University of Oulu

Busel, O., Laine, S., Mansikkamäki, O., & Silveri, M. (2023). Dissipation and dephasing of interacting photons in transmon arrays. Physical Review Research, 5(2), 023121.

Dissipation and dephasing of interacting photons in transmon arrays

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Author: Busel, Oksana1; Laine, Sami1,2; Mansikkamäki, Olli1;
Organizations: 1Nano and Molecular Systems Research Unit, University of Oulu, Oulu 90014, Finland
2Department of Information Technology, Oulu University of Applied Sciences, Oulu 90101, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.9 MB)
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Language: English
Published: American Physical Society, 2023
Publish Date: 2023-05-30


Transmon arrays are one of the most promising platforms for quantum information science. Despite being often considered simply as qubits, transmons are inherently quantum mechanical multilevel systems. Being experimentally controllable with high fidelity, the higher excited states beyond the qubit subspace provide an important resource for hardware-efficient many-body quantum simulations, quantum error correction, and quantum information protocols. Alas, dissipation and dephasing phenomena generated by couplings to various uncontrollable environments yield a practical limiting factor to their utilization. To quantify this in detail, we present here the primary consequences of single-transmon dissipation and dephasing to the many-body dynamics of transmon arrays. We use analytical methods from perturbation theory and quantum trajectory approach together with numerical simulations, and deliberately consider the full Hilbert space, including the higher excited states. The three main nonunitary processes are many-body decoherence, many-body dissipation, and heating/cooling transitions between different anharmonicity manifolds. Of these, the many-body decoherence—being proportional to the squared distance between the many-body Fock states—gives the strictest limit for observing effective unitary dynamics. Considering experimentally relevant parameters, including also the inevitable site-to-site disorder, our results show that the state-of-the-art transmon arrays should be ready for the task of demonstrating coherent many-body dynamics using the higher excited states. However, the wider utilization of transmons for ternary-and-beyond quantum computing calls for improving their coherence properties.

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Series: Physical review research
ISSN: 2643-1564
ISSN-E: 2643-1564
ISSN-L: 2643-1564
Volume: 5
Issue: 2
Article number: 023121
DOI: 10.1103/physrevresearch.5.023121
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
Copyright information: Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.