qml.workflow.interfaces.autograd.vjp

vjp(ans, parameters, tapes, execute_fn, jpc)[source]

Returns the vector-Jacobian product operator for a batch of quantum tapes.

Parameters
  • ans (array) – the result of the batch tape execution

  • parameters (list[list[Any]]) – Nested list of the quantum tape parameters. This argument should be generated from the provided list of tapes.

  • tapes (Sequence[QuantumTape]) – batch of tapes to execute

  • execute_fn (Callable[[Sequence[QuantumTape]], ResultBatch]) – a function that turns a batch of circuits into results

  • jpc (JacobianProductCalculator) – a class that can compute the vector Jacobian product (VJP) for the input tapes.

Returns

this function accepts the backpropagation gradient output vector, and computes the vector-Jacobian product

Return type

function