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Uncertainty relations are fundamental to quantum mechanics, encoding limits on the simultaneous measurement of conjugate observables. Violations of joint uncertainty bounds can certify entanglement -- a resource critical for quantum…

Quantum Physics · Physics 2025-12-11 Felipe Reibnitz Willemann , Mauro Antezza , Johannes Feist

Particle entanglement is a fundamental resource upon which are based many quantum technologies. However, the up-to-now best sources of entangled photons rely on parametric down-conversion processes, which are optimal only at certain…

It is shown that spatial correlation functions measured for correlated photon pairs at the single-photon level correspond to speckle patterns visible at high intensities. This correspondence is observed for the first time in one…

Quantum Physics · Physics 2015-06-19 Radek Machulka , Ondrej Haderka , Jan Perina , Marco Lamperti , Alessia Allevi , Maria Bondani

We use a fiber based double slit Young interferometer for studying the far-field spatial distribution of the two-photon coincidence rate (coincidence pattern) for various quantum states with different degree of spatial entanglement. The…

Quantum Physics · Physics 2015-06-18 Ivan B. Bobrov , Dmitry A. Kalashnikov , Leonid A. Krivitsky

For a wide range of applications a fast, non-destructive, remote, and sensitive identification of samples with predefined characteristics is preferred instead of their full characterization. Here, we report on the experimental…

We consider the measuring procedure that in principle allows to avoid the homodyne detection for the simultaneous selection of both quadrature components in the far-field. The scheme is based on the use of the coherent sources of the…

Quantum Physics · Physics 2015-05-13 T. Golubeva , Yu. Golubev , K. Samburskaya , C. Fabre , N. Treps , M. Kolobov

We describe a criterion for the detection of entanglement between two multi-boson systems. The criterion is based on calculating correlations of Gell-Mann matrices with a fixed boson number on each subsystem. This applies naturally to…

We propose a scheme to explore two-photon high-dimensional entanglement associated with a transverse pattern by means of two-photon interference in a beamsplitter. We find that the topological symmetry of the angular spectrum of the…

Quantum Physics · Physics 2009-11-11 Gui-Fang Dang , Li-Ping Deng , Kaige Wang

We use a single trapped 40Ca+ ion as a resonant, polarization-sensitive absorber to detect and characterize the entanglement of tunable narrowband photon pairs from a spontaneous parametric down-conversion source. Single-photon absorption…

Quantum Physics · Physics 2013-04-22 J. Huwer , J. Ghosh , N. Piro , M. Schug , F. Dubin , J. Eschner

Recent theoretical studies in quantum spectroscopy have emphasized the potential of non-classical correlations in entangled photon pairs for selectively targeting specific nonlinear optical processes in nonlinear optical responses. However,…

Chemical Physics · Physics 2026-04-21 Yuta Fujihashi , Ozora Iso , Ryosuke Shimizu , Akihito Ishizaki

Spectrally correlated photon pairs can be used to improve performance of long range fiber based quantum communication protocols. We present a source based on spontaneous parametric down-conversion producing polarization entangled photons…

Optics · Physics 2014-03-28 Thomas Lutz , Piotr Kolenderski , Thomas Jennewein

Entanglement is the basic building block of quantum technologies whose property is in the unique quantum feature of nonlocal realism. However, such a nonlocal quantum property is known as just a weird phenomenon that cannot be obtained by…

Quantum Physics · Physics 2023-04-28 B. S. Ham

High-dimensional entangled states offer higher information capacity and stronger resilience to noise compared with two-dimensional systems. However, the large number of modes and sensitivity to random rotations complicate experimental…

Quantum Physics · Physics 2025-12-02 Ohad Lib , Shuheng Liu , Ronen Shekel , Qiongyi He , Marcus Huber , Yaron Bromberg , Giuseppe Vitagliano

Quantum transduction between microwave and optics can be realized by quantum teleportation if given reliable microwave-optical entanglement, namely entanglement-based quantum transduction. To realize this protocol, an entangled source with…

Quantum Physics · Physics 2020-04-01 Changchun Zhong , Xu Han , Hong X. Tang , Liang Jiang

Quantum information is often carried in the frequency and polarization degrees of freedom (DoFs) in single photons and entangled photons. We demonstrate a new approach to couple and decouple the frequency and polarization DoFs of broadband…

Quantum Physics · Physics 2023-11-27 Arash Riazi , Eric Y. Zhu , Dan Xu , Li Qian

Quantum imaging enhances imaging systems performance, potentially surpassing fundamental limits such as noise and resolution. However, these schemes have limitations and are still a long way from replacing classical techniques. Therefore,…

Quantum Physics · Physics 2024-02-13 Patrick Cameron , Baptiste Courme , Daniele Faccio , Hugo Defienne

A pair of optical pulses traveling through two dispersive media will become broadened and, as a result, the degree of coincidence between the optical pulses will be reduced. For a pair of entangled photons, however, nonlocal dispersion…

Quantum Physics · Physics 2015-05-13 So-Young Baek , Young-Wook Cho , Yoon-Ho Kim

We present an entanglement-based quantitative phase gradient microscopy technique that employs principles from quantum ghost imaging and ghost diffraction. In this method, a transparent sample is illuminated by both photons of an entangled…

Quantum Physics · Physics 2026-03-09 Yingwen Zhang , Paul-Antoine Moreau , Duncan England , Ebrahim Karimi , Benjamin Sussman

We discuss the conclusions that can be drawn on a recent experimental micro-macro entanglement test [F. De Martini, F. Sciarrino, and C. Vitelli, Phys. Rev. Lett. 100, 253601 (2008). The system under investigation is generated through…

Quantum Physics · Physics 2010-12-22 Nicolo' Spagnolo , Chiara Vitelli , Fabio Sciarrino , Francesco De Martini

We experimentally demonstrate a general criterion to identify entangled states useful for the estimation of an unknown phase shift with a sensitivity higher than the shot-noise limit. We show how to exploit this entanglement on the examples…