Titel
The quantum switch is uniquely defined by its action on unitary operations
Autor*in
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Abstract
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 inequivalent 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.
Objekt-Typ
Sprache
Englisch [eng]
Persistent identifier
phaidra.univie.ac.at/o:2068109
Erschienen in
Titel
Quantum
Band
7
ISSN
2521-327X
Erscheinungsdatum
2023
Seitenanfang
1169
Publication
Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften
Fördergeber
Europäische Union (alle Programme) — 801110
Erscheinungsdatum
2023
Zugänglichkeit
Rechte
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