bibkey: araujo2014unknowncontrol
authors: Mateus Araujo, Adrien Feix, Fabio Costa and Caslav Brukner
year: 2014
title: Quantum circuits cannot control unknown operations
doi: 10.1088/1367-2630/16/9/093026
claim: An unknown quantum operation cannot be coherently controlled by an ordinary fixed circuit using only its black-box channel action.
strata_touched: []
license: citation-only
triage: anchor

Coherent control requires implementation data

The source proves a no-control statement for unknown quantum operations in the circuit setting. The current theory uses the elementary identity Ad(I)=Ad(-I) together with distinguishable controlled versions as a self-contained witness: an ordinary channel does not determine its coherent controlled implementation. This does not forbid control when the physical implementation, reference paths and phases are specified.

Source: https://arxiv.org/abs/1309.7976