Optical interference by amplitude measurement

Yunxiao Zhang (Co-first Author), Xuan Tang (Co-first Author), Xueshi Guo, Liang Cui, Xiaoying Li*, Z. Y. Ou*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Abstract

Interference effects are usually observed by intensity measurement. Path indistinguishability by the quantum complementarity principle requires projection of the interfering fields into a common indistinguishable mode before detection. On the other hand, the essence of wave interference is the addition of amplitudes of the interfering fields. Therefore, if amplitudes can be directly measured and added, interference can occur even though the interfering fields are in well-distinguishable modes. Here, we make a comprehensive study in both theory and experiment of a technique by homodyne measurement of field amplitudes to reveal interference. This works for both classical and quantum fields even though there exists distinguishability in the interfering paths of light. This directly challenges the complementarity principle. We present a resolution of this issue from the viewpoint of measurement that emphasizes either particle or wave. This technique is particularly useful for recovering interference in unbalanced interferometers with path imbalance beyond a coherence length of the input field and can be applied to remote sensing to extend the applicable range. Since the amplitude-based interference phenomena studied here are fundamentally different from the traditional intensity-based interference phenomena, our approach leads to a new paradigm to study coherence between optical fields.
Original languageEnglish
Article number013255
JournalPhysical Review Research
Volume7
Issue number1
Online published7 Mar 2025
DOIs
Publication statusPublished - Mar 2025

Funding

This work is supported by the Natural Science Foundation of China (Grants No. 92476113, No. 12461160325), the China Postdoctoral Science Foundation (Grant No. 2024M762347), and by City University of Hong Kong (Project No. 9610522), the General Research Fund from Hong Kong Research Grants Council (Grants No. 11315822, No. 11301624), and Joint NSFC/RGC Collaborative Research Scheme (CRS-CityU103/24).

Publisher's Copyright Statement

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