Detecting phase transitions in an optical microcavity

Zhang, Jianjun, Yuan +4 more

张建军, 袁建辉, 张俊佩 +1 more

Jian‐Jun Zhang, Jianhui Yuan, Junpei Zhang +1 more

We analyze the ground-state properties and the excitation spectrum of Bose—Einstein condensates of photons and PPs in a two-dimensional optical microcavity. First, using the variational method, we discuss the ground-state phase transition of the two-component system. We also investigate the energy gap between the ground state and the first excited state. Moreover, by investigating the excitation spectrum, we also illustrate how the superfluid behavior of photons and PPs can be associated with the phase transition of the system.

Qi-Tao Cao, Yun‐Feng Xiao

Qi Song, Hongjing Li, Ding Wang +5 more

ABSTRACT High‐sensitivity optical microcavity sensing faces the challenge of limited dynamic range for detecting time‐varying signals. To address the challenge, an enhanced optical microcavity sensing approach is proposed by integrating an extended polarization interferometer with postselection. The approach exploits both transmission and phase characteristics of the microcavity simultaneously. By adjusting coupling strength and postselection angle, the approach creates distinct phase response regions, thereby achieving significantly improved response compared to the standard transmission method. The dynamic range extends from at most twice the full width at half maximum to the free spectral range. The gain factor depends on material properties, cavity size, resonant wavelength, and quality factor, potentially reaching three to four orders of magnitude for cavities with a quality factor of 10 8 . Furthermore, the approach is compatible with quantum resources, enabling the potential for precision beyond the standard quantum limit. By exploiting the differences between dual‐polarized cavity modes, the feasibility is verified by combining the approach with a polarization Sagnac interferometer. Experimental results demonstrate over 34.24 dB improvement in detection sensitivity, and an additional 12.29 dB enhancement is achieved using coherent states and heterodyne detection. The approach offers a promising solution for optical microcavity sensing across various scenarios.