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We demonstrate that the entanglement in a class of two-mode non-Gaussian states obtained by subtracting photons from Gaussian twin beams can be bounded from above and from below by functionals of the second moments only. Knowledge of the…

Quantum Physics · Physics 2009-02-15 Gerardo Adesso

We consider the problem of evaluating the entanglement of non-Gaussian mixed states generated by photon subtraction from entangled squeezed states. The entanglement measures we use are the negativity and the logarithmic negativity. These…

Quantum Physics · Physics 2007-05-23 Akira Kitagawa , Masahiro Takeoka , Masahide Sasaki , Anthony Chefles

In the field of continuous-variable quantum information processing, non-Gaussian states with negative values of the Wigner function are crucial for the development of a fault-tolerant universal quantum computer. While several non-Gaussian…

We study the production of entangled two- and N-mode quantum states of light in optical waveguides. To this end, we propose a quantum photonic circuit that produces a reconfigurable superposition of photon subtraction on two single-mode…

Quantum Physics · Physics 2020-05-05 David Barral , Jesús Liñares , Daniel Balado

Strongly correlated multi-photon states are indispensable resources for advanced quantum technologies, yet their deterministic generation remains challenging due to the inherent weak nonlinearity in most optical systems. Here, we propose a…

Quantum Physics · Physics 2025-11-19 Jia-Qi Li , Anton Frisk Kockum , Xin Wang

We provide a family of Non-Gaussian pure entangled states in a bipartite system as the eigen states of a quadratic Hamiltonian composed of the Einstein-Podolsky-and-Rosen-like operators. The ground state of the Hamiltonian corresponds to…

Quantum Physics · Physics 2010-01-12 Ryo Namiki

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…

Quantum technologies are powered by platforms to generate complex non-classical states of matter or light to realize applications. We investigate the non-classical properties of high-harmonic generation in semiconductors, an emerging…

Quantum Physics · Physics 2026-03-18 David Theidel , Mackrine Nahra , Ilya Karuseichyk , Houssna Griguer , Mateusz Weis , Hamed Merdji

We provide a general decomposition of the two-photon state produced by spontaneous parametric down-conversion in Hermite-Gaussian modes, in the case that the pump beam is described by a Hermite-Gaussian beam of any order. We show that the…

Quantum Physics · Physics 2012-08-22 S. P. Walborn , A. H. Pimentel

Multimode multiphoton states are at the center of many photonic quantum technologies, from photonic quantum computing to quantum sensing. In this work, we derive a procedure to generate exactly, and with a predictable number of steps, any…

We investigate the process of entangled state of light generation while propagation along a one dimensional array of single-mode nonlinear waveguides. We consider a situation when entanglement is formed due to spontaneous parametric…

Quantum Physics · Physics 2019-07-08 V. O. Martynov , V. A. Mironov , L. A. Smirnov

Maximally entangled photon pairs with a spatial degree of freedom is a potential way for realizing high-capacity quantum computing and communication. However, methods to generate such entangled states with high quality, high brightness, and…

We introduce a new quantity for describing nonclassicality of an arbitrary optical two-mode Gaussian state which remains invariant under any global photon-number preserving unitary transformation of the covariance matrix of the state. The…

Quantum Physics · Physics 2016-07-08 Ievgen I. Arkhipov , Jan Peřina , Jiří Svozilík , Adam Miranowicz

Multiple photon subtraction applied to a displaced phase-averaged coherent state, which is a non-Gaussian classical state, produces conditional states with a non trivial (positive) Glauber-Sudarshan $P$-representation. We theoretically and…

Quantum Physics · Physics 2013-12-02 Stefano Olivares , Alessia Allevi , Maria Bondani

We describe a protocol capable of preparing an arbitrary state of two photons in several spatial modes using pairs of photons generated by spontaneous parametric down-conversion, linear optical elements and single-photon detectors or…

Quantum Physics · Physics 2009-11-13 Karel Lemr , Jaromir Fiurasek

We report on the experimental generation of an entangled state with a spectrally pure heralded single-photon state and a weak coherent state. By choosing group-velocity matching in the nonlinear crystal, our system for producing entangled…

We introduce nonlinear canonical transformations that yield effective Hamiltonians of multiphoton down conversion processes, and we define the associated non-Gaussian multiphoton squeezed states as the coherent states of the multiphoton…

Quantum Physics · Physics 2007-05-23 Silvio De Siena , Antonio Di Lisi , Fabrizio Illuminati

We introduce a protocol for generating a broad class of non-Gaussian (nG) quantum states via postselected weak measurement techniques. The scheme involves injecting an arbitrary quantum state and a single photon into the signal and idler…

Quantum Physics · Physics 2025-12-29 Xiao-Xi Yao , Yusuf Turek

We study the measurement-induced non-Gaussian operation on the single- and two-mode \textit{Gaussian} squeezed vacuum states with beam splitters and on-off type photon detectors, with which \textit{mixed non-Gaussian} states are generally…

Quantum Physics · Physics 2009-11-11 Akira Kitagawa , Masahiro Takeoka , Kentaro Wakui , Masahide Sasaki

We investigate how entangled coherent states and superpositions of low intensity coherent states of non-Gaussian nature can be generated via non-resonant interaction between either two linearly or circularly polarized field modes and an…

Quantum Physics · Physics 2009-11-13 R. J. Missori , M. C. de Oliveira , K. Furuya