The quantum switch is uniquely defined by its action on unitary operations

Autor(en)

Qingxiuxiong Dong, Marco Túlio Quintino, Akihito Soeda, Mio Murao

Abstrakt

The quantum switch is a quantum process that creates a coherent control between different unitary operations, which is often described as a quantum process which transforms a pair of unitary operations (U₁, U₂) into a controlled unitary operation that coherently applies them in different orders as |0〉〈0| & U₁U₂ + |1〉〈1| &U₂U₁. This description, however, does not directly define its action on non-unitary operations. The action of the quantum switch on non-unitary operations is then chosen to be a “natural” extension of its action on unitary operations. In general, the action of a process on non-unitary operations is not uniquely determined by its action on unitary operations. It may be that there could be a set of in-equivalent extensions of the quantum switch for non-unitary operations. We prove, however, that the natural extension is the only possibility for the quantum switch for the 2-slot case. In other words, contrary to the general case, the action of the quantum switch on non-unitary operations (as a linear and completely CP preserving supermap) is completely determined by its action on unitary operations. We also discuss the general problem of when the complete description of a quantum process is uniquely determined by its action on unitary operations and identify a set of single-slot processes which are completely defined by their action on unitary operations.

Organisation(en)

Quantenoptik, Quantennanophysik und Quanteninformation

Externe Organisation(en)

University of Tokyo, National Institute of Informatics, Graduate University for Advanced Studies , Icm & Sorbonne University, Österreichische Akademie der Wissenschaften (ÖAW)

Journal

Quantum

Band

7

Anzahl der Seiten

24

ISSN

2521-327X

DOI

https://doi.org/10.22331/q-2023-11-07-1169

Publikationsdatum

2023

Peer-reviewed

Ja

ÖFOS 2012

103025 Quantenmechanik

ASJC Scopus Sachgebiete

Atomic and Molecular Physics, and Optics, Physics and Astronomy (miscellaneous)

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/77469453-53d4-483a-bfd9-b486e522cd76