Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Light Advanced Manufacturing

Seeing clearly with entangled biphotons

Lixiang Chen, Xiaodong Qiu

Published Jan 1, 2026• 0 citations
Publisher

Abstract

Position-correlated biphoton Shack-Hartmann wavefront sensing is proposed and experimentally demonstrated.Based on this approach, the biphoton correlation propagating through phase turbulence can be measured and corrected, thus enabling adaptive quantum imaging against phase disturbances with only a single-shot measurement.
DOI
10.37188/lam.2026.005

Related papers

Position-correlated biphoton wavefront sensing for quantum adaptive imaging

Yi Zheng, Zhao-Di Liu, Jian‐Shun Tang +3 more

Quantum imaging with spatially entangled photons offers advantages such as enhanced spatial resolution, robustness against noise, and counterintuitive phenomena, while a biphoton spatial aberration generally degrades its performance. Biphoton aberration correction has been achieved by using classical beams to detect the aberration source or scanning the correction phase on biphotons if the source is unreachable. Here, a new method named position-correlated biphoton Shack-Hartmann wavefront sensing is introduced, where the phase pattern added on photon pairs with a strong position correlation is reconstructed from their position centroid distribution at the back focal plane of a microlens array. Experimentally, biphoton phase measurement and adaptive imaging against the disturbance of a plastic film are demonstrated. This single-shot method is a more direct and efficient approach toward quantum adaptive optics, suitable for integration into quantum microscopy, remote imaging, and communication.

arXiv:2504.21573•Light Science & Applications•Sep 8, 2025•8 citations

Characterizing Biphoton Spatial Wave Function Dynamics with Quantum Wavefront Sensing

Yi Zheng, Zhao‐Di Liu, Rui-Heng Miao +6 more

With an extremely high dimensionality, the spatial degree of freedom of entangled photons is a key tool for quantum foundation and applied quantum techniques. To fully utilize the feature, the essential task is to experimentally characterize the multiphoton spatial wave function including the entangled amplitude and phase information at different evolutionary stages. However, there is no effective method to measure it. Quantum state tomography is costly, and quantum holography requires additional references. Here, we introduce quantum Shack-Hartmann wavefront sensing to perform efficient and reference-free measurement of the biphoton spatial wave function. The joint probability distribution of photon pairs at the back focal plane of a microlens array is measured and used for amplitude extraction and phase reconstruction. In the experiment, we observe that the biphoton amplitude correlation becomes weak while phase correlation shows up during free-space propagation. Our work is a crucial step in quantum physical and adaptive optics and paves the way for characterizing quantum optical fields with high-order correlations or topological patterns.

arXiv:2406.04973•Physical Review Letters•Jul 16, 2024•13 citations

Adaptive optics for single photons with parametrically varied emulated turbulence

Robert J. Von-Holle, Keith A. Wyman, Anil K. Patnaik

Long-range quantum communication requires sending qubits, usually photonic cubits, over long distances through free space. Photons propagating through free space encounter optical turbulence, causing scattering and entanglement degradation. In recent decades, adaptive optics has been used to correct imaging errors introduced by turbulence. An atmospheric turbulence simulator has been constructed to measure the effect of optical turbulence on single photon propagation, and an adaptive optics system has been incorporated. The turbulence simulator uses two rotating phase plates to emulate the effects of random dispersive media and two afocal systems to scale long propagation distances down to lengths realizable in a laboratory. The adaptive optics system consists of a Shack-Hartman wavefront sensor used to measure wavefront error, and a deformable mirror used to correct this error. The use of adaptive optics allows us to correct wavefront errors introduced by turbulence. Adding an adaptive optics system into this simulator facilitates more robust characterization of the strength of the simulated turbulence, as well as correction of some of the negative effects the turbulence introduces. This presentation will discuss the effects of turbulence on single photon propagation when an adaptive optics system is used and how these results compare to previously measurements taken without the use of adaptive optics, allowing us to quantify the improvement adaptive optics introduces.

Quantum Computing, Communication, and Simulation•Jan 24, 2025•0 citations

Adaptive-Optics Enhanced Distribution of Entangled Photons over Turbulent Free-Space Optical Channels

Vijay Nafria, Chaohan Cui, Ivan B. Djordjević +1 more

We experimentally demonstrate using of adaptive optics to mitigate atmospheric turbulence effects on the distribution of entangled photons over free-space optical links and provide significantly improved photon-counting rates and biphoton correlations.

Conference on Lasers and Electro-Optics•Jan 1, 2021•2 citations

Tracking phase entanglement during propagation of down-converted photons

Rounak Chatterjee, Vikas S. Bhat, Kiran Bajar +1 more

High-dimensional entanglement in the form of transverse spatial correlation between a pair of photons generated via spontaneous parametric downconversion is not only a valuable resource in many academic and real-life applications but also provides access to several intriguing quantum phenomena. One such non-intuitive phenomenon is phase entanglement, in which the biphoton state is correlated in the complex phase of its wavefunction. This state, which emerges during the propagation of the biphoton wavefunction, exhibits neither position nor momentum correlation, yet retains full entanglement. In this work, we experimentally explore this state in two distinct ways. The first is by tracking the vanishing spatial photon number correlation over propagation distances lying in $\left[0,\infty\right)$, folded into a finite range using single-lens imaging. These observations show excellent agreement with our theoretical predictions based on the Double Gaussian (DG) approximation of the biphoton state. The second approach involves performing a two-photon interference experiment using a double slit and this state, which reveals the correlated phase front. We show, both theoretically and experimentally, that the observed two-photon interference structure is markedly different from that produced by position-correlated photons, as confirmed by computing the joint probability distribution of photons (JPD) and related metrics. Such interference using phase-entangled light has not been attempted before and opens avenues for advanced experiments and applications in the field of spatial entanglement.

arXiv:2505.17906•Physical Review Applied•Jul 14, 2025•3 citations

Adaptive Optics Control of the Propagation of Biphoton Wavepacket

Mattia Minozzi, Stefano Bonora, Alexander V. Sergienko +2 more

Entangled photon pairs are generated with optimal pump wavefront to achieve a desirable free-space propagation. The optimization exploits a closed loop including a deformable mirror, the nonlinear crystal, the propagation line and the single-photon coincidences.

Imaging and Applied Optics•Jan 1, 2013•1 citation
Quantum imaging with spatially entangled photons offers advantages such as enhanced spatial resolution, robustness against noise, and counterintuitive phenomena, while a biphoton spatial aberration generally degrades its performance. Biphoton aberration correction has been achieved by using classical beams to detect the aberration source or scanning the correction phase on biphotons if the source is unreachable. Here, a new method named position-correlated biphoton Shack-Hartmann wavefront sensing is introduced, where the phase pattern added on photon pairs with a strong position correlation is reconstructed from their position centroid distribution at the back focal plane of a microlens array. Experimentally, biphoton phase measurement and adaptive imaging against the disturbance of a plastic film are demonstrated. This single-shot method is a more direct and efficient approach toward quantum adaptive optics, suitable for integration into quantum microscopy, remote imaging, and communication.
With an extremely high dimensionality, the spatial degree of freedom of entangled photons is a key tool for quantum foundation and applied quantum techniques. To fully utilize the feature, the essential task is to experimentally characterize the multiphoton spatial wave function including the entangled amplitude and phase information at different evolutionary stages. However, there is no effective method to measure it. Quantum state tomography is costly, and quantum holography requires additional references. Here, we introduce quantum Shack-Hartmann wavefront sensing to perform efficient and reference-free measurement of the biphoton spatial wave function. The joint probability distribution of photon pairs at the back focal plane of a microlens array is measured and used for amplitude extraction and phase reconstruction. In the experiment, we observe that the biphoton amplitude correlation becomes weak while phase correlation shows up during free-space propagation. Our work is a crucial step in quantum physical and adaptive optics and paves the way for characterizing quantum optical fields with high-order correlations or topological patterns.
Long-range quantum communication requires sending qubits, usually photonic cubits, over long distances through free space. Photons propagating through free space encounter optical turbulence, causing scattering and entanglement degradation. In recent decades, adaptive optics has been used to correct imaging errors introduced by turbulence. An atmospheric turbulence simulator has been constructed to measure the effect of optical turbulence on single photon propagation, and an adaptive optics system has been incorporated. The turbulence simulator uses two rotating phase plates to emulate the effects of random dispersive media and two afocal systems to scale long propagation distances down to lengths realizable in a laboratory. The adaptive optics system consists of a Shack-Hartman wavefront sensor used to measure wavefront error, and a deformable mirror used to correct this error. The use of adaptive optics allows us to correct wavefront errors introduced by turbulence. Adding an adaptive optics system into this simulator facilitates more robust characterization of the strength of the simulated turbulence, as well as correction of some of the negative effects the turbulence introduces. This presentation will discuss the effects of turbulence on single photon propagation when an adaptive optics system is used and how these results compare to previously measurements taken without the use of adaptive optics, allowing us to quantify the improvement adaptive optics introduces.
High-dimensional entanglement in the form of transverse spatial correlation between a pair of photons generated via spontaneous parametric downconversion is not only a valuable resource in many academic and real-life applications but also provides access to several intriguing quantum phenomena. One such non-intuitive phenomenon is phase entanglement, in which the biphoton state is correlated in the complex phase of its wavefunction. This state, which emerges during the propagation of the biphoton wavefunction, exhibits neither position nor momentum correlation, yet retains full entanglement. In this work, we experimentally explore this state in two distinct ways. The first is by tracking the vanishing spatial photon number correlation over propagation distances lying in [0,∞)\left[0,\infty\right)[0,∞), folded into a finite range using single-lens imaging. These observations show excellent agreement with our theoretical predictions based on the Double Gaussian (DG) approximation of the biphoton state. The second approach involves performing a two-photon interference experiment using a double slit and this state, which reveals the correlated phase front. We show, both theoretically and experimentally, that the observed two-photon interference structure is markedly different from that produced by position-correlated photons, as confirmed by computing the joint probability distribution of photons (JPD) and related metrics. Such interference using phase-entangled light has not been attempted before and opens avenues for advanced experiments and applications in the field of spatial entanglement.