StrawberryFields 0.17.0

Release 0.17.0

on Python PyPI

New features since last release

• TDMProgram objects can now be compiled and submitted via the API. (#476)

• Wigner functions can be plotted directly via Strawberry Fields using Plot.ly. (#495)

  prog = sf.Program(1)
  eng = sf.Engine('fock', backend_options={"cutoff_dim": 10})
  
  with prog.context as q:
      gamma = 2
      Vgate(gamma) | q[0]
  
  state = eng.run(prog).state
  
  xvec = np.arange(-4, 4, 0.01)
  pvec = np.arange(-4, 4, 0.01)
  mode = 0
  
  sf.plot_wigner(state, mode, xvec, pvec, renderer="browser")

• Fock state marginal probabilities can be plotted directly via Strawberry Fields using Plot.ly. (#510)

  prog = sf.Program(1)
  eng = sf.Engine('fock', backend_options={"cutoff_dim":5})
  
  with prog.context as q:
      Sgate(0.5) | q[0]
  
  state = eng.run(prog).state
  state.all_fock_probs()
  
  modes = [0]
  
  sf.plot_fock(state, modes, cutoff=5, renderer="browser")

• Position and momentum quadrature probabilities can be plotted directly via Strawberry Fields using Plot.ly. (#510)

  prog = sf.Program(1)
  eng = sf.Engine('fock', backend_options={"cutoff_dim":5})
  
  with prog.context as q:
      Sgate(0.5) | q[0]
  
  state = eng.run(prog).state
  
  modes = [0]
  xvec = np.arange(-4, 4, 0.1)
  pvec = np.arange(-4, 4, 0.1)
  
  sf.plot_quad(state, modes, xvec, pvec, renderer="browser")

• Strawberry Fields code can be generated from a program (and an engine) by calling sf.io.generate_code(program, eng=engine). (#496)

Improvements

• Connection objects now send versioned requests to the platform API. (#512)

• TDMProgram allows application of gates with more than one symbolic parameter. #492

• The copies option, when constructing a TDMProgram, has been removed. Instead, the number of copies of a TDM algorithm can now be set by passing the shots keyword argument to the eng.run() method. (#489)

  >>> with prog.context([1, 2], [3, 4]) as (p, q):
  ...     ops.Sgate(0.7, 0) | q[1]
  ...     ops.BSgate(p[0]) | (q[0], q[1])
  ...     ops.MeasureHomodyne(p[1]) | q[0]
  >>> eng = sf.Engine("gaussian")
  >>> results = eng.run(prog, shots=3)

  Furthermore, the TDMProgram.unrolled_circuit attribute now only contains the single-shot unrolled circuit. Unrolling with multiple shots can still be specified via the unroll method: TDMProgram.unroll(shots=60).

• The Result.samples returned by TDM programs has been updated to return samples of shape (shots, spatial modes, timebins) instead of (shots, spatial modes * timebins). (#489)

• A sample post-processing function is added that allows users to move vacuum mode measurements from the first shots to the last shots, and potentially crop out the final shots containing these measurements. (#489)

• pytest-randomly is added to the SF tests. (#480)

• TDMProgram objects can now be serialized into Blackbird scripts, and vice versa. (#476)

Breaking Changes

• Jobs are submitted to the Xanadu Quantum Cloud through a new OAuth based authentication flow using offline refresh tokens and access tokens. (#520)

Bug fixes

• Fixes a bug where Dgate, Coherent, and DisplacedSqueezed do not support TensorFlow tensors if the tensor has an added dimension due to the existence of batching. (#507)

• Fixes an issue with reshape_samples where the samples were sometimes reshaped in the wrong way. (#489)

• The list of modes is now correctly added to the Blackbird program when using the io.to_blackbird function. (#476)

• Fixes a bug where printing the Result object containing samples from a time-domain job would result in an error. Printing the result object now correctly displays information about the results. (#493)

• Removes the antlr4 requirement due to version conflicts. (#494)

• TDMProgram.run_options is now correctly used when running a TDM program. (#500)

• Fixes a bug where a single parameter list passed to the TDMProgram context results in an error. (#503)

Documentation

• TDMProgram docstring is updated to make it clear that only Gaussian programs are allowed. (#519)

• Clarifies special cases for the MZgate in the docstring. (#479)

Contributors

This release contains contributions from (in alphabetical order):

Tom Bromley, Jack Brown, Theodor Isacsson, Josh Izaac, Fabian Laudenbach, Tim Leisti, Nicolas Quesada, Antal Száva.