2026-04-15 九州大学
図１. 光を用いた鏡の連続位置測定とフィルタリングの流れ：レーザー光を光共振器に入射し、可動鏡の位置を連続的に測定する。出力光はホモダイン検出(※6)によって読み出され、その測定データを最適フィルタリングの手法を用いて解析することで、鏡の量子状態を高精度に推定することができる。
＜関連情報＞
- https://www.kyushu-u.ac.jp/ja/researches/view/1453
- https://www.kyushu-u.ac.jp/f/65700/26_0415_02.pdf
- https://journals.aps.org/prresearch/abstract/10.1103/zrs2-sk28
光力学における最適フィルタリングによって実現される運動量圧縮状態：重力誘起エンタングルメントへの示唆 Momentum squeezed state realized via optimal filtering in optomechanics: Implications for gravity-induced entanglement
Ryotaro Fukuzum, Kosei Hatakeyama, Daisuke Miki, and Kazuhiro Yamamoto
Physical Review Research Published: 13 April, 2026
DOI: https://doi.org/10.1103/zrs2-sk28
Abstract
We analyze the conditional quantum state of a mechanical mirror in an optomechanical system subject to continuous measurement, feedback control, and quantum filtering. We identify a parameter regime in which the mirror exhibits momentum squeezing beyond the standard quantum limit, achieved through an appropriate choice of the homodyne detection angle. In this regime, we show that optimal filtering effectively realizes a free-particle-like conditional state. When this mechanism is applied to a configuration consisting of two optomechanical systems, the resulting momentum squeezing significantly enhances the signal of gravity-induced entanglement. This enhancement arises because the momentum squeezing not only amplifies the distinction between the common and differential modes, but also, in the high-purity regime, increases the position uncertainty in accordance with the uncertainty principle, thereby enlarging the spatial extent of the quantum superposition. Our results provide insights into experimental strategies for probing the quantum nature of gravity using optomechanical platforms.
