Release 0.8.1

New features

• The catalyst.mitigate_with_zne error mitigation compilation pass now supports the option to fold gates locally as well as the existing method of globally. (#1006) (#1129)

  While global folding applies the scale factor by forming the inverse of the entire quantum circuit (without measurements) and repeating the circuit with its inverse, local folding instead inserts per-gate folding sequences directly in place of each gate in the original circuit.

  For example,

  import jax
  import pennylane as qml
  from catalyst import qjit, mitigate_with_zne
  from pennylane.transforms import exponential_extrapolate
  
  dev = qml.device("lightning.qubit", wires=4, shots=5)
  
  @qml.qnode(dev)
  def circuit():
    qml.Hadamard(wires=0)
    qml.CNOT(wires=[0, 1])
    return qml.expval(qml.PauliY(wires=0))
  
  @qjit(keep_intermediate=True)
  def mitigated_circuit():
    s = jax.numpy.array([1, 2, 3])
    return mitigate_with_zne(
      circuit,
      scale_factors=s,
      extrapolate=exponential_extrapolate,
      folding="local-all" # "local-all" for local on all gates or "global" for the original method (default being "global")
    )()
  

  >>> circuit()
  >>> mitigated_circuit()
  

Improvements

• Fixes an issue where certain JAX linear algebra functions from jax.scipy.linalg gave incorrect results when invoked from within a qjit block, and adds full support for other jax.scipy.linalg functions. (#1097)

  The supported linear algebra functions include, but are not limited to:

  • ``jax.scipy.linalg.cholesky` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.cholesky.html>`_

  • ``jax.scipy.linalg.expm` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.expm.html>`_

  • ``jax.scipy.linalg.funm` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.funm.html>`_

  • ``jax.scipy.linalg.hessenberg` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.hessenberg.html>`_

  • ``jax.scipy.linalg.lu` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.lu.html>`_

  • ``jax.scipy.linalg.lu_solve` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.lu_solve.html>`_

  • ``jax.scipy.linalg.polar` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.polar.html>`_

  • ``jax.scipy.linalg.qr` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.qr.html>`_

  • ``jax.scipy.linalg.schur` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.schur.html>`_

  • ``jax.scipy.linalg.solve` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.solve.html>`_

  • ``jax.scipy.linalg.sqrtm` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.sqrtm.html>`_

  • ``jax.scipy.linalg.svd` <https://jax.readthedocs.io/en/latest/_autosummary/jax.scipy.linalg.svd.html>`_

Breaking changes

• The argument scale_factors of mitigate_with_zne function now follows the proper literature definition. It now needs to be a list of positive odd integers, as we don’t support the fractional part. (#1120)

Bug fixes

• Those functions calling the gather_p primitive (like jax.scipy.linalg.expm) can now be used in multiple qjits in a single program. (#1096)

Contributors

This release contains contributions from (in alphabetical order):

Joey Carter, Alessandro Cosentino, Paul Haochen Wang, David Ittah, Romain Moyard, Daniel Strano, Raul Torres.

releases/changelog-0.8.1

 

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