Noise and Interferometry

Jungsang Kim, Seema Somani, Y. Yamamoto

Ángel S. Sanz, Salvador Miret-Artés

Chen Fang, Jingzheng Huang, Guihua Zeng

Optical interferometry has been widely used in various high-precision applications. Usually, the minimum precision of an interferometry is limited by various technical noises in practice. To suppress such kinds of noises, we propose a scheme which combines the weak measurement with the standard interferometry. The proposed scheme dramatically outperforms the standard interferometry in the signal-to-noise ratio and the robustness against noises caused by the optical elements' reflections and the offset fluctuation between two paths. A proof-of-principle experiment is demonstrated to validate the amplification theory.

Peng Yang, Boya Xie, Sheng Feng

Quantum noise limited interferometry for subhertz phase measurement is of essence in precision metrology applications, such as gravitational wave detection. However, suppression of subhertz classical noises below the shot-noise level is very challenging in practice. Two-frequency interferometry has been previously proposed to avoid low-frequency noises and may be useful for squeezing-enhanced high-precision phase measurement. Here we experimentally demonstrate a subhertz interferometer at the standard quantum noise (shot-noise) limit, by use of dual-frequency coherent probe light at the input and phase-sensitive heterodyne detection to measure the output interfered light. When the interferometer is locked at a dark fringe, the noise floor of the phase variance in the interferometer reaches the shot-noise level down to Fourier frequencies below 1 Hz. This work should pave a way for a realization of subhertz interferometry beyond the shot-noise limit.

Teng-fei Yan, Zhuo-zhuo Wang, Qi-qi Li +3 more

Quantum sensing based on two-photon interferometry manifests quantum superiority beyond the classical precision limit. However, this superiority is usually diminished inevitably by the noise. Here, we analyze the sensitivity of two typical two-photon interferometries to the noise, that is, Hong-Ou-Mandel (HOM) and N00N state interferometry. It is found that HOM (N00N state) interference, which depends on the biphoton frequency difference (sum), is insensitive (sensitive) to the phase noise in both the manners of spectrally non-resolved and resolved detections in practice, suggesting their potential applications of sensing for different noise scenarios. Furthermore, spectrally resolved detection outperforms spectrally non-resolved one for the two interferometries, especially for the scope that exceeds the coherence time of biphotons. The findings provide an optimal strategy for the practical applications of two-photon interferometric sensing in diverse noise environments.

Lawrence N. Mertz