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

APL Photonics

Entanglement distillation by Hong-Ou-Mandel interference with orbital angular momentum states

Bienvenu I. Ndagano, Andrew Forbes

Published Jan 1, 2019• 19 citations
Publisher

Abstract

Entanglement is an invaluable resource to various quantum communication, metrology, and computing processes. In particular, spatial entanglement has become topical, owing to its wider Hilbert space that allows photons to carry more information. However, spatial entanglement is susceptible to decay in the presence of external perturbations such as atmospheric turbulence. Here we show theoretically and experimentally that in a weak turbulence regime, maximally entangled states can be distilled through quantum interference. We generated entangled photons by spontaneous parametric down-conversion, with one photon in the entangled pairs being sent through a turbulent channel. We recombined the paths of the two photons at a beam-splitter in a Hong-Ou-Mandel interference setup and measured in coincidence, using spatial filters, the spatial correlations between photons in the output ports of the beam-splitter. We performed a state tomography and show that, from an ensemble of pure states with very low levels of entanglement, we distil entangled states with fidelities F ≥ 0.90 with respect to the singlet Bell state.

DOI
10.1063/1.5079970

Related papers

Turbulence and the Hong-Ou-Mandel effect

Shashi Prabhakar, Chemist M. Mabena, Thomas Konrad +1 more

The effect of a decoherence channel, such as a turbulent atmosphere, on the second-order quantum interference in the Hong-Ou-Mandel (HOM) effect is investigated. The investigation includes both theoretical analyses and an experimental implementation of the process. In our experiment, entangled input states are prepared with spontaneous parametric down-conversion. The atmospheric turbulence is modeled as a single-phase screen and simulated with spatial light modulators according to the theory of Kolmogorov. We find both theoretically and experimentally that the HOM dip is unaffected when only one of the photons passes through turbulence. When both photons pass through turbulence, the HOM interference is only slightly affected by the scintillation. The reasons behind these findings and their consequences for HOM-based teleportation are discussed.

arXiv:1709.02670•Physical Review A•Jan 23, 2018•11 citations

Experimental demonstration of free-space two-photon interference

Shuang-Lin Li, Hai-Lin Yong, Yu-Huai Li +9 more

Quantum interference plays an essential role in understanding the concepts of quantum physics. Moreover, the interference of photons is indispensable for large-scale quantum information processing. With the development of quantum networks, interference of photons transmitted through long-distance fiber channels has been widely implemented. However, quantum interference of photons using free-space channels is still scarce, mainly due to atmospheric turbulence. Here, we report an experimental demonstration of Hong-Ou-Mandel interference with photons transmitted by free-space channels. Two typical photon sources, i.e., correlated photon pairs generated in spontaneous parametric down conversion (SPDC) process and weak coherent states, are employed. A visibility of 0.744 ± 0.013 is observed by interfering with two photons generated in the SPDC process, exceeding the classical limit of 0.5. Our results demonstrate that the quantum property of photons remains even after transmission through unstable free-space channels, indicating the feasibility and potential application of free-space-based quantum interference in quantum information processing.

Optics Express•Feb 11, 2022•2 citations

Wavefront division quantum interferometry

Mahdi Eshaghi, Ruitao Wu, Erwan Baleine +1 more

We investigate the use of a spatially distributed beam of entangled photons for applications of wavefront division interferometry. Using a fiber-based spontaneous parametric down conversion process, which redirect the signal and idler into a common single-mode fiber, we generate a Gaussian beam of colinear entangled photons randomly distributed in space. Coincidence measurements carried by wavefront division demonstrate quantum interference patterns, including classical single photon fringes, two-photon interferences and the Hong-Ou-Mandel effect. Our results are relevant for detecting transverse variations in the statistical properties of weak turbulence.

Quantum Communications and Quantum Imaging•Oct 3, 2023•0 citations

Parameter dependence of the decoherence of orbital angular momentum entanglement in atmospheric turbulence

Alpha Hamadou Ibrahim, Filippus Stefanus Roux, Thomas Konrad

The orbital angular momentum (OAM) state of light can potentially be used to implement higher dimensional entangled systems for quantum communication. Unfortunately, optical fibers in use today support only modes with zero OAM values. Free-space quantum communication is an alternative to traditional way of communicating through optical fibers. However the refractive index fluctuation of the atmosphere gives rise to random phase aberrations on a propagating optical beam. To transmit quantum information successfully through a free-space optical channel, one needs to understand how atmospheric turbulence influences quantum entanglement. Here, we present a numerical study of the evolution of quantum entanglement between a pair of qubits. The qubits consist of photons entangled in the OAM basis. The photons propagate in a turbulent atmosphere modeled by a series of consecutive phase screens based on the Kolmogorov theory of turbulence. Maximally entangled initial states are considered, and the concurrence is used as a measure of entanglement. We show how the evolution of entanglement is influenced by various parameters such as the beam waist, the strength of the turbulence and the wavelength of the beam. We restricted our analysis to the OAM values l = ±1 and we compared our results to previous work.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Sep 1, 2011•0 citations

Spatial entanglement and state engineering via four-photon Hong–Ou–Mandel interference

Alessandro Ferreri, Vahid Ansari, Benjamin Brecht +2 more

Abstract The phenomenon of entanglement is the basis of quantum information and quantum communication processes. Entangled systems with a large number of photons are of great interest at present because they provide a platform for streaming technologies based on photonics. In this paper we present a device which operates with four-photons and based on the Hong–Ou–Mandel interference. The presented device allows to maximize the degree of spatial entanglement and generate the highly entangled four-dimensional Bell states. Furthermore, the use of the interferometer in different regimes leads to fast interference fringes in the coincidence probability with period of oscillations twice smaller than the pump wavelength. We have a good agreement between theoretical simulations and experimental results.

arXiv:2007.10056•Quantum Science and Technology•Sep 1, 2020•3 citations

Characterization and mitigation of information loss in a six-state quantum-key-distribution protocol with spatial modes of light through turbulence

Bienvenu I. Ndagano, Andrew Forbes

Quantum communication with structured photons is topical, owing to the multidimensional state space of spatial modes. However, spatial modes are fragile and their quality degrades when perturbed in traditional communication media such as free-space and optical fibers. Here, we illustrate the effects of atmospheric turbulence on a six-state quantum-key-distribution protocol with orbital angular momentum (OAM) modes. We experimentally characterize the fidelity decay as a function of turbulence strength, showing a concomitant decrease with increasing perturbation, and consider the influence of both mode order and mode size, showing that OAM modes with higher helicity are more resilient to turbulence for this protocol. We outline two approaches to mitigate the photon information loss. In the first, we show that by postselecting on a high-dimensional subspace at the detection side, we can recover information contained in the scattered modes. In the second, we measure the channel operator by means of classically entangled light and mitigate errors on the quantum state through entanglement concentration by means of one-party Procrustean filtering. The tools we provide here will be beneficial for realizing more robust quantum communication with OAM modes of light.

Physical Review A•Dec 26, 2018•22 citations
Entanglement is an invaluable resource to various quantum communication, metrology, and computing processes. In particular, spatial entanglement has become topical, owing to its wider Hilbert space that allows photons to carry more information. However, spatial entanglement is susceptible to decay in the presence of external perturbations such as atmospheric turbulence. Here we show theoretically and experimentally that in a weak turbulence regime, maximally entangled states can be distilled through quantum interference. We generated entangled photons by spontaneous parametric down-conversion, with one photon in the entangled pairs being sent through a turbulent channel. We recombined the paths of the two photons at a beam-splitter in a Hong-Ou-Mandel interference setup and measured in coincidence, using spatial filters, the spatial correlations between photons in the output ports of the beam-splitter. We performed a state tomography and show that, from an ensemble of pure states with very low levels of entanglement, we distil entangled states with fidelities F ≥ 0.90 with respect to the singlet Bell state.
The effect of a decoherence channel, such as a turbulent atmosphere, on the second-order quantum interference in the Hong-Ou-Mandel (HOM) effect is investigated. The investigation includes both theoretical analyses and an experimental implementation of the process. In our experiment, entangled input states are prepared with spontaneous parametric down-conversion. The atmospheric turbulence is modeled as a single-phase screen and simulated with spatial light modulators according to the theory of Kolmogorov. We find both theoretically and experimentally that the HOM dip is unaffected when only one of the photons passes through turbulence. When both photons pass through turbulence, the HOM interference is only slightly affected by the scintillation. The reasons behind these findings and their consequences for HOM-based teleportation are discussed.
Quantum interference plays an essential role in understanding the concepts of quantum physics. Moreover, the interference of photons is indispensable for large-scale quantum information processing. With the development of quantum networks, interference of photons transmitted through long-distance fiber channels has been widely implemented. However, quantum interference of photons using free-space channels is still scarce, mainly due to atmospheric turbulence. Here, we report an experimental demonstration of Hong-Ou-Mandel interference with photons transmitted by free-space channels. Two typical photon sources, i.e., correlated photon pairs generated in spontaneous parametric down conversion (SPDC) process and weak coherent states, are employed. A visibility of 0.744 ± 0.013 is observed by interfering with two photons generated in the SPDC process, exceeding the classical limit of 0.5. Our results demonstrate that the quantum property of photons remains even after transmission through unstable free-space channels, indicating the feasibility and potential application of free-space-based quantum interference in quantum information processing.
We investigate the use of a spatially distributed beam of entangled photons for applications of wavefront division interferometry. Using a fiber-based spontaneous parametric down conversion process, which redirect the signal and idler into a common single-mode fiber, we generate a Gaussian beam of colinear entangled photons randomly distributed in space. Coincidence measurements carried by wavefront division demonstrate quantum interference patterns, including classical single photon fringes, two-photon interferences and the Hong-Ou-Mandel effect. Our results are relevant for detecting transverse variations in the statistical properties of weak turbulence.
The orbital angular momentum (OAM) state of light can potentially be used to implement higher dimensional entangled systems for quantum communication. Unfortunately, optical fibers in use today support only modes with zero OAM values. Free-space quantum communication is an alternative to traditional way of communicating through optical fibers. However the refractive index fluctuation of the atmosphere gives rise to random phase aberrations on a propagating optical beam. To transmit quantum information successfully through a free-space optical channel, one needs to understand how atmospheric turbulence influences quantum entanglement. Here, we present a numerical study of the evolution of quantum entanglement between a pair of qubits. The qubits consist of photons entangled in the OAM basis. The photons propagate in a turbulent atmosphere modeled by a series of consecutive phase screens based on the Kolmogorov theory of turbulence. Maximally entangled initial states are considered, and the concurrence is used as a measure of entanglement. We show how the evolution of entanglement is influenced by various parameters such as the beam waist, the strength of the turbulence and the wavelength of the beam. We restricted our analysis to the OAM values l = ±1 and we compared our results to previous work.
Abstract The phenomenon of entanglement is the basis of quantum information and quantum communication processes. Entangled systems with a large number of photons are of great interest at present because they provide a platform for streaming technologies based on photonics. In this paper we present a device which operates with four-photons and based on the Hong–Ou–Mandel interference. The presented device allows to maximize the degree of spatial entanglement and generate the highly entangled four-dimensional Bell states. Furthermore, the use of the interferometer in different regimes leads to fast interference fringes in the coincidence probability with period of oscillations twice smaller than the pump wavelength. We have a good agreement between theoretical simulations and experimental results.
Quantum communication with structured photons is topical, owing to the multidimensional state space of spatial modes. However, spatial modes are fragile and their quality degrades when perturbed in traditional communication media such as free-space and optical fibers. Here, we illustrate the effects of atmospheric turbulence on a six-state quantum-key-distribution protocol with orbital angular momentum (OAM) modes. We experimentally characterize the fidelity decay as a function of turbulence strength, showing a concomitant decrease with increasing perturbation, and consider the influence of both mode order and mode size, showing that OAM modes with higher helicity are more resilient to turbulence for this protocol. We outline two approaches to mitigate the photon information loss. In the first, we show that by postselecting on a high-dimensional subspace at the detection side, we can recover information contained in the scattered modes. In the second, we measure the channel operator by means of classically entangled light and mitigate errors on the quantum state through entanglement concentration by means of one-party Procrustean filtering. The tools we provide here will be beneficial for realizing more robust quantum communication with OAM modes of light.