Can a quantum circuit detect the Unruh effect?
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 -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 shift in the ground-state population within 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.
Cite
@article{arxiv.2607.24836,
title = {Can a quantum circuit detect the Unruh effect?},
author = {Pravin Kumar Dahal and Timothy C. Ralph and William J. Munro and Arkady Fedorov and James Q. Quach},
journal= {arXiv preprint arXiv:2607.24836},
year = {2026}
}
Comments
11 pages, 4 figures; Comments Welcome!