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

Journal of Optics

Acquisition of multiple photon pairs with an EMCCD camera

Eliot Bolduc, Daniele Faccio, Jonathan Leach

Published Apr 18, 2017• 19 citations
Publisher

Abstract

The detection and characterization of quantum states of light plays an important role in quantum science. Traditional methods use single-photon detectors, but these are generally limited to point measurements; consequently, multi-pixel devices are now being utilized in quantum measurements, especially in the field of quantum imaging. Here, we demonstrate the capability of an EMCCD camera to record multiple coincidence events originating from parametric downconversion where the mean photon number per pixel is much greater than unity. The multi-pixel nature of the camera enables us to record correlations ranging from to 10 000 coincidences per frame. This approach to quantum measurements provide mechanisms for recording quantum signatures for bright correlated photon sources.

DOI
10.1088/2040-8986/aa52d8

Related papers

Quantum imaging with a photon counting camera

Osian Wolley, Thomas Gregory, Sebastian M. J. Beer +2 more

Classical light sources emit a randomly-timed stream of individual photons, the spatial distribution of which can be detected with a camera to form an image. Quantum light sources, based on parametric down conversion, emit photons as correlated photon-pairs. The spatial correlations between the photons enables imaging systems where the preferential selection of photon-pairs allows for enhancements in the noise performance over what is possible using classical light sources. However, until now the technical challenge of measuring, and correlating both photons has led to system complexity. Here we show that a camera capable of resolving the number of individual photons in each pixel of the detector array can be used to record an image formed from these photon-pair events and hence achieve a greater contrast than possible using a classical light source. We achieve an enhancement in the ratio of two-photon events compared to one-photon events using spatially correlated SPDC light compared to uncorrelated illumination by a LED. These results indicate the potential advantages of using photon counting cameras in quantum imaging schemes and these advantages will further increase as the technology is developed. Operating in photon sparse regimes such systems have potential applications in low-light microscopy and covert imaging.

Scientific Reports•May 18, 2022•47 citations

Full field measurement of spatial correlated photon pairs with an EMCCD camera

M. Edgar, D. S. Tasca, Frauke Izdebski +5 more

The spatial correlations between the photon pairs produced by spontaneous parametric down conversion (SPDC) have been investigated in a number of different configurations over the last two decades (1). The high dimensionality of the transverse spatial degrees of freedom (DOF) of the photon pairs can be explored either by projections onto a discrete (infinite) basis, such as the LG modes, or by using a continuous basis defined by the transverse position or momentum of the photons. For instance, it has been shown that their transverse position and momentum display EPR-type correlations (2). Despite the continuous and unbounded nature of both these bases, the most common measurements to date have relied upon the scanning of a single avalanche photodiode or a very small number of individual detectors. This sequential scanning or small number of detectors negates any information capacity advantage in the use of spatial states. Recent years have seen a rapid advance in imaging technologies, particularly for low light levels. Of these technologies the highest quantum efficiency is achieved using electron multiplying CCDs (EMCCD). Developments in low noise EMCCD cameras suggest they are capable of greater than 80% quantum efficiencies and if operated in an ultra-low light environment whilst being maintained at low temperatures, can provide single photon sensitivity (3). EMCCDs have been used in measurements of sub-shot-noise correlations of intensity fluctuations (4, 5) as well as in intensity correlations measurements (6) in the far field of the photon pairs from SPDC. Here we report the observation of spatial correlations from SPDC using an EMCCD camera in both the image and far-field planes of the down conversion crystal. We pump a BBO crystal at 355nm with a few milli-Watts of optical power and use a simple lens system to relay the down-converted light to an EMCCD array which can be positioned in either the image plane or the far-field of the crystal. Our photon flux is around 1/100 per pixel, which approximately doubles the signal obtained when the light is blocked. We typically record 100,000 individual frames and then sum the auto-correlation of the individual frames. We observed intensity correlation and anti-correlation in the image and far-field planes, respectively. In both cases we make the correlations more visible by subtracting a background which is obtained as the average correlation obtained between successive frames. Using this approach we are able to visualize the strength of the correlations in both position and momentum, showing a variance product nearly one order of magnitude below the classical limit in both x and y directions.

•Jan 1, 2012•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

Measuring correlated photon pairs with an EMCCD camera

Jonathan Leach, Sangeeta Murugkar, M. Edgar +4 more

The multiple pixels and high quantum efficiency of EMCCD cameras make them an attractive technology for quantum optics. We use such a camera to measure correlations present in the two-photon field generated by parametric down-conversion.

International Conference on Quantum Information•Jan 1, 2011•0 citations

Quantum correlations measured with multi-pixel detectors

Frauke Izdebski

use of any of the information contained in it must acknowledge this thesis as the source of the quotation or information. This thesis investigates the measurement of spatial correlations of photon pairs gener-ated through spontaneous parametric down-conversion with single-photon sensitive multi-pixel detectors. A custom designed and fabricated 8×1 fibre array detector for time to position multi-plexing was characterised. This detector was then commissioned in an experiment measuring the spatial correlations of photon pairs in position, momentum and in-termediate bases. The fibre array measured eight positions simultaneously with one Single-Photon Avalanche Diode, which led to an eight-fold increase in the data ac-quisition rate compared to traditional experiments, where a single SPAD was scanned across the detection plane. To capture all of the emitted light, an electron-multiplying CCD (EMCCD) camera was used. The spatial correlations were measured for the first time in momentum and pos-

•Aug 1, 2013•0 citations

Examining the effectiveness of increasing EMCCD EM gain beyond standard manufacturer limits in determining photon pair correlations

Kieran A. Roberts, Thomas Gregory, Miles J. Padgett

Electron multiplying charge coupled device (EMCCD) cameras are widely used for single-photon detection in various quantum optics applications. For example, these EMCCD cameras have been extensively used to measure the position and momentum correlations between photon pairs produced by parametric down-conversion in the image and far-field planes of the down-conversion crystal, respectively. The camera's operating parameters are typically set to balance a high quantum efficiency while simultaneously maintaining a low number of erroneous photon detections, the latter being mainly attributable to clock-induced charge (CIC) events in the readout register. The visibility of the measured correlations is an indication of the quantum efficiency of detecting the photon pairs versus the prevalence of the unwanted CIC. In this work, we show that this correlation visibility can be enhanced by operating the EMCCD camera with the electron multiplying (EM) gain set well in excess of its standard operating conditions. This enhancement will be of interest to those using EMCCD detectors in quantum imaging, sensing and processing applications.

Optics Express•Jul 22, 2025•0 citations
The detection and characterization of quantum states of light plays an important role in quantum science. Traditional methods use single-photon detectors, but these are generally limited to point measurements; consequently, multi-pixel devices are now being utilized in quantum measurements, especially in the field of quantum imaging. Here, we demonstrate the capability of an EMCCD camera to record multiple coincidence events originating from parametric downconversion where the mean photon number per pixel is much greater than unity. The multi-pixel nature of the camera enables us to record correlations ranging from to 10 000 coincidences per frame. This approach to quantum measurements provide mechanisms for recording quantum signatures for bright correlated photon sources.
Classical light sources emit a randomly-timed stream of individual photons, the spatial distribution of which can be detected with a camera to form an image. Quantum light sources, based on parametric down conversion, emit photons as correlated photon-pairs. The spatial correlations between the photons enables imaging systems where the preferential selection of photon-pairs allows for enhancements in the noise performance over what is possible using classical light sources. However, until now the technical challenge of measuring, and correlating both photons has led to system complexity. Here we show that a camera capable of resolving the number of individual photons in each pixel of the detector array can be used to record an image formed from these photon-pair events and hence achieve a greater contrast than possible using a classical light source. We achieve an enhancement in the ratio of two-photon events compared to one-photon events using spatially correlated SPDC light compared to uncorrelated illumination by a LED. These results indicate the potential advantages of using photon counting cameras in quantum imaging schemes and these advantages will further increase as the technology is developed. Operating in photon sparse regimes such systems have potential applications in low-light microscopy and covert imaging.
The spatial correlations between the photon pairs produced by spontaneous parametric down conversion (SPDC) have been investigated in a number of different configurations over the last two decades (1). The high dimensionality of the transverse spatial degrees of freedom (DOF) of the photon pairs can be explored either by projections onto a discrete (infinite) basis, such as the LG modes, or by using a continuous basis defined by the transverse position or momentum of the photons. For instance, it has been shown that their transverse position and momentum display EPR-type correlations (2). Despite the continuous and unbounded nature of both these bases, the most common measurements to date have relied upon the scanning of a single avalanche photodiode or a very small number of individual detectors. This sequential scanning or small number of detectors negates any information capacity advantage in the use of spatial states. Recent years have seen a rapid advance in imaging technologies, particularly for low light levels. Of these technologies the highest quantum efficiency is achieved using electron multiplying CCDs (EMCCD). Developments in low noise EMCCD cameras suggest they are capable of greater than 80% quantum efficiencies and if operated in an ultra-low light environment whilst being maintained at low temperatures, can provide single photon sensitivity (3). EMCCDs have been used in measurements of sub-shot-noise correlations of intensity fluctuations (4, 5) as well as in intensity correlations measurements (6) in the far field of the photon pairs from SPDC. Here we report the observation of spatial correlations from SPDC using an EMCCD camera in both the image and far-field planes of the down conversion crystal. We pump a BBO crystal at 355nm with a few milli-Watts of optical power and use a simple lens system to relay the down-converted light to an EMCCD array which can be positioned in either the image plane or the far-field of the crystal. Our photon flux is around 1/100 per pixel, which approximately doubles the signal obtained when the light is blocked. We typically record 100,000 individual frames and then sum the auto-correlation of the individual frames. We observed intensity correlation and anti-correlation in the image and far-field planes, respectively. In both cases we make the correlations more visible by subtracting a background which is obtained as the average correlation obtained between successive frames. Using this approach we are able to visualize the strength of the correlations in both position and momentum, showing a variance product nearly one order of magnitude below the classical limit in both x and y directions.
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.
use of any of the information contained in it must acknowledge this thesis as the source of the quotation or information. This thesis investigates the measurement of spatial correlations of photon pairs gener-ated through spontaneous parametric down-conversion with single-photon sensitive multi-pixel detectors. A custom designed and fabricated 8×1 fibre array detector for time to position multi-plexing was characterised. This detector was then commissioned in an experiment measuring the spatial correlations of photon pairs in position, momentum and in-termediate bases. The fibre array measured eight positions simultaneously with one Single-Photon Avalanche Diode, which led to an eight-fold increase in the data ac-quisition rate compared to traditional experiments, where a single SPAD was scanned across the detection plane. To capture all of the emitted light, an electron-multiplying CCD (EMCCD) camera was used. The spatial correlations were measured for the first time in momentum and pos-
Electron multiplying charge coupled device (EMCCD) cameras are widely used for single-photon detection in various quantum optics applications. For example, these EMCCD cameras have been extensively used to measure the position and momentum correlations between photon pairs produced by parametric down-conversion in the image and far-field planes of the down-conversion crystal, respectively. The camera's operating parameters are typically set to balance a high quantum efficiency while simultaneously maintaining a low number of erroneous photon detections, the latter being mainly attributable to clock-induced charge (CIC) events in the readout register. The visibility of the measured correlations is an indication of the quantum efficiency of detecting the photon pairs versus the prevalence of the unwanted CIC. In this work, we show that this correlation visibility can be enhanced by operating the EMCCD camera with the electron multiplying (EM) gain set well in excess of its standard operating conditions. This enhancement will be of interest to those using EMCCD detectors in quantum imaging, sensing and processing applications.