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Evolution of biphoton states in ghost imaging with multiple objects

Peiming Li, Xiaojin Chen, Xueyuan Hu, Lijian Zhang, Baoqing Sun

Published Jun 11, 2026• 0 citations

Abstract

Quantum ghost imaging (GI) has significantly advanced the research and application of spatially entangled photon pairs over the past three decades. Nevertheless, existing works predominantly concentrate on qualitative analyses of GI results. The absence of rigorous theoretical models limits the capability of GI to address quantitative problems, which is essential in complex scenarios. Here, we present a comprehensive theoretical model that describes the evolution of the biphoton state throughout the GI process. Based on this model, we can explicitly analyze how the biphoton state evolves, and how object information is encoded into two-photon correlation measurements. We further introduce a virtual single-arm (VSA) operator, which maps the effects of two-arm optical elements into an equivalent single-arm representation, enabling a more intuitive analysis of biphoton-state evolution. Experimental validation is performed using a GI system based on an intensified charge-coupled device (ICCD) camera with multiple objects placed at different longitudinal positions. The excellent agreement between experimental and simulation results confirms the validity of the theoretical framework. This work clarifies the evolution of the biphoton states in quantum GI and opens new avenues for its applications in GI and broader quantum information tasks.

DOI: 10.1364/oe.589465

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Photonic quantum technologies have become pivotal in the implementation of communication, imaging, and computing modalities. Among these applications, quantum ghost imaging (GI) exploits photon correlations to surpass classical limits, with recent advances in spatial-mode encoding and phase imaging. In parallel, all-optical computing offers powerful, passive-light processing capabilities. Here, we explore the intersection of these domains, revealing a conceptual and operational link between GI and Grover’s quantum search algorithm, which is designed to search for elements in an unstructured database. Here, the elements are encoded as phases in the position basis states of photons. To show this, we use entangled photon pairs, with one photon encoding the oracle features, while the other photon is used to find the marked element.

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Ghost imaging (GI) can reconstruct the image of an object by measuring the correlation function of two beams, none of which carries the structure information of the object independently. This powerful technology makes it possible to obtain high-quality imaging of the object even in the presence of noise. Here, we introduce the GI method into quantum device evaluation in the time domain. We realized a proof-of-principle experiment to evaluate the temporal detection efficiency of a gated-mode single-photon avalanche detector (SPAD). The experimental results show that high-quality evaluation of temporal characteristics of the SPAD can be realized by the method of temporal GI (TGI). Our work indicates that the TGI method is an effective tool to monitor the temporal characteristics of quantum devices in real time and will bring a new perspective to the security evaluation of quantum communication.

We show how quantum entangled biphoton states can be used to realize ghost scattering, a nonlocal scheme to obtain scattering information of an unknown object through the correlation measurement of the scattering photons in two different optical paths. We present a framework to describe the biphoton ghost scattering process from the T-matrix formula of the scattering theory. We find the scattering information of a test object can be retrieved from either the test arm or the reference arm. By adjusting the biphoton states, the ghost scattering patterns may be varied from the scattering pattern of the object in the test arm to the object in the reference arm.