Iterable Demuxing#

demux(input, ctrl_qv, output=None, ctrl_method=None, permit_mismatching_size=False, parallelize_qc=False)[source]#

This functions allows moving an input value into an iterable output, where the position is specified by a QuantumFloat. Demux is short for demultiplexer and is a standard component in classical electrical circuitry.

Demux can either move qubit states into a QuantumVariable or QuantumVariables into QuantumArrays.

This function can also be used to “in-place demux” the 0-th entry of an iterable to the position specified by ctrl_qv. For more information on this, check the second example.

Parameters:

inputQubit or QuantumVariable: The input value that is supposed to be moved.
ctrl_qvQuantumFloat: The QuantumFloat specifying to which output the input should be moved.
outputQuantumVariable or QuantumArray, optional: The output object, where the input should end up. By default, a new object (QuantumVariable or QuantumArray) is created. Note that when this parameter is given, it is guaranteed, that the 0-th entry will be moved to the desired position, the other entries can also be permuted away from their original position.
ctrl_methodstring, optional: The ctrl_method string passed to the control environment to generate controlled swaps.
permit_mismatching_sizebool, optional: If set to False, an exception will be raised, if the state-space dimension of ctrl_qv` is differing from the amount of outputs. The default is False.
parallelize_qcbool, optional: If set to True, this option reduces (de)allocates additional qubits to reduce the depth. The default is False.

Returns:

outputQuantumVariable or QuantumArray: The output object with the input signal placed at the index specified by ctrl_qv.

Raises:

Exception: Tried to demux with mismatchingly sized control input.

Examples

We create a QuantumBool and demux it into a QuantumArray

from qrisp import *

qb = QuantumBool()
qb.flip()

index = QuantumFloat(2)

h(index[1])

res_array = demux(qb, index)

>>> print(multi_measurement([index, res_array]))
{(0, OutcomeArray([1., 0., 0., 0.])): 0.5, (2, OutcomeArray([0., 0., 1., 0.])): 0.5}

Demux can also be used to move the 0-th entry of a QuantumArray in-place.

qa = QuantumArray(shape = 4, qtype = qb)

qa[0].flip()

demux(qa[0], index, qa)

>>> print(multi_measurement([index, qa]))
{(0, OutcomeArray([1., 0., 0., 0.])): 0.5, (2, OutcomeArray([0., 0., 1., 0.])): 0.5}

For low-level manipulations, demux can move information within QuantumVariables.

qf = QuantumVariable(4)

qf[:] = "1000"

demux(qf[0], index, qf)

>>> print(multi_measurement([index, qf]))
{(0, '1000'): 0.5, (2, '0010'): 0.5}