Release 0.23.0

New features

• Program Xanadu’s new Borealis hardware device via Strawberry Fields and Xanadu Cloud. (#714)

  Borealis is a cloud-accessible photonic quantum computer, offering full programmability over all of its gates and capable of quantum advantage. Its hardware is based on time-domain multiplexing (TDM); a single squeezed-light source emits batches of 216 time-ordered squeezed-light pulses that interfere with one another with the help of optical delay loops, programmable beamsplitters, and phase shifters.

  Learn more about Borealis via our website and tutorials.

• GBS data visualization functions are added. (#714)

• A set of TDM compilers are added, including a Borealis compiler which compiles and validates programs against the hardware specification and calibration certificate. (#714)

• A remove_loss utility function is added to the program_utils module, allowing for the removal of LossChannels from Strawberry Fields programs. (#714)

• Cropping vacuum modes from TDM program results is now possible by passing crop=True as a run option. (#714)

  n, N = get_mode_indices(delays)
  prog = sf.TDMProgram(N)
  
  with prog.context(*gate_args) as (p, q):
      ops.Sgate(p[0]) | q[n[0]]
      for i in range(len(delays)):
          ops.Rgate(p[2 * i + 1]) | q[n[i]]
          ops.BSgate(p[2 * i + 2], np.pi / 2) | (q[n[i + 1]], q[n[i]])
      ops.MeasureX | q[0]
  
  eng = sf.Engine("gaussian")
  results = eng.run(prog, crop=True)

• Resulting samples from TDM jobs return only the non-empty mode measurements when setting the crop option to True in the program run_options or as a keyword argument in the engine run method. (#714)

• Realistic loss can be added to a Borealis circuit for local simulation execution. (#714)

  compile_options = {
      "device": device,  # hardware device object needed
      "realistic_loss": True,
  }
  
  eng = sf.Engine("gaussian")
  results = eng.run(prog, compile_options=compile_options)

• Utility functions are added to allow for easier Borealis program and parameter creation. (#714)

• Functions are added for analyzing GBS results for comparisons with classical simulations. (#714)

Improvements

• A locked program can now be (un)rolled, and automatically restores the lock if previously in place. (#703)

• Rolling and unrolling now only happens in place, and no longer returns the (un)rolled circuit. (#702)

• Program.assert_number_of_modes and Program.assert_max_number_of_measurements are combined into a single assert_modes method. (#709)

• Job results can now be retrieved without converting integers to np.int64 objects by setting integer_overflow_protection=False (default True) when running a program via RemoteEngine.run(). (#712)

• The TDM module is refactored to contain program.py, with the TDMProgram class, and utils.py, with various utility functions. (#714)

• The Compiler base class is updated to allow for setting a rigid circuit layout to validate a program during compilation. (#714)

• The Compiler base class now contains methods that can be overwritten to provide subclass compilers with loss-additions (e.g., to add realistic loss to a circuit) and program parameter updates. (#714)

Bug fixes

• Trying to unroll an already unrolled program with a different number of shots works as expected. (#702)

• Fixed bug with vacuum modes missing. (#702)

• Validating parameters now works with nested parameter arrays. (#711)

• Store correct rolled circuit before unrolling (fixes issue when rolled circuit has changed due to e.g., compilation). (#710)

Documentation

• The centralized Xanadu Sphinx Theme is now used to style the Sphinx documentation. (#701)

• The documentation on Gaussian circuit operations is fixed so that it's properly rendered. (#714)

Contributors

This release contains contributions from (in alphabetical order):

Mikhail Andrenkov, Sebastian Duque, Luke Helt, Theodor Isacsson, Josh Izaac, Fabian Laudenbach