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arXiv · 2607.24836

Can a quantum circuit detect the Unruh effect?

Pravin Kumar Dahal·Timothy C. Ralph·William J. Munro·Arkady Fedorov·James Q. Quach
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Abstract

The Unruh effect predicts that an accelerating observer perceives the Minkowski vacuum as a thermal bath, yet direct detection remains experimentally inaccessible. Its timelike counterpart, arising from the entanglement of massless fields between the future and past light cones, offers a more feasible route but requires a detector whose transition frequency follows a specific conformal-time scaling. We propose and analyze a practical implementation of such a detector using superconducting fluxonium circuits, which naturally provide two quasi-degenerate ground states and a tunable excited state, forming an effective $\Lambda$-system. By modulating the excited-state transition frequency in Minkowski time, the detector accumulates a geometric phase associated with the timelike Unruh effect. Open-system simulations predict $\sim 10\%$ shift in the ground-state population within $530$ ns, representing a three-order-of-magnitude sensitivity enhancement over two-level Unruh-DeWitt detectors. These results establish a realistic quantum-circuit platform for experimentally probing the timelike Unruh effect and, more broadly, for testing fundamental nature of quantum fields using engineered quantum systems.

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Pravin Kumar Dahal, Timothy C. Ralph, William J. Munro, Arkady Fedorov, James Q. Quach. 2026-07-24. Can a quantum circuit detect the Unruh effect?. https://arxiv.org/abs/2607.24836

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