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We study the effective theory of soft photons in slowly varying electromagnetic background fields at one-loop order in QED. This is of relevance for the study of all-optical signatures of quantum vacuum nonlinearity in realistic…

High Energy Physics - Phenomenology · Physics 2017-03-14 Felix Karbstein

We report on the quantification of entanglement by means of entanglement measures on a four- and a six- qubit cluster state realized by using photons entangled both in polarization and linear momentum. This paper also addresss the question…

Quantum Physics · Physics 2011-03-23 H. Wunderlich , G. Vallone , P. Mataloni , M. B. Plenio

Quantum state tomography aims to determine the state of a quantum system as represented by a density matrix. It is a fundamental task in modern scientific studies involving quantum systems. In this paper, we study estimation of…

Statistics Theory · Mathematics 2016-03-25 Tony Cai , Donggyu Kim , Yazhen Wang , Ming Yuan , Harrison H. Zhou

The exact diagonalization technique is used to study many-particle properties of interacting electrons with spin, confined in a two-dimensional harmonic potential. The single-particle basis is limited to the lowest Landau level. The results…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 M. Koskinen , S. M. Reimann , J. -P. Nikkarila , M. Manninen

Practical quantum state tomography is usually performed by carrying out repeated measurements on many copies of a given state. The accuracy of the reconstruction depends strongly on the dimensionality of the system and the number of copies…

Quantum Physics · Physics 2008-07-08 Alex Ling , Antia Lamas-Linares , Christian Kurtsiefer

One way to explore multiparticle entanglement is to ask for maximal entanglement with respect to different bipartitions, leading to the notion of absolutely maximally entangled states or perfect tensors. A different path uses unitary…

Quantum Physics · Physics 2024-01-26 Fabian Bernards , Otfried Gühne

Theoretical analysis is presented on quantum state evolution of polarization light waves at frequencies $\omega_{o}$ and $\omega_{e}$ in a periodically poled nonlinear crystal (PPNC). It is shown that the variances of all the four Stokes…

Optics · Physics 2007-05-23 V. G. Dmitriev , R. Singh

We put the pure-state decomposition mathematical property of a mixed state to a physical test. We begin by characterizing all the possible decompositions of a rank-two mixed state by means of the complex overlap between two involved states.…

Quantum Physics · Physics 2015-05-20 Luis Roa , Alejandra Maldonad-Trapp , Marcelo Alid

Quantum theory stipulates that if two particles are identical in all physical aspects, the allowed states of the system are either symmetric or antisymmetric with respect to permutations of the particle labels. Experimentally, the symmetry…

Quantum theoretical treatment of coherent forward scattering of light in a polarized atomic ensemble with an arbitrary angular momentum is developed. We consider coherent forward scattering of a weak radiation field interacting with a…

Quantum Physics · Physics 2007-05-23 D. V. Kupriyanov , O. S. Mishina , I. M. Sokolov , B. Julsgaard , E. S. Polzik

Majorana bound states in topological superconductors have attracted intense research activity in view of applications in topological quantum computation. However, they are not the only example of topological bound states that can occur in…

Mesoscale and Nanoscale Physics · Physics 2022-03-18 Lucia Vigliotti , Fabio Cavaliere , Matteo Carrega , Niccolò Traverso Ziani

We study both manipulation and detection of two-mode spatial quantum states of light by means of a reconfigurable integrated device built in an electro-optical material in a Kolgelnik-Schmidt configuration, which provides higher error…

Quantum Physics · Physics 2020-04-13 David Barral , Mark G. Thompson , Jesús Liñares

Electromagnetic multipoles have been broadly adopted as a fundamental language throughout photonics, of which general features such as radiation patterns and polarization distributions are generically known, while their singularities and…

Optics · Physics 2019-04-22 Weijin Chen , Yuntian Chen , Wei Liu

Quantum states that are symmetric with respect to permutations of their subsystems appear in a wide range of physical settings, and they have a variety of promising applications in quantum information science. In this thesis the…

Quantum Physics · Physics 2013-02-08 Martin Aulbach

We analyze the properties of entangled random pure states of a quantum system partitioned into two smaller subsystems of dimensions $N$ and $M$. Framing the problem in terms of random matrices with a fixed-trace constraint, we establish,…

Statistical Mechanics · Physics 2016-05-11 Pierpaolo Vivo , Mauricio P. Pato , Gleb Oshanin

We show that for any energy observable every extreme point of the set of quantum states with bounded energy is a pure state. This allows us to write every state with bounded energy in terms of a continuous convex combination of pure states…

Quantum Physics · Physics 2021-09-28 Stephan Weis , Maksim Shirokov

We report on the experimental implementation of a polarimeter based on a scheme known to be optimal for obtaining the polarization vector of ensembles of spin-1/2 quantum systems, and the alignment procedure for this polarimeter is…

Quantum Physics · Physics 2007-05-23 Alexander Ling , Soh Kee Pang , Antia Lamas-Linares , Christian Kurtsiefer

Density matrices of pure multiphoton Fock polarization states and of arising from them reduced density matrices of mixed states are expressed in similar ways in terms of matrices of correlators defined as averaged products of equal numbers…

Quantum Physics · Physics 2019-05-08 S. V. Vintskevich , D. A. Grigoriev , N. I. Miklin , M. V. Fedorov

Subsystems of composite quantum systems are described by reduced density matrices, or quantum marginals. Important physical properties often do not depend on the whole wave function but rather only on the marginals. Not every collection of…

Quantum Physics · Physics 2014-10-31 Michael Walter

Theoretical analysis is presented on quantum state evolution of polarization light waves at frequencies $\omega_{o}$ and $\omega_{e}$ in a periodically poled nonlinear crystal (PPNC). It is shown that the variances of all the four Stokes…

Quantum Physics · Physics 2009-04-24 V. G. Dmitriev , R. Singh