A hybrid quantum-classical algorithm for Bayes-optimal quantum state discrimination using the source code

Fuente: arXiv
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Autori principali: Mohan, Ankith, Sikora, Jamie, Upadhyay, Sarvagya
Natura: Preprint
Pubblicazione: 2023
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author Mohan, Ankith
Sikora, Jamie
Upadhyay, Sarvagya
author_facet Mohan, Ankith
Sikora, Jamie
Upadhyay, Sarvagya
contents Quantum state discrimination is a fundamental primitive in quantum information processing, underpinning tasks in quantum communication, sensing, and learning. We consider the general Bayes framework, as introduced by Helstrom, for state discrimination when, instead of a classical description of the candidate states, one has access to their \emph{source code}: the quantum circuit that prepares them. We show that the semidefinite program (SDP) for the discrimination problem can be reformulated in terms of the Gram matrix of these states, reducing the SDP variable dimensions from $dL$ to $NL$, where $d$ is the Hilbert space dimension, $N$ is the number of candidate states, and $L$ is the number of possible guesses. Importantly, we further introduce a quantum pre-processing procedure which efficiently constructs the reduced semidefinite program from the source code, enabling our method to operate directly on quantum data. We consider two applications. First, we characterize the optimal identifications for quantum changepoint problems under several reward structures, including multiple-changepoint settings that were previously computationally inaccessible. Second, we consider a quantum error classification problem and show how our reduction makes it tractable for systems of hundreds of qubits.
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id arxiv_https___arxiv_org_abs_2312_04023
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle A hybrid quantum-classical algorithm for Bayes-optimal quantum state discrimination using the source code
Mohan, Ankith
Sikora, Jamie
Upadhyay, Sarvagya
Quantum Physics
Quantum state discrimination is a fundamental primitive in quantum information processing, underpinning tasks in quantum communication, sensing, and learning. We consider the general Bayes framework, as introduced by Helstrom, for state discrimination when, instead of a classical description of the candidate states, one has access to their \emph{source code}: the quantum circuit that prepares them. We show that the semidefinite program (SDP) for the discrimination problem can be reformulated in terms of the Gram matrix of these states, reducing the SDP variable dimensions from $dL$ to $NL$, where $d$ is the Hilbert space dimension, $N$ is the number of candidate states, and $L$ is the number of possible guesses. Importantly, we further introduce a quantum pre-processing procedure which efficiently constructs the reduced semidefinite program from the source code, enabling our method to operate directly on quantum data. We consider two applications. First, we characterize the optimal identifications for quantum changepoint problems under several reward structures, including multiple-changepoint settings that were previously computationally inaccessible. Second, we consider a quantum error classification problem and show how our reduction makes it tractable for systems of hundreds of qubits.
title A hybrid quantum-classical algorithm for Bayes-optimal quantum state discrimination using the source code
topic Quantum Physics
url https://arxiv.org/abs/2312.04023