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Main Authors: Zammit, Hayden, Salazar, Roberto, Valentino, Gianluca, Briffa, Johann A., Apollaro, Tony J. G.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.05661
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author Zammit, Hayden
Salazar, Roberto
Valentino, Gianluca
Briffa, Johann A.
Apollaro, Tony J. G.
author_facet Zammit, Hayden
Salazar, Roberto
Valentino, Gianluca
Briffa, Johann A.
Apollaro, Tony J. G.
contents Quantum Information Processing (QIP) tasks can be efficiently formulated in terms of quantum dynamical maps, whose formalism is able to provide the appropriate mathematical representation of the evolution of open quantum systems. A key QIP task is quantum state transfer (QST) aimed at sharing quantum information between distant nodes of a quantum network, enabling, e.g. quantum key distribution and distributed quantum computing. QST has primarily been addressed insofar by resetting the quantum channel after each use, thus giving rise to memoryless channels. Here we consider the case where the quantum channel is continuously used, without implementing time- and resource- consuming resetting operations. We derive a general, analytical expression for the $n^{\mathrm{th}}$-use average QST fidelity for $U(1)$-symmetric channels and apply our formalism to a perfect QST channel in the presence of imperfect readout timing. We show that even relatively small readout timing errors give rise to memory effects which have a highly detrimental impact on subsequent QST tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2511_05661
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Memory effects in repeated uses of quantum channels
Zammit, Hayden
Salazar, Roberto
Valentino, Gianluca
Briffa, Johann A.
Apollaro, Tony J. G.
Quantum Physics
Quantum Information Processing (QIP) tasks can be efficiently formulated in terms of quantum dynamical maps, whose formalism is able to provide the appropriate mathematical representation of the evolution of open quantum systems. A key QIP task is quantum state transfer (QST) aimed at sharing quantum information between distant nodes of a quantum network, enabling, e.g. quantum key distribution and distributed quantum computing. QST has primarily been addressed insofar by resetting the quantum channel after each use, thus giving rise to memoryless channels. Here we consider the case where the quantum channel is continuously used, without implementing time- and resource- consuming resetting operations. We derive a general, analytical expression for the $n^{\mathrm{th}}$-use average QST fidelity for $U(1)$-symmetric channels and apply our formalism to a perfect QST channel in the presence of imperfect readout timing. We show that even relatively small readout timing errors give rise to memory effects which have a highly detrimental impact on subsequent QST tasks.
title Memory effects in repeated uses of quantum channels
topic Quantum Physics
url https://arxiv.org/abs/2511.05661