generate_shifted_tapes(tape, index, shifts, multipliers=None, broadcast=False)[source]

Generate a list of tapes or a single broadcasted tape, where one marked trainable parameter has been shifted by the provided shift values.

Parameters
• tape (QuantumTape) – input quantum tape

• index (int) – index of the trainable parameter to shift

• shifts (Sequence[float or int]) – sequence of shift values. The length determines how many parameter-shifted tapes are created.

• multipliers (Sequence[float or int]) – sequence of multiplier values. The length should match the one of shifts. Each multiplier scales the corresponding gate parameter before the shift is applied. If not provided, the parameters will not be scaled.

• broadcast (bool) – Whether or not to use broadcasting to create a single tape with the shifted parameters.

Returns

List of quantum tapes. In each tape the parameter indicated

by index has been shifted by the values in shifts. The number of tapes matches the length of shifts and multipliers (if provided). If broadcast=True was used, the list contains a single broadcasted tape with all shifts distributed over the broadcasting dimension. In this case, the batch_size of the returned tape matches the length of shifts.

Return type

list[QuantumTape]