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

arXiv:1204.0990 · Physical Review A

Realization of the purely spatial Einstein-Podolsky-Rosen paradox in full-field images of spontaneous parametric down-conversion

Paul‐Antoine Moreau, Joé Mougin-Sisini, F. Devaux, Éric Lantz

Published Jul 3, 2012• 89 citations
arXivHTMLPDF

Abstract

We demonstrate Einstein-Podolsky-Rosen (EPR) entanglement by detecting purely spatial quantum correlations in the near and far fields of spontaneous parametric down-conversion generated in a type-2 beta barium borate crystal. Full-field imaging is performed in the photon-counting regime with an electron-multiplying CCD camera. The data are used without any postselection, and we obtain a violation of Heisenberg inequalities with inferred quantities taking into account all the biphoton pairs in both the near and far fields by integration on the entire two-dimensional transverse planes. This ensures a rigorous demonstration of the EPR paradox in its original position-momentum form.

DOI
10.1103/physreva.86.010101

Related papers

2-D measurement of the spatial Einstein-Podolsky-Rosen paradox in images of type II spontaneous parametric down conversion

Éric Lantz, Paul‐Antoine Moreau, Joé Mougin-Sisini +1 more

We demonstrate EPR entanglement by detecting purely spatial quantum correlations in the near and far-field of spontaneous parametric down conversion generated in a type II BBO crystal. Full field imaging is performed in the photon counting regime with an electron-multiplying CCD (EMCCD) camera. The data are used without any post-selection and we obtain a violation of Heisenberg inequalities with inferred quantities in both transverse dimensions taking into account all the biphoton pairs in both the near and far field, by integration on the entire two dimensional transverse planes. This ensures a rigorous demonstration of the EPR paradox in its original position-momentum form.

Frontiers in Optics•Jan 1, 2012•0 citations

2-D measurement of the spatial Einstein-Podolsky-Rosen paradox in pairs of images of type II spontaneous parametric down conversion

Paul‐Antoine Moreau, F. Devaux, Éric Lantz

We demonstrate EPR entanglement by detecting with two electron-multiplying CCD (EMCCD) cameras spatial quantum correlations in the near and far-field of type II spontaneous parametric down conversion. The degree of paradox appears as one among the highest ever reported.

Research in Optical Sciences•Jan 1, 2014•0 citations

Einstein-Podolsky-Rosen Paradox in Twin Images

Paul‐Antoine Moreau, F. Devaux, Éric Lantz

Spatially entangled twin photons provide both promising resources for modern quantum information protocols, because of the high dimensionality of transverse entanglement, and a test of the Einstein-Podolsky-Rosen paradox in its original form of position versus impulsion. Usually, photons in temporal coincidence are selected and their positions recorded, resulting in a priori assumptions on their spatiotemporal behavior. In this Letter, we record, on two separate electron-multiplying charge coupled devices cameras, twin images of the entire flux of spontaneous down-conversion. This ensures a strict equivalence between the subsystems corresponding to the detection of either position (image or near-field plane) or momentum (Fourier or far-field plane). We report the highest degree of paradox ever reported and show that this degree corresponds to the number of independent degrees of freedom, or resolution cells, of the images.

arXiv:1404.3028•Physical Review Letters•Oct 14, 2014•104 citations

Imaging Walk-Off Driven Distortions in EPR Photon Pair Correlations

Christian Howard, Roohollah Ghobadi, Nazanin Dehghan +2 more

Spontaneous parametric down-conversion is the primary source of position-correlated and momentum-anticorrelated photon pairs that form the canonical Einstein-Podolsky-Rosen (EPR) state. Their transverse spatial correlations are usually analyzed within the thin-crystal approximation, where the two-photon wavefunction is assumed to factorize into independent functions of the sum and difference coordinates. In practice, however, birefringence-induced transverse walk-off breaks this factorization and couples these degrees of freedom. Here, we show that this coupling persists even for nominally thin crystals once the free-space propagation of the joint spatial intensity is taken into account. This sum-difference coordinate coupling leads to a distinctive tapering of the transverse correlations near the crystal image plane-an effect that standard factorized models cannot capture. Numerical simulations and experimental data clearly confirm this novel behavior. Our findings provide a more complete description of photon-pair generation in birefringent nonlinear media and clarify fundamental limits on spatially resolved quantum imaging and spatial-mode quantum information processing with EPR states.

quant-pharXiv:2512.12423•Optics Express•Dec 16, 2025•0 citations

Imaging walk-off-driven distortions in EPR photon-pair correlations.

Christian Howard, Roohollah Ghobadi, Nazanin Dehghan +2 more

Spontaneous parametric down-conversion is the primary source of position-correlated and momentum-anti-correlated photon pairs that form the canonical Einstein-Podolsky-Rosen (EPR) state. Their transverse spatial correlations are usually analyzed within the thin-crystal approximation, where the two-photon wavefunction is assumed to factorize into independent functions of the sum and difference coordinates. In practice, however, birefringence-induced transverse walk-off breaks this factorization and couples these degrees of freedom. Here, we show that this coupling persists even for nominally thin crystals once the free-space propagation of the joint spatial intensity is taken into account. This sum-difference coordinate coupling leads to a distinctive tapering of the transverse correlations near the crystal image plane - an effect that standard factorized models cannot capture. Numerical simulations and experimental data clearly confirm this novel behavior. Our findings provide a more complete description of photon-pair generation in birefringent nonlinear media and clarify fundamental limits on spatially resolved quantum imaging and spatial-mode quantum information processing with EPR states.

•Jun 15, 2026•0 citations

Imaging high-dimensional spatial entanglement with a camera

M. Edgar, D. S. Tasca, Frauke Izdebski +6 more

The light produced by parametric down-conversion shows strong spatial entanglement that leads to violations of EPR criteria for separability. Historically, such studies have been performed by scanning a single-element, single-photon detector across a detection plane. Here we show that modern electron-multiplying charge-coupled device cameras can measure correlations in both position and momentum across a multi-pixel field of view. This capability allows us to observe entanglement of around 2,500 spatial states and demonstrate Einstein–Podolsky–Rosen type correlations by more than two orders of magnitude. More generally, our work shows that cameras can lead to important new capabilities in quantum optics and quantum information science. Measuring the entanglement between down-converted photons is central to many quantum optical experiments, and is normally performed by scanning detectors stepwise across a plane. Edgaret al. use a CCD camera to measure the entire entangled light field, finding strong correlations in position and momentum.

arXiv:1204.1293•Nature Communications•Aug 7, 2012•279 citations
We demonstrate Einstein-Podolsky-Rosen (EPR) entanglement by detecting purely spatial quantum correlations in the near and far fields of spontaneous parametric down-conversion generated in a type-2 beta barium borate crystal. Full-field imaging is performed in the photon-counting regime with an electron-multiplying CCD camera. The data are used without any postselection, and we obtain a violation of Heisenberg inequalities with inferred quantities taking into account all the biphoton pairs in both the near and far fields by integration on the entire two-dimensional transverse planes. This ensures a rigorous demonstration of the EPR paradox in its original position-momentum form.
We demonstrate EPR entanglement by detecting purely spatial quantum correlations in the near and far-field of spontaneous parametric down conversion generated in a type II BBO crystal. Full field imaging is performed in the photon counting regime with an electron-multiplying CCD (EMCCD) camera. The data are used without any post-selection and we obtain a violation of Heisenberg inequalities with inferred quantities in both transverse dimensions taking into account all the biphoton pairs in both the near and far field, by integration on the entire two dimensional transverse planes. This ensures a rigorous demonstration of the EPR paradox in its original position-momentum form.
Spatially entangled twin photons provide both promising resources for modern quantum information protocols, because of the high dimensionality of transverse entanglement, and a test of the Einstein-Podolsky-Rosen paradox in its original form of position versus impulsion. Usually, photons in temporal coincidence are selected and their positions recorded, resulting in a priori assumptions on their spatiotemporal behavior. In this Letter, we record, on two separate electron-multiplying charge coupled devices cameras, twin images of the entire flux of spontaneous down-conversion. This ensures a strict equivalence between the subsystems corresponding to the detection of either position (image or near-field plane) or momentum (Fourier or far-field plane). We report the highest degree of paradox ever reported and show that this degree corresponds to the number of independent degrees of freedom, or resolution cells, of the images.
Spontaneous parametric down-conversion is the primary source of position-correlated and momentum-anticorrelated photon pairs that form the canonical Einstein-Podolsky-Rosen (EPR) state. Their transverse spatial correlations are usually analyzed within the thin-crystal approximation, where the two-photon wavefunction is assumed to factorize into independent functions of the sum and difference coordinates. In practice, however, birefringence-induced transverse walk-off breaks this factorization and couples these degrees of freedom. Here, we show that this coupling persists even for nominally thin crystals once the free-space propagation of the joint spatial intensity is taken into account. This sum-difference coordinate coupling leads to a distinctive tapering of the transverse correlations near the crystal image plane-an effect that standard factorized models cannot capture. Numerical simulations and experimental data clearly confirm this novel behavior. Our findings provide a more complete description of photon-pair generation in birefringent nonlinear media and clarify fundamental limits on spatially resolved quantum imaging and spatial-mode quantum information processing with EPR states.
Spontaneous parametric down-conversion is the primary source of position-correlated and momentum-anti-correlated photon pairs that form the canonical Einstein-Podolsky-Rosen (EPR) state. Their transverse spatial correlations are usually analyzed within the thin-crystal approximation, where the two-photon wavefunction is assumed to factorize into independent functions of the sum and difference coordinates. In practice, however, birefringence-induced transverse walk-off breaks this factorization and couples these degrees of freedom. Here, we show that this coupling persists even for nominally thin crystals once the free-space propagation of the joint spatial intensity is taken into account. This sum-difference coordinate coupling leads to a distinctive tapering of the transverse correlations near the crystal image plane - an effect that standard factorized models cannot capture. Numerical simulations and experimental data clearly confirm this novel behavior. Our findings provide a more complete description of photon-pair generation in birefringent nonlinear media and clarify fundamental limits on spatially resolved quantum imaging and spatial-mode quantum information processing with EPR states.
The light produced by parametric down-conversion shows strong spatial entanglement that leads to violations of EPR criteria for separability. Historically, such studies have been performed by scanning a single-element, single-photon detector across a detection plane. Here we show that modern electron-multiplying charge-coupled device cameras can measure correlations in both position and momentum across a multi-pixel field of view. This capability allows us to observe entanglement of around 2,500 spatial states and demonstrate Einstein–Podolsky–Rosen type correlations by more than two orders of magnitude. More generally, our work shows that cameras can lead to important new capabilities in quantum optics and quantum information science. Measuring the entanglement between down-converted photons is central to many quantum optical experiments, and is normally performed by scanning detectors stepwise across a plane. Edgaret al. use a CCD camera to measure the entire entangled light field, finding strong correlations in position and momentum.