Noise Protected Logical Qubit in a Open Chain of Superconducting Qubits with Ultrastrong Interactions

Fuente: arXiv
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Autori principali: Stassi, Roberto, Abo, Shilan, Lamberto, Daniele, Chen, Ye-Hong, Miranowicz, Adam, Savasta, Salvatore, Nori, Franco
Natura: Preprint
Pubblicazione: 2025
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author Stassi, Roberto
Abo, Shilan
Lamberto, Daniele
Chen, Ye-Hong
Miranowicz, Adam
Savasta, Salvatore
Nori, Franco
author_facet Stassi, Roberto
Abo, Shilan
Lamberto, Daniele
Chen, Ye-Hong
Miranowicz, Adam
Savasta, Salvatore
Nori, Franco
contents To achieve a fault-tolerant quantum computer, it is crucial to increase the coherence time of quantum bits. In this work, we theoretically investigate a system consisting of a series of superconducting qubits that alternate between XX and YY ultrastrong interactions. By considering the two-lowest energy eigenstates of this system as a {\it logical} qubit, we demonstrate that its coherence is significantly enhanced: both its pure dephasing and relaxation times are extended beyond those of individual {\it physical} qubits. Specifically, we show that by increasing either the interaction strength or the number of physical qubits in the chain, the logical qubit's pure dephasing rate is suppressed to zero, and its relaxation rate is reduced to half the relaxation rate of a single physical qubit. Single qubit and two-qubit gates can be performed with a high fidelity.
format Preprint
id arxiv_https___arxiv_org_abs_2509_17903
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Noise Protected Logical Qubit in a Open Chain of Superconducting Qubits with Ultrastrong Interactions
Stassi, Roberto
Abo, Shilan
Lamberto, Daniele
Chen, Ye-Hong
Miranowicz, Adam
Savasta, Salvatore
Nori, Franco
Quantum Physics
Mesoscale and Nanoscale Physics
To achieve a fault-tolerant quantum computer, it is crucial to increase the coherence time of quantum bits. In this work, we theoretically investigate a system consisting of a series of superconducting qubits that alternate between XX and YY ultrastrong interactions. By considering the two-lowest energy eigenstates of this system as a {\it logical} qubit, we demonstrate that its coherence is significantly enhanced: both its pure dephasing and relaxation times are extended beyond those of individual {\it physical} qubits. Specifically, we show that by increasing either the interaction strength or the number of physical qubits in the chain, the logical qubit's pure dephasing rate is suppressed to zero, and its relaxation rate is reduced to half the relaxation rate of a single physical qubit. Single qubit and two-qubit gates can be performed with a high fidelity.
title Noise Protected Logical Qubit in a Open Chain of Superconducting Qubits with Ultrastrong Interactions
topic Quantum Physics
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2509.17903