Unitary-invariant witnesses of quantum imaginarity

Fuente: arXiv
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Main Authors: Fernandes, Carlos, Wagner, Rafael, Novo, Leonardo, Galvão, Ernesto F.
Format: Preprint
Published: 2024
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author Fernandes, Carlos
Wagner, Rafael
Novo, Leonardo
Galvão, Ernesto F.
author_facet Fernandes, Carlos
Wagner, Rafael
Novo, Leonardo
Galvão, Ernesto F.
contents Quantum theory is traditionally formulated using complex numbers. This imaginarity of quantum theory has been quantified as a resource with applications in discrimination tasks, pseudorandomness generation, and quantum metrology. Here we propose witnesses for imaginarity that are basis-independent, relying on measurements of unitary-invariant properties of sets of states. For 3 pure states, we completely characterize the invariant values attainable by quantum theory, and give a partial characterization for 4 pure states. We show that simple pairwise overlap measurements suffice to witness imaginarity of sets of 4 states, but not for sets of 3. Our witnesses are experimentally friendly, opening up a new path for measuring and using imaginarity as a resource.
format Preprint
id arxiv_https___arxiv_org_abs_2403_15066
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Unitary-invariant witnesses of quantum imaginarity
Fernandes, Carlos
Wagner, Rafael
Novo, Leonardo
Galvão, Ernesto F.
Quantum Physics
Quantum theory is traditionally formulated using complex numbers. This imaginarity of quantum theory has been quantified as a resource with applications in discrimination tasks, pseudorandomness generation, and quantum metrology. Here we propose witnesses for imaginarity that are basis-independent, relying on measurements of unitary-invariant properties of sets of states. For 3 pure states, we completely characterize the invariant values attainable by quantum theory, and give a partial characterization for 4 pure states. We show that simple pairwise overlap measurements suffice to witness imaginarity of sets of 4 states, but not for sets of 3. Our witnesses are experimentally friendly, opening up a new path for measuring and using imaginarity as a resource.
title Unitary-invariant witnesses of quantum imaginarity
topic Quantum Physics
url https://arxiv.org/abs/2403.15066