© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

arXiv:1611.10237 · Journal of Optics

Biphoton transmission through non-unitary objects

Matthew Reichert, Hugo Defienne, Xiaohang Sun, Jason W Fleischer

Published Mar 16, 2017• 13 citations

Abstract

Abstract Losses should be accounted for in a complete description of quantum imaging systems, and yet they are often treated as undesirable and largely neglected. In conventional quantum imaging, images are built up by coincidence detection of spatially entangled photon pairs (biphotons) transmitted through an object. However, as real objects are non-unitary (absorptive), part of the transmitted state contains only a single photon, which is overlooked in traditional coincidence measurements. The single-photon part has a drastically different spatial distribution than the two-photon part. It contains information about both the object, and, remarkably, the spatial entanglement properties of the incident biphotons. Here, we image the one- and two-photon parts of the transmitted state using an electron multiplying CCD array, treating it both as a traditional camera and as a massively parallel coincidence counting apparatus, and demonstrate agreement with theoretical predictions of non-unitary quantum optics. This work may prove useful for photon-number imaging and may lead to techniques for entanglement characterization that do not require coincidence measurements.

DOI: 10.1088/2040-8986/aa6175

Related papers

Quantum imaging and spatial entanglement characterization with an EMCCD camera

Matthew C. Reichert, Hugo Defienne, Xiaohang Sun +1 more

We utilize a single-photon sensitive electron multiplying CCD camera as a massively parallel coincidence counting apparatus to study spatial entanglement of photon pairs. This allows rapid measurement of transverse spatial entanglement in a fraction of the time required with traditional point-scanning techniques. We apply this technique to quantum experiments on entangled photon pairs: characterization of the evolution of entanglement upon propagation, and measurement of one- and two-photon portions of the state transmitted through non-unitary (lossy) objects, and quantum phase imaging.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 8, 2017•0 citations

Quantum Imaging of Non-Unitary Objects with Spatially Entangled Photon Pairs

Matthew C. Reichert, Hugo Defienne, Xiaohang Sun +1 more

We image one- and two-photon parts of the state of entangled photon pairs transmitted through lossy objects using an EMCCD camera and demonstrate that the one-photon intensity contains information on the degree of spatial entanglement.

Imaging and Applied Optics•Jan 1, 2017•0 citations

Quantum Phase Imaging using Spatial Entanglement

Chien-Hung Lu, Matthew C. Reichert, Sun, Xiaohang +1 more

Entangled photons have the remarkable ability to be more sensitive to signal and less sensitive to noise than classical light. Joint photons can sample an object collectively, resulting in faster phase accumulation and higher spatial resolution, while common components of noise can be subtracted. Even more, they can accomplish this while physically separate, due to the nonlocal properties of quantum mechanics. Indeed, nearly all quantum optics experiments rely on this separation, using individual point detectors that are scanned to measure coincidence counts and correlations. Scanning, however, is tedious, time consuming, and ill-suited for imaging. Moreover, the separation of beam paths adds complexity to the system while reducing the number of photons available for sampling, and the multiplicity of detectors does not scale well for greater numbers of photons and higher orders of entanglement. We bypass all of these problems here by directly imaging collinear photon pairs with an electron-multiplying CCD camera. We show explicitly the benefits of quantum nonlocality by engineering the spatial entanglement of the illuminating photons and introduce a new method of correlation measurement by converting time-domain coincidence counting into spatial-domain detection of selected pixels. We show that classical transport-of-intensity methods are applicable in the quantum domain and experimentally demonstrate nearly optimal (Heisenberg-limited) phase measurement for the given quantum illumination. The methods show the power of direct imaging and hold much potential for more general types of quantum information processing and control.

arXiv:1509.01227•Sep 3, 2015•1 citation

Imaging the Joint Probability Distribution of Spatially Entangled Photon Pairs with a Camera

Matthew C. Reichert, Hugo Defienne, Jason W. Fleischer

We present massively parallel coincidence counting of entangled photon pairs by measuring coincidences between all pairs of pixels in a single-photon-sensitive camera, including the case where both entangled photons arrive in the same pixel.

Imaging and Applied Optics•Jan 1, 2018•0 citations

Quantum-enhanced imaging and sensing with spatially correlated biphotons

Ermes Toninelli

In this thesis I discuss the experimental demonstration of quantum-enhanced imaging and sensing schemes able to surpass the performance of their classical counterparts. This is achieved by exploiting the spatial properties of quantum correlated biphotons. Over the next chapters I ﬁrst discuss the production and detection of quantum correlated photons using a type-I nonlinear crystal and a single-photon sensitive electron-multiplying CCD camera. I then provide a simple yet powerful description of the spatially resolved detection of biphotons, allowing to accurately model and assess the performance of the quantum-enhanced schemes featured in this thesis. These consist of a shadow-sensing and an imaging scheme able to respectively beat the shot-noise-limit in the optical measurement of the position of a shadow and the diﬀraction limit in the full-ﬁeld imaging of real-world objects. A combination of simulated and experimental results are used to investigate both the achieved and theoretically available quantum advantage. Optical losses and detector noise are found to limit the better-than-classical performance of the schemes, which rely on the ability to jointly detect an as high as possible number of spatially correlated biphotons.

•Jan 1, 2020•0 citations

Imaging High-dimensional Spaces with Spatially Entangled Photon Pairs

Matthew C. Reichert, Xiaohang Sun, Jason W. Fleischer

We directly measure the biphoton probability distribution within a 373 million dimensional Hilbert space using an electron multiplying CCD camera. These data allow for simultaneous characterization of correlations and their application for sub-diffraction-limited imaging.

Imaging and Applied Optics•Jan 1, 2016•1 citation

Abstract Losses should be accounted for in a complete description of quantum imaging systems, and yet they are often treated as undesirable and largely neglected. In conventional quantum imaging, images are built up by coincidence detection of spatially entangled photon pairs (biphotons) transmitted through an object. However, as real objects are non-unitary (absorptive), part of the transmitted state contains only a single photon, which is overlooked in traditional coincidence measurements. The single-photon part has a drastically different spatial distribution than the two-photon part. It contains information about both the object, and, remarkably, the spatial entanglement properties of the incident biphotons. Here, we image the one- and two-photon parts of the transmitted state using an electron multiplying CCD array, treating it both as a traditional camera and as a massively parallel coincidence counting apparatus, and demonstrate agreement with theoretical predictions of non-unitary quantum optics. This work may prove useful for photon-number imaging and may lead to techniques for entanglement characterization that do not require coincidence measurements.

We utilize a single-photon sensitive electron multiplying CCD camera as a massively parallel coincidence counting apparatus to study spatial entanglement of photon pairs. This allows rapid measurement of transverse spatial entanglement in a fraction of the time required with traditional point-scanning techniques. We apply this technique to quantum experiments on entangled photon pairs: characterization of the evolution of entanglement upon propagation, and measurement of one- and two-photon portions of the state transmitted through non-unitary (lossy) objects, and quantum phase imaging.

Entangled photons have the remarkable ability to be more sensitive to signal and less sensitive to noise than classical light. Joint photons can sample an object collectively, resulting in faster phase accumulation and higher spatial resolution, while common components of noise can be subtracted. Even more, they can accomplish this while physically separate, due to the nonlocal properties of quantum mechanics. Indeed, nearly all quantum optics experiments rely on this separation, using individual point detectors that are scanned to measure coincidence counts and correlations. Scanning, however, is tedious, time consuming, and ill-suited for imaging. Moreover, the separation of beam paths adds complexity to the system while reducing the number of photons available for sampling, and the multiplicity of detectors does not scale well for greater numbers of photons and higher orders of entanglement. We bypass all of these problems here by directly imaging collinear photon pairs with an electron-multiplying CCD camera. We show explicitly the benefits of quantum nonlocality by engineering the spatial entanglement of the illuminating photons and introduce a new method of correlation measurement by converting time-domain coincidence counting into spatial-domain detection of selected pixels. We show that classical transport-of-intensity methods are applicable in the quantum domain and experimentally demonstrate nearly optimal (Heisenberg-limited) phase measurement for the given quantum illumination. The methods show the power of direct imaging and hold much potential for more general types of quantum information processing and control.

In this thesis I discuss the experimental demonstration of quantum-enhanced imaging and sensing schemes able to surpass the performance of their classical counterparts. This is achieved by exploiting the spatial properties of quantum correlated biphotons. Over the next chapters I ﬁrst discuss the production and detection of quantum correlated photons using a type-I nonlinear crystal and a single-photon sensitive electron-multiplying CCD camera. I then provide a simple yet powerful description of the spatially resolved detection of biphotons, allowing to accurately model and assess the performance of the quantum-enhanced schemes featured in this thesis. These consist of a shadow-sensing and an imaging scheme able to respectively beat the shot-noise-limit in the optical measurement of the position of a shadow and the diﬀraction limit in the full-ﬁeld imaging of real-world objects. A combination of simulated and experimental results are used to investigate both the achieved and theoretically available quantum advantage. Optical losses and detector noise are found to limit the better-than-classical performance of the schemes, which rely on the ability to jointly detect an as high as possible number of spatially correlated biphotons.