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Spatial modes of light directly give the most easily accessible degree of freedom that span an infinite dimensional Hilbert space. The higher dimensional spatial mode entanglement realized using spontaneous parametric down conversion (SPDC)…

Quantum Physics · Physics 2020-11-23 Ali Anwar , Nijil Lal , Shashi Prabhakar , R. P. Singh

A quantum system composed of two or more subsystems can be in an entangled state, i.e. a state in which the properties of the global system are well defined but the properties of each subsystem are not. Entanglement is at the heart of…

We present an integrated source of polarization entangled photon pairs in the telecom regime, which is based on type II-phasematched parametric down-conversion (PDC) in a Ti-indiffused waveguide in periodically poled lithium niobate. The…

Quantum Physics · Physics 2015-06-16 Harald Herrmann , Xu Yang , Abu Thomas , Andreas Poppe , Wolfgang Sohler , Christine Silberhorn

We report a novel and simple approach for generating near-perfect quality polarization entanglement in a fully guided-wave fashion. Both deterministic pair separation into two adjacent telecommunication channels and the paired photons'…

Quantum Physics · Physics 2012-09-12 F. Kaiser , A. Issautier , L. A. Ngah , O. Danila , H. Herrmann , W. Sohler , A. Martin , S. Tanzilli

Photonic quantum technologies utilize various degrees of freedom (DOFs) of light, such as polarization, frequency, and spatial modes, to encode quantum information. In the effort of further improving channel capacity of quantum…

Quantum Physics · Physics 2026-04-30 Roey Shafran , Ron Ziv , Mordechai Segev

Recently, two-photon six-qubit hyperentangled states were produced in experiment and they can improve the channel capacity of quantum communication largely. Here we present a scheme for the hyperentanglement purification of nonlocal…

Quantum Physics · Physics 2016-09-21 Guan-Yu Wang , Qian Liu , Fu-Guo Deng

Entangled photon pairs are crucial resources for quantum information processing protocols. Via the process of spontaneous parametric down-conversion (SPDC), we can generate these photon pairs using bulk nonlinear crystals. Traditionally,…

Quantum Physics · Physics 2024-04-12 Zi-Qi Zeng , Shi-Xin You , Zi-Xiang Yang , Chenzhi Yuan , Chenglong You , Rui-Bo Jin

We predict that all-optically reconfigurable generation of photon pairs with tailored spatial entanglement can be realized via spontaneous parametric down-conversion in integrated nonlinear coupled waveguides. The required elements of the…

We report the entanglement of topological features, namely, isolated, linked optical vortex loops in the light from spontaneous parametric down-conversion (SPDC). In three dimensions, optical vortices are lines of phase singularity and…

Quantum Physics · Physics 2011-01-20 J. Romero , J. Leach , B. Jack , M. R. Dennis , S. Franke-Arnold , S. M. Barnett , M. J. Padgett

We theoretically investigate polarization-entangled photon generation by using a semiconductor quantum dot embedded in a microcavity. The entangled states can be produced by the application of two cross-circularly polarized laser fields.…

A novel ultrabright parametric source of polarization entangled photon pairs with striking spatial characteristics is reported. The distribution of the output electromagnetic k-modes excited by Spontaneous Parametris Down Conversion and…

Quantum Physics · Physics 2007-05-23 G. Di Nepi , F. De Martini , M. Barbieri , P. Mataloni

We report the demonstration of a bulk, intrinsically phase-stable source of polarization- and time-energy-entangled photon pairs at 810nm and 1550nm, directly coupled into single-mode optical fibers. This highly non-degenerate wavelength…

We present a source of polarization entangled photon pairs based on spontaneous parametric downconversion engineered for frequency uncorrelated telecom photon generation. Our source provides photon pairs that display, simultaneously, the…

Double-pair emission from type-II parametric down conversion results in a highly entangled 4-photon state. Due to interference, which is similar to bunching from thermal emission, this state is not simply a product of two pairs. The…

Quantum Physics · Physics 2009-11-07 Harald Weinfurter , Marek Zukowski

We measure the transverse entanglement of photon pairs on their propagation from the near to the far field of spontaneous parametric downconversion (SPDC). The Fedorov ratio, depending on the widths of conditional and unconditional…

Quantum Physics · Physics 2015-06-12 Felix Just , Andrea Cavanna , Maria V. Chekhova , Gerd Leuchs

Using polarization entangled photon pairs, we demonstrate a robust scheme for quantum illumination and ranging in a lossy environment. Entangled photon pairs are generated in a Sagnac interferometer configuration, yielding high-visibility…

The ability to generate quantum entangled photon pairs through spontaneous parametric down conversion (SPDC) is playing a pivotal role in many applications in quantum technologies, including quantum communications, quantum computation, and…

Optics · Physics 2025-06-24 Tongmiao Fan , Jihua Zhang , Andrey A. Sukhorukov

Recently the engineering of the entanglement for photon pairs generated during the spontaneous parametric down conversion process (SPDC) can be achieved via manipulation of pump wavelength behind a \c{hi}(2)-based type II SPDC process [1].…

Quantum Physics · Physics 2017-02-23 Amin Babazadeh , Rahman Nouroozi

The state of the spatially correlated down-converted photons is usually treated as a two-mode Gaussian entangled state. While intuitively this seems to be reasonable, it is known that new structures in the spatial distributions of these…

Quantum Physics · Physics 2015-03-19 E. S. Gómez , W. A. T. Nogueira , C. H. Monken , G. Lima

The dependence of one- and two-photon characteristics of pulsed entangled two-photon fields generated in spontaneous parametric down-conversion on the pump-pulse properties (shape of the pump-pulse spectrum and its internal structure) is…

Quantum Physics · Physics 2009-10-31 Jan Perina