2026-09-03 産業技術総合研究所
磁束量子によって光子を検出する原理のイメージ
＜関連情報＞
- https://www.aist.go.jp/aist_j/press_release/pr2026/pr20260903_2/pr20260903_2.html
- https://journals.aps.org/prapplied/abstract/10.1103/n295-rfl8
超伝導薄膜における光子誘起渦の直接観察 Direct observation of photon-induced vortices in superconducting films
Takeshi Jodoi, Fuminori Hirayama, Tetsuya Tsuruta, Takahiro Kikuchi, and Daiji Fukuda
Physical Review Applied Published: 2 September, 2026
DOI: https://doi.org/10.1103/n295-rfl8
Abstract
Nucleation of vortex-antivortex pairs (VAPs) is believed to play a central role in the photon detection mechanism of superconducting detectors; however, their direct dynamic observation has remained challenging. Here, we report the direct observation of photon-induced VAP dynamics in a current-carrying superconductor as quantized voltage signals following photon absorption. The observed signals are interpreted as discrete phase-slip events, where each vortex traversal induces a 2 phase change of the superconducting order parameter, resulting in a quantized voltage pulse whose time integral is given by the magnetic flux quantum Φ0. We analyze the resulting quantized signals as a function of bias current, base temperature, and input photon-number states and find that the number of VAPs generated per absorbed photon becomes effectively stabilized under specific conditions. Under these conditions, we demonstrate photon-number-resolving capability by directly counting phase-slip-induced voltage quanta. Our results reveal a detection mechanism governed by phase dynamics rather than conventional resistive transitions and represent the first demonstration of photon-number resolution based on VAP counting, enabling fast multi-photon-resolving superconducting detectors for quantum optics.
