ProjectQ v0.4.1

New Features

• New tutorial implementing parts of the following paper (showcasing how to use the new gates of this release):
  Quantum Algorithm for Spectral Measurement with Lower Gate Count
  by David Poulin, Alexei Kitaev, Damian S. Steiger, Matthew B. Hastings, Matthias Troyer
  Phys. Rev. Lett. 121, 010501 (2018)
  (arXiv:1711.11025)

• QubitOperator can now be used as a gate if it contains only one term and is unitary:

QubitOperator("X1 Z2", -1j) | qureg

• New gate for general state preparation, see StatePreparation

• New Uniformly controlled rotations (Ry and Rz), see UniformlyControlledRy and UniformlyControlledRz

• Decomposition for SqrtSwap

Improvements

• Optimized decomposition of multi-controlled X
• BasicGate == tests now for matrix property which enables the following fast option to create a gate defined by a matrix:

gate = BasicGate()
gate.matrix = np.matrix(...)

(It is still suggested to create a new gate class by deriving from BasicGate if the gate is used frequently or to use the symbolic gate decompositions of ProjectQ)

• Allow string input for collapse_wavefunction method of the Simulator

Fixes

• Running circuits on IBM now also works if the circuit is trivial, i.e., it contains no gates but only measurements.

ProjectQ v0.4

New Features

• Mappers: Implementation of a BasicMapper class supported by all backends.
• Mappers: 1D and 2D grid mappers, see our new mapper tutorial.
• Interface to RevKit (big thanks @msoeken). Examples can be found here and here.
• Automatic mapping for the IBM 16 qubit chip, see the new IBMQ tutorial.
• Updated the IBMBackend to allow to retrieve timed-out jobs, see the new IBMQ tutorial.
• New setups for compiling to a restricted gate set with a) all-to-all connectivity (see projectq.setups.restrictedgateset) b) linear chain of qubits (see projectq.setups.linear) c) a 2D grid of qubits (see projectq.setups.grid).
• Improved Error Handling: No multiple errors anymore, error messages are simplified (full error message still available if one sets verbose=True in the MainEngine).
• Support for CZ gate.
• New option for the CircuitDrawer to make all qubit lines start at the beginning.

Improvements:

• Speed improvement of the LocalOptimizer
• Increase seed range of the Simulator

Breaking Changes

• Setups are now explicit. Previously one could import projectq.setups.ibm which automatically changed the engine_list in the MainEngine. This does not work anymore! Instead it now has to be done explicitly: MainEngine(engine_list=projectq.setups.ibm.get_engine_list()). This change was necessary to allow more advanced setups with different options, see the updated compiler tutorial.
• Measure gate is now strictly a single qubit gate. Previously it was possible to apply a Measure gate to a quantum register. Now one has to write All(Measure) | qureg (from projectq.ops import All, Measure). Previous codes still run with Measure | qureg but it will give a warning and support for this syntax will end with the next release.

ProjectQ v0.3.6

New Features

• Basic support for 16-qubit IBM chip added (mapping needs to be done manually still)
• Added support for barriers and arbitrary rotation gates for the IBM backend
• New decomposition rules for conversion of rotation gates
• New gates: sqrt(X) and sqrt(Swap)
• Resource counter keeps track of gate objects (and not just their string representation)

Fixes

• Simulator throws exception if number of qubits does not agree with the gate size being applied (easier to find bugs in user code)
• Classical simulator now registers measurement results like every other backend, allowing to use int(qubit) after measurement
• Fixed bug in emulation of controlled time evolution gates
• Fixed Python 3.6 incompatibility of decomposition rules

ProjectQ v0.3.5

New Features

• The user can now select which of the 5-qubit IBM QE chips to use (ibmqx2 or ibmqx4). See https://github.com/ProjectQ-Framework/ProjectQ/blob/develop/examples/ibm.py for an example.

ProjectQ v0.3.4

New Features

• Compilation to 1- and 2-qubit gates using Barenco et al.'s decompositions.
• Example of compiling to a specific gate set, see https://github.com/ProjectQ-Framework/ProjectQ/blob/develop/examples/compiler_tutorial.ipynb
• Simulator can execute general QubitOperators directly; even non-unitary gates are possible.
• ProjectQ allows user-defined k-qubit gates for k <= 5, and the simulator can execute them directly.

ProjectQ v0.3.3

Changes

• Workaround for issue with pybind11 version 2.2.0
• set_wavefunction of the python simulator now also accepts purely real wavefunctions (using float instead of complex type)

ProjectQ v0.3.2

New features & changes

New simulator feature

Simulator.collapse_wavefunction allows to collapse the wavefunction according to a user-specified outcome. See http://projectq.readthedocs.io/en/latest/projectq.backends.html#projectq.backends.Simulator.collapse_wavefunction for details.

New tutorial

New simulator tutorial added to the examples folder (https://github.com/ProjectQ-Framework/ProjectQ/tree/develop/examples). It explains all basic & more advanced features of the simulator.

Check it out: https://github.com/ProjectQ-Framework/ProjectQ/blob/develop/examples/simulator_tutorial.ipynb

Easier installation on MacOS

MacOS installation now supports default XCode compiler.
See http://projectq.readthedocs.io/en/latest/tutorials.html#detailed-instructions-and-os-specific-hints for details.

Test coverage

... is now at 100% (after rounding :-) )

ProjectQ v0.3.1

New simulator features:

• get_probability/amplitude functions for easier access (compared to cheat)
• set_wavefunction to initialize the simulator to an arbitrary wavefunction

see http://projectq.readthedocs.io/en/latest/projectq.backends.html#projectq.backends.Simulator

ProjectQ v0.3.0

New

• Time evolution gate to evolve under a Hamiltonian (QubitOperator)
• Expectation value feature added to simulator

ProjectQ v0.2.0

New

• New mapper for the IBM Quantum Experience chip which extends the possible options for applying a CNOT gate by taking into account the new hardware restrictions of the current chip. The interface is changed to support QASM 2.0.

Changes

• Changed code style guidelines to indentation using 4 spaces and updated all the code.

Breaking Changes

• Decompositions rules are not global anymore which makes testing a lot easier. Compared to the previous version, the initializer of the AutoReplacer now requires a decomposition rule set as an input parameter.