An enhanced distributed acoustic sensing (DAS) is proposed based on an extended Mach-Zehnder interferometer utilizing quantum weak measurement. The acoustic signals are encoded as the relative phase of the polarized light in several channels by fibers between optical fiber Bragg gratings (FBGs). With appropriate preselection and postselection, the acoustic signal can be extracted by performing the Fourier transform on the contrast ratio of the detected light intensity. Theoretical analysis shows that the scheme can achieve a spatial resolution of 1 m, and the system noise can be decreased by three orders of magnitude compared to classical distributed acoustic sensing. Moreover, this scheme might have potential application in long-distance acoustic source localization.
An enhanced distributed acoustic sensing (DAS) is proposed based on an extended Mach-Zehnder interferometer utilizing quantum weak measurement. The acoustic signals are encoded as the relative phase of the polarized light in several channels by fibers between optical fiber Bragg gratings (FBGs). With appropriate preselection and postselection, the acoustic signal can be extracted by performing the Fourier transform on the contrast ratio of the detected light intensity. Theoretical analysis shows that the scheme can achieve a spatial resolution of 1 m, and the system noise can be decreased by three orders of magnitude compared to classical distributed acoustic sensing. Moreover, this scheme might have potential application in long-distance acoustic source localization.
In fiber optic sensing, time delays induced by polarization mode dispersion can distort signals in systems relying on phase or intensity variations for measurement, degrading performance, especially in long distance, high-precision applications. To address this challenge, we propose a weak measurement-based scheme using intensity contrast ratio for high-precision, high-sensitivity fiber optic delay estimation under large inherent time delays. We demonstrate that a narrower light source bandwidth enhances the effective sensing distance for high-sensitivity measurements. Our results show that, even with large inherent time delays, the measurement precision and sensitivity remain comparable to those of biased weak measurement, enabling detection of time delay variations at the attosecond level, corresponding to a 25.5 Pa water pressure change. The scheme is also robust against fiber misalignment errors, offering a novel solution for long-distance distributed fiber-optic sensing and broadening the applications of weak measurement techniques.
Abstract Reliable detection of weak phase signals under significant channel loss and complex noise environments is a crucial step for practical applications of optical integrated communication and sensing systems. In this letter, we propose and experimentally demonstrate an enhanced long-distance weak signal transmission method assisted by weak measurement. Performing heterodyne detection and light intensity compensation on two nearly symmetric post-selected paths, the method enables real-time estimation of a time-varying phase while maintaining robustness against technical noises proportional to light intensity or photon number, detector common-mode noise, and significant attenuation over long-distance transmission. Experimental results indicate a potential phase sensitivity at the level of 10 −8 rad even with a signal light intensity attenuation of 48.1 dB. Potentially, combining the adaptive adjustment strategy, the method may provide a viable solution in remote weak signal detection and extraction, thereby contributing to optical integrated communication and sensing.
In fiber-optic sensing, time delays induced by polarization mode dispersion can distort signals in systems relying on phase or intensity variations for measurement, degrading performance, especially in long distance, high-precision applications. To address this challenge, we propose a weak measurement-based scheme using intensity contrast ratio for high-precision, high-sensitivity fiber-optic time delay estimation under large inherent time delays. We demonstrate that a narrower light source bandwidth enhances the effective sensing distance for high-sensitivity measurements. Our results show that, even with large inherent time delays, the measurement precision and sensitivity remain comparable to those of biased weak measurement, enabling detection of time delay variations at the attosecond level, corresponding to a 25.5 Pa water pressure change. The scheme is also robust against fiber misalignment errors, offering a novel solution for long-distance distributed fiber-optic sensing and broadening the applications of weak measurement techniques.
We propose distributed dual-comb spectroscopy, a quantum-enhanced sensing architecture that simultaneously exploits spatial- and spectral-domain entanglement to improve the extraction of global spectroscopic information across broadband frequency ranges. Our scheme consists of a network of Mach-Zehnder interferometers interrogating spatially separated samples, each driven by a classical frequency comb at the bright port. A single two-mode squeezed frequency comb is distributed through a passive beam-splitter array into K entangled combs, establishing multipartite correlations across sensors while preserving intrinsic spectral entanglement. The protocol is compatible with both heterodyne detection and division detection, and enables parallel estimation of weighted-average absorption features over multiple frequency components. Compared with spatially separable quantum strategies requiring K independently engineered nonclassical comb sources, our approach achieves enhanced signal-to-noise performance using only a single quantum resource distributed across the network. These results establish a scalable route toward broadband distributed quantum spectroscopy with simultaneous spatial and spectral advantage.
We propose and experimentally demonstrate a quantum-enhanced fiber Mach-Zehnder interferometer for low-frequency phase measurement beyond the shot-noise limit using a high-frequency squeezing technique. The local oscillator field is amplitude-modulated in the MHz range and is then demodulated to avoid the technical noise that occurs at low frequencies. After measurement of the phase noise at a frequency of tens of kHz, an improvement of ∼2 dB relative to the shot-noise level is achieved. Additionally, the amplitude modulation depth has no significant effect on the phase noise improvement of the interferometer when deployed in our experimental configuration. The current scheme introduces a quantum technique into the fiber-based measurements, particularly for the low frequency range, and this scheme has potential applications in the high-precision fiber sensing of temperature, strain, and various other parameters.
Quantum sensing has performance advantages that far exceed classical sensing, where sensing with photons is one of the most useful branches, and fiberization is a significant development approach to achieve a broader range of applications. However, the birefringence effect in optical fibers can cause polarization drift, which severely reduces the sensitivity of measurement on weak signals and influences the development of quantum sensing. In order to solve this problem, we propose a scheme that builds four time-division-multiplexing channels in the system by switching the polarization states of different optical pulses, and achieves the effect of suppressing polarization drift by analyzing and integrating the effective information of the four polarization channels. Moreover, the sensitivity and linear dynamic range of the system can be adjusted by inserting a reference phase. We demonstrate the feasibility of the system via theoretical analysis, and the numerical simulation results show that the scheme can demodulate the signal well and improve the signal-to-noise ratio by 30 dB, even in the case of the signal of the direct demodulation method is drowned out by noise and completely distorted.