Controlling dephasing of coupled qubits via shared bath coherence

Hall, L. M., Sirkina, L. S., Morreau, A., Langbein, W. ORCID: https://orcid.org/0000-0001-9786-1023 and Muljarov, E. A. ORCID: https://orcid.org/0000-0002-2878-4148 2025. Controlling dephasing of coupled qubits via shared bath coherence. Physical Review B (condensed matter and materials physics) 10.1103/ltk8-fpv3 Item availability restricted.

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Abstract

The interaction of a quantum system with its environment limits its coherence time. This, in particular, restricts the utility of qubits in quantum information processing applications. In this paper, we show that the decoherence of a coupled qubit system can be minimized, or even eliminated, by exploiting the quantum coherence of the bath itself. We investigate the dephasing in a system of two spatially separated, electronically decoupled qubits, with direct or mediated coupling, interacting with a shared bath. For illustration, we treat F"orster or cavity-mediated coupling between semiconductor quantum dots interacting with acoustic phonons. Using the rigorous method of Trotter’s decomposition with cumulant expansion, we demonstrate a reduction in the dephasing rates at specific distances between the dots. The control of dephasing with distance is a coherent effect of the shared bath and is absent for independent baths. It can be understood in terms of phonon-assisted transitions between the entangled qubit states of the coupled system.

Item Type:	Article
Status:	In Press
Schools:	Schools > Physics and Astronomy
Publisher:	American Physical Society
ISSN:	2469-9950
Date of First Compliant Deposit:	24 June 2025
Date of Acceptance:	9 June 2025
Last Modified:	26 Jun 2025 09:15
URI:	https://orca.cardiff.ac.uk/id/eprint/179294

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