
  • QuantumInstance accepts basis_gates and coupling_map again.
  • Support to use cx gate for the entanglement in RY and RYRZ variational form (cz is the default choice)
  • Support to use arbitrary mixer Hamiltonian in QAOA, allowing use of QAOA in constrained optimization problems [arXiv:1709.03489]
  • Added variational algorithm base class VQAlgorithm, implemented by VQE and QSVMVariational
  • Added ising/docplex.py for automatically generating Ising Hamiltonian from optimization models of DOcplex
  • Added 'basic-dirty-ancilla’ mode for mct
  • Added mcmt for Multi-Controlled, Multi-Target gate
  • Exposed capabilities to generate circuits from logical AND, OR, DNF (disjunctive normal forms), and CNF (conjunctive normal forms) formulae
  • Added the capability to generate circuits from ESOP (exclusive sum of products) formulae with optional optimization based on Quine-McCluskey and ExactCover
  • Added LogicalExpressionOracle for generating oracle circuits from arbitrary Boolean logic expressions (including DIMACS support) with optional optimization capability
  • Added TruthTableOracle for generating oracle circuits from truth-tables with optional optimization capability
  • Added CustomCircuitOracle for generating oracle from user specified circuits
  • Added implementation of the Deutsch-Jozsa algorithm
  • Added implementation of the Bernstein-Vazirani algorithm
  • Added implementation of the Simon’s algorithm
  • Added implementation of the Shor’s algorithm
  • Added optional capability for Grover’s algorithm to take a custom initial state (as opposed to the default uniform superposition)
  • Added capability to create a Custom initial state using existing circuit
  • Added the ADAM (and AMSGRAD) optimization algorithm
  • Multivariate distributions added, so uncertainty models now have univariate and multivariate distribution components
  • Added option to include or skip the swaps operations for qft and iqft circuit constructions
  • Added classical linear system solver ExactLSsolver
  • Added parameters auto_hermitian and auto_resize to HHL algorithm to support non-Hermitian and non 2n2^n sized matrices by default
  • Added another feature map, RawFeatureVector, that directly maps feature vectors to qubits’ states for classification
  • SVM_Classical can now load models trained by QSVM

Bug Fixes

  • Fixed ising/docplex.py to correctly multiply constant values in constraints
  • Fixed package setup to correctly identify namespace packages using setuptools.find_namespace_packages

Compatibility Considerations

  • QuantumInstance does not take memory anymore.
  • Moved command line and GUI to separate repo (qiskit_aqua_uis)
  • Removed the SAT-specific oracle (now supported by LogicalExpressionOracle)
  • Changed advanced mode implementation of mct: using simple h gates instead of ch, and fixing the old recursion step in _multicx
  • Components random_distributions renamed to uncertainty_models
  • Reorganized the constructions of various common gates (ch, cry, mcry, mct, mcu1, mcu3, mcmt, logic_and, and logic_or) and circuits (PhaseEstimationCircuit, BooleanLogicCircuits, FourierTransformCircuits, and StateVectorCircuits) under the circuits directory
  • Renamed the algorithm QSVMVariational to VQC, which stands for Variational Quantum Classifier
  • Renamed the algorithm QSVMKernel to QSVM
  • Renamed the class SVMInput to ClassificationInput
  • Renamed problem type 'svm_classification' to 'classification'
  • Changed the type of entangler_map used in FeatureMap and VariationalForm to list of lists

IBM Q Provider 0.1

New Features

  • This is the first release as a standalone package. If you are installing Terra standalone you’ll also need to install the qiskit-ibmq-provider package with pip install qiskit-ibmq-provider if you want to use the IBM Q backends.
  • Support for non-Qobj format jobs has been removed from the provider. You’ll have to convert submissions in an older format to Qobj before you can submit.
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