In quantum theory, measurement is usually thought as a destructive operation, turning quantum superpositions into classical outcomes. However, it can also be used to drive non-trivial quantum dynamics as exemplified by measurement-based quantum computation as well as ancilla-driven quantum computation. The back-action onto a system due to its measurement can lead to various types of evolution, from complete projection to a single state, to coherent unitary rotations, as well as intermediate outcomes.

Recent results include the ability to generate holonomic quantum gates using degenerate projections [1], and showing methods of reversing measurement (“unlearning quantum information” [2]) as well as demonstrating its bounds. More generally, we are interested in characterizing the ability of various system-probe interactions to perform different functions, from extracting information to implementing general completely-positive quantum maps.

Researchers: Daniel Oi

PUBLICATIONS

[1] Unitary holonomies by direct degenerate projections, Daniel K. L. Oi, Phys. Rev. A 89, 050102(R) (2014).

[2] Unlearning Quantum Information, Daniel K. L. Oi, The European Physical Journal D volume 68, 259 (2014).