Skip to content

pyQuil 2.3
Compare
Choose a tag to compare
@mpharrigan mpharrigan released this 28 Jan 19:30
· 657 commits to master since this release
v2.3.0
e3fb8a7

PyQuil 2.3 is the latest release of pyQuil, Rigetti's toolkit for constructing and running
quantum programs. A major new feature is the release of a new suite of simulators:

  • We're proud to introduce the first iteration of a Python-based quantum virtual machine (QVM) called PyQVM. This QVM is completely contained within pyQuil and does not need any external dependencies. Try using it with get_qc("9q-square-pyqvm") or explore the pyquil.pyqvm.PyQVM object directly. Under-the-hood, there are three quantum simulator backends:

    • ReferenceWavefunctionSimulator uses standard matrix-vector multiplication to evolve a statevector. This includes a suite of tools in pyquil.unitary_tools for dealing with unitary matrices.
    • NumpyWavefunctionSimulator uses numpy's tensordot functionality to efficiently evolve a statevector. For most simulations, performance is quite good.
    • ReferenceDensitySimulator uses matrix-matrix multiplication to evolve a density matrix.

  • Matrix representations of Quil standard gates are included in pyquil.gate_matrices (gh-552).

  • The density simulator has extremely limited support for Kraus-operator based noise models. Let us know if you're interested in contributing more robust noise-model support.

  • This functionality should be considered experimental and may undergo minor API changes.

Important changes to note:

  • Quil math functions (like COS, SIN, ...) used to be ambiguous with respect to case sensitivity. They are now case-sensitive and should be uppercase (gh-774).
  • In the next release of pyQuil, communication with quilc will happen exclusively via the rpcq protocol. LocalQVMCompiler and LocalBenchmarkConnection will be removed in favor of a unified QVMCompiler and BenchmarkConnection. This change should be transparent if you use get_qc and get_benchmarker, respectively. In anticipation of this change we recommend that you upgrade your version of quilc to 1.3, released Jan 30, 2019 (gh-730).
  • When using a paramaterized gate, the QPU control electronics only allowed multiplying parameters by powers of two. If you only ever multiply a parameter by the same constant, this isn't too much of a problem because you can fold the multiplicative constant into the definition of the parameter. However, if you are multiplying the same variable (e.g. gamma in QAOA) by different constants (e.g. weighted maxcut edge weights) it doesn't work. PyQuil will now transparently handle the latter case by expanding to a vector of parameters with the constants folded in, allowing you to multiply variables by whatever you want (gh-707).

As always, this release contains bug fixes and improvements:

  • The CZ gate fidelity metric available in the Specs object now has its associated standard error, which is accessible from the method Specs.fCZ_std_errs (gh-751).
  • Operator estimation code now correctly handles identity terms with coefficients. Previously, it would always estimate these terms as 1.0 (gh-758).
  • Operator estimation results include the total number of counts (shots) taken.
  • Operator estimation JSON serialization uses utf-8. Please let us know if this causes problems (gh-769).
  • The example quantum die program now can roll dice that are not powers of two (gh-749).
  • The teleportation and Meyer penny game examples had a syntax error (gh-778, gh-772).
  • When running on the QPU, you could get into trouble if the QPU name passed to get_qc did not match the lattice you booked. This is now validated (gh-771).

We extend thanks to community member estamm12 for their contribution to this release.

Assets 2
Loading