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arXiv:2610.20202 · Physical Review Applied

A hybrid quantum interferometer bridging Hong-Ou-Mandel and N00N-state interference

Zi-Qi Zeng, Samuel Corona-Aquino, Tao Xie, Bin Yin, Yan Guo, Yukun Song, Yun Meng, Kai Zou, Song Li, Xiaolong Hu, Alfred B. U'Ren, Roberto de J. León-Montiel, Chenglong You, Baihong Li, Dongzhou Wang, Rui-Bo Jin

quant-phSubmitted Oct 14, 2026• Announced Oct 15, 2026• 0 citations
arXivHTMLPDF

Abstract

Hong-Ou-Mandel (HOM) interference offers robustness in high-noise environments due to its phase-insensitive nature, while N00N-state interference provides enhanced phase sensitivity for precision measurements in low-noise settings. However, their realizations have typically required separate experimental platforms. Here, we report a single hybrid quantum interferometer that can dynamically transition between HOM and N00N-state interference by adjusting two time delays, $τ_1$ and $τ_2$. This tunability enables operation in phase-insensitive, phase-sensitive, or hybrid modes within a unified setup, as confirmed by theoretical analysis and experimental demonstration. Our system offers a versatile platform with potential for quantum sensing applications, paving the way for integrated quantum technologies capable of adapting to diverse noise conditions.

Journal reference
Physical Review APPLIED 26, 044035 (2026)
DOI
10.1103/pd91-dyf9
Comments
13 pages, 7 figures

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Hong-Ou-Mandel (HOM) interference offers robustness in high-noise environments due to its phase-insensitive nature, while N00N-state interference provides enhanced phase sensitivity for precision measurements in low-noise settings. However, their realizations have typically required separate experimental platforms. Here, we report a single hybrid quantum interferometer that can dynamically transition between HOM and N00N-state interference by adjusting two time delays, τ1τ_1τ1​ and τ2τ_2τ2​. This tunability enables operation in phase-insensitive, phase-sensitive, or hybrid modes within a unified setup, as confirmed by theoretical analysis and experimental demonstration. Our system offers a versatile platform with potential for quantum sensing applications, paving the way for integrated quantum technologies capable of adapting to diverse noise conditions.
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.
Quantum interference forces two indistinguishable input photons to depart a beamsplitter in the same (of two possible) spatial output modes; this is known as the Hong-Ou-Mandel (HOM) effect. It provides a quantitative way of measuring the distinguishability between two photons and also has been utilised to determine their relative temporal delays [1, 2]. HOM interferometry offers numerous advantages over its classical counterpart, most importantly it lacks any dependence on the phase of the photons and therefore can potentially provide reliable measurements in environments where the phase is unstable. To date there have been very few investigations on the precision that is achievable with HOM interferometry. Experiments with collinear geometries have yielded sensitivities as low as 0.1fs however these approaches are limited to measurements of birefringence and other polarisation dependent effects [3, 4], as the precision derives from the inherently stable shared path of the photon pairs. Typical non-shared path HOM interferometers exhibit resolution of roughly 1–3 fs (0.3–1 μm).
The use of quantum properties of light has allowed researchers to create technologies that can outperform classical setups. In quantum imaging and sensing, the cross-correlation of photon pairs enables precise time synchronization of photons reaching the photodetectors, effectively suppressing environmental noise, and improving measurement accuracy. Building on this concept, we theoretically introduce and experimentally explore phase-dependent Hong-Ou-Mandel (HOM) interferometry. This technique employs phase-shifted indistinguishable photon pairs in a modified HOM interferometer for detection of microwave signals. We demonstrate that applying a phase shift to photon pairs via electro-optic modulation in the modified HOM interferometer causes a change in the middle interference structure, which can be used to gain information about the microwave signal causing the phase shift. In this work, we explore the quantization of the electromagnetic field, as well as nonclassical states of light. Phase estimation and metrics in quantum metrology are explored to gain insight into the benefits of utilizing these nonclassical states. An understanding of optical interferometry is built by investigating different types of interferometers, before introducing the HOM interferometer. Theory for the modified HOM interferometer is introduced, followed by an exploration of the interference structure that arises from the different path lengths in the modified system. We gathered data experimentally, showing the addition of a phase through electro-optic modulators (EOMs) leads to a change in the height of the structure. From this data, we calculate the Fisher information (FI), and find a maximum sensitivity of 58 mradians for phase difference, and 25 mV for amplitude. Additionally, we theoretically explore the FI to find optimal parameters to increase the system's sensitivity.
Quantum technologies have been widely recognized as unprecedented opportunities for ultra-high precision metrology. As a celebrated example in modern quantum optics, the Hong-Ou-Mandel (HOM) interferometer is well-known for enabling temporal resolutions on the attosecond scale. However, the relatively low Fisher information per trial in ordinary HOM measurements typically necessitates tens of thousands of repetitions to achieve such precision. Here, we propose and demonstrate a sample-half-inserted HOM (SHOM) interferometer, which enhances the Fisher information by five orders of magnitude in a single interference event. By introducing an asymmetric photon-sample interaction, the SHOM configuration produces a distinctive dip-bump-dip interference structure, converting what was previously viewed as an artifact into a helpful metrological resource. Experimentally, we measured the optical path difference with an average precision of 4.09 nm (13.63 as) and an average accuracy of 1.22 nm (4.07 as) using O(107)O(10^7)O(107) photons. Our results establish SHOM interferometry as an efficient phase-insensitive approach, not only paving the way toward practical quantum-enhanced thickness measurement for transparent materials, but also serving as an elegant strategy to improve the performance of various quantum devices.
Traditional Hong-Ou-Mandel (HOM) interferometry, insensitive to photons phase mismatch, proved to be a rugged single-photon interferometric technique. By introducing a post-beam splitter polarization-dependent delay, it is possible to recover phase-sensitive fringes, obtaining a temporal quantum eraser that maintains the ruggedness of the original HOM with enhanced sensitivity. This setup shows promising applications in biological sensing and optical metrology, where high sensitivity requirements are coupled with the necessity to keep light intensity as low as possible to avoid power-induced degradation. In this paper, we developed a highly sensitive single photon birefringence-induced delay sensor operating in the telecom range (1550 nm). By using a temporal quantum eraser based on common path Hongr-Ou-Mandel Interferometry, we were able to achieve a sensitivity of 4 as for an integration time of 2·104 s.
We propose and experimentally demonstrate two-photon interference effects in a Mach-Zehnder interferometer in which two different kinds of two-photon states are prepared by introducing a time delay between the two input photons. The two-photon states are simultaneously prepared in a symmetrically superposed state with two temporally separated photons in two different spatial modes or in the same spatial mode within the interferometer. We observe two-photon interference fringes involving both the Hong-Ou-Mandel interference effect and the interference of path-entangled two-photon states simultaneously in a single interferometric setup. The observed two-photon interference effect can provide a simultaneous observation of the interferometric properties of the single-photon and two-photon wavepackets