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A theory of spontaneous parametric down-conversion, which gives rise to a quantum state that is entangled in multiple parameters, such as three-dimensional wavevector and polarization, allows us to understand the unusual characteristics of…

We address the problem of efficient modelling of photon pairs generated in spontaneous parametric down-conversion and coupled into single-mode fibers. It is shown that when the range of relevant transverse wave vectors is restricted by the…

Quantum Physics · Physics 2009-09-08 Piotr Kolenderski , Wojciech Wasilewski , Konrad Banaszek

Nonlinear spectroscopy with quantum entangled photons is an emerging field of research that holds the promise to achieve a superior signal-to-noise ratio and effectively isolate many-body interactions. Photon sources used for this purpose…

Spontaneous parametric downconversion (SPDC) has been a key enabling technology in exploring quantum phenomena and their applications for decades. For instance, traditional SPDC, which splits a high energy pump photon into two lower energy…

We investigate the procedure of Schmidt modes extraction in systems with continuous variables. An algorithm based on singular value matrix decomposition is applied to the study of entanglement in an "atom-photon" system with spontaneous…

Quantum Physics · Physics 2007-05-23 A. Yu. Bogdanov , Yu. I. Bogdanov , K. A. Valiev

Multiplexing information in different degrees of freedom and use of integrated and fiber-optic components are natural solutions to the scalability bottleneck in optical quantum communications and computing. However, for bulk-optics systems,…

Quantum Physics · Physics 2025-12-23 Natalia Costas , Nadia Belabas , David Barral

We show that in parametric down-conversion the coherence properties of a temporally partially coherent pump field get entirely transferred to the down-converted entangled two-photon field. Under the assumption that the frequency-bandwidth…

Quantum Physics · Physics 2017-07-24 Girish Kulkarni , Prashant Kumar , Anand K. Jha

Quantum entanglement, the non-separability of a multipartite wave function, became essential in understanding the non-locality of quantum mechanics. In optics, this non-locality can be demonstrated on impressively large length scales, as…

Quantum correlations are a vital resource in advanced information processing based on quantum phenomena. Remarkably, the vacuum state of a quantum field may act as a key element for the generation of multipartite quantum entanglement. In…

It is shown that parametric downconversion, with a short-duration pump pulse and a long nonlinear crystal that is appropriately phase matched, can produce a frequency-entangled biphoton state whose individual photons are coincident in…

Quantum Physics · Physics 2009-11-07 Vittorio Giovannetti , Lorenzo Maccone , Jeffrey H. Shapiro , Franco N. C. Wong

High-dimensional entangled states of light provide novel possibilities for quantum information, from fundamental tests of quantum mechanics to enhanced computation and communication protocols. In this context, the frequency degree of…

Quantum Physics · Physics 2020-04-10 S. Francesconi , F. Baboux , A. Raymond , N. Fabre , G. Boucher , A. Lemaître , P. Milman , M. I. Amanti , S. Ducci

We investigate the quantum state generated by optical parametric down-conversion in a $\chi^{(2) } $ medium driven by two noncollinear light modes. The analysis shows the emergence of multipartite, namely 3- or 4-partite, entangled states…

Quantum Physics · Physics 2021-05-05 Alessandra Gatti , Enrico Brambilla , Ottavia Jedrkiewicz

The on-chip integration of quantum light sources has enabled the realization of complex quantum photonic circuits. However, for the practical implementation of such circuits in quantum information applications it is crucial to develop…

We describe and demonstrate a quantum state tomography for measuring the complex temporal waveform of narrowband biphotons. Through six sets of two-photon interference measurements projected in different polarization subspaces, we can…

Quantum Physics · Physics 2015-01-14 Peng Chen , Chi Shu , Xianxin Guo , M. M. T. Loy , Shengwang Du

The first direct measurement of photon bunching (g2 correlation function) in one output arm of a spontaneous-parametric-down-conversion source operated with a continuous pump laser in the single-photon regime is demonstrated. The result is…

Spontaneous parametric downconversion is an essential technique in quantum optics experiments. In this paper, various quasi-phase-matching processes in several typical periodically polarized nonlinear materials are analyzed and calculated.…

Quantum Physics · Physics 2022-07-12 Xi-Yu Liu , Ya-Fei Yu , Zheng-Jun Wei , Tian-Ming Zhao , Jin-Dong Wang

We review some recent experiments based upon multimode two-photon interference of photon pairs created by spontaneous parametric down-conversion. The new element provided by these experiments is the inclusion of the transverse spatial…

Quantum Physics · Physics 2009-11-10 S. P. Walborn , W. A. T. Nogueira , A. N. de Oliveira , S. Pádua , C. H. Monken

We study the physics of four-photon states generated in spontaneous parametric down-conversion with a pulsed pump field. In the limit where the coherence time of the photons t_c is much shorter than the duration of the pump pulse Delta t,…

Spontaneous parametric down conversion has been shown to be a reliable source of entangled photons. Amongst the wide range of properties that have been shown to be entangled, it is the orbital angular momentum that is the focus of our…

Quantum Physics · Physics 2015-03-17 Filippo M. Miatto , Alison M. Yao , Stephen M. Barnett

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…