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Tomography of a quantum state is usually based on positive operator-valued measure (POVM) and on their experimental statistics. Among the available reconstructions, the maximum-likelihood (MaxLike) technique is an efficient one. We propose…

Entanglement, a key feature of quantum mechanics, is a resource that allows the improvement of precision measurements beyond the conventional bound reachable by classical means. This is known as the standard quantum limit, already defining…

Other Condensed Matter · Physics 2008-12-09 J. Esteve , C. Gross , A. Weller , S. Giovanazzi , M. K. Oberthaler

A model of quantum measurement is proposed, which aims to describe statistical mechanical aspects of this phenomenon, starting from a purely Hamiltonian formulation. The macroscopic measurement apparatus is modeled as an ideal Bose gas, the…

Statistical Mechanics · Physics 2016-08-31 Armen E. Allahverdyan , Roger Balian , Theo M. Nieuwenhuizen

Collective measurements can project a system into an entangled state with enhanced sensitivity for measuring a quantum phase, but measurement back-action has limited previous efforts to only modest improvements. Here we use a collective…

We propose a quantum interface which applies multiple passes of a pulse of light through an atomic sample with phase/polarization rotations in between the passes. Our proposal does not require nonclassical light input or measurements on the…

Quantum Physics · Physics 2010-04-28 K. Hammerer , K. Molmer , E. S. Polzik , J. I. Cirac

An open quantum system, whose time evolution is governed by a master equation, can be driven into a given pure quantum state by an appropriate design of the system-reservoir coupling. This points out a route towards preparing many body…

Quantum Physics · Physics 2009-05-18 S. Diehl , A. Micheli , A. Kantian , B. Kraus , H. P. Büchler , P. Zoller

Quantum retrodiction involves finding the probabilities for various preparation events given a measurement event. This theory has been studied for some time but mainly as an interesting concept associated with time asymmetry in quantum…

Quantum Physics · Physics 2009-11-07 David T. Pegg , Stephen M. Barnett , John Jeffers

We propose a protocol to achieve high fidelity quantum state teleportation of a macroscopic atomic ensemble using a pair of quantum-correlated atomic ensembles. We show how to prepare this pair of ensembles using quasiperfect quantum state…

Quantum Physics · Physics 2009-11-10 Aurelien Dantan , Nicolas Treps , Alberto Bramati , Michel Pinard

Quantum Process Tomography (QPT) methods aim at identifying, i.e. estimating, a given quantum process. QPT is a major quantum information processing tool, since it especially allows one to characterize the actual behavior of quantum gates,…

Quantum Physics · Physics 2020-05-06 Yannick Deville , Alain Deville

Quantum many-body systems provide a unique platform for exploring the rich interplay between chaos, randomness, and complexity. In a recently proposed paradigm known as deep thermalization, random quantum states of system A are generated by…

Quantum Physics · Physics 2025-06-17 Wai-Keong Mok , Tobias Haug , Adam L. Shaw , Manuel Endres , John Preskill

In a two level atom, real-time quantum state holography is performed through interferences between quantum states created by a reference pulse and a chirped pulse resulting in coherent transients. A sequence of several measurements allows…

Atomic Physics · Physics 2016-08-16 Antoine Monmayrant , Béatrice Chatel , Bertrand Girard

A way is presented to design quantum wave functions that exhibit backflow, namely negative probability current despite having a strictly positive spectrum of momentum. These wave functions are derived from rational complex functions which…

Quantum Physics · Physics 2023-08-21 Ioannis Chremmos

In a recent, modified double-pinhole diffraction experiment the existence of an interference pattern was established indirectly along with a near-perfect imaging of the double pinhole. Our theoretical analysis shows that the experiment…

Quantum Physics · Physics 2013-06-27 J. C. G. Biniok , P. Busch

This paper introduces the first quantum computing framework for Stochastic Quantum Power Flow (SQPF) analysis in power systems. The proposed method leverages quantum states to encode power flow distributions, enabling the use of Quantum…

Quantum Physics · Physics 2025-01-13 Brynjar Sævarsson , Hjörtur Jóhannsson , Spyros Chatzivasileiadis

The quantum state of a light beam can be represented as an infinite dimensional density matrix or equivalently as a density on the plane called the Wigner function. We describe quantum tomography as an inverse statistical problem in which…

Statistics Theory · Mathematics 2007-06-13 L. M. Artiles , R. D. Gill , M. I. Guta

Backflow is a counter-intuitive phenomenon in which a forward propagating quantum particle propagates locally backwards. The actual counter-propagation property associated with this delicate interference phenomenon has not been observed to…

Optics · Physics 2018-11-26 Yaniv Eliezer , Thomas Zacharias , Alon Bahabad

In this paper we explore the rich structure of macroscopic many-particle quantum states for Bose- Einstein condensate in an optical cavity with the tunable nonlinear atom-photon interaction [Nature (London) 464, 1301 (2010)]. Population…

Quantum Gases · Physics 2015-06-19 Xiuqin Zhao , Ni Liu , J-Q Liang

Ensembles with long-range interactions between particles are promising for revealing strong quantum collective effects and many-body phenomena. Here we study the ground-state phase diagram of a two-dimensional Bose system with quadrupolar…

Quantum Gases · Physics 2021-04-07 G. E. Astrakharchik , I. L. Kurbakov , D. V. Sychev , A. K. Fedorov , Yu. E. Lozovik

Precision interferometry with atomic wavepackets confined in a one-dimensional optical lattice is an emergent paradigm in quantum sensing of forces and fields, with applications in gravimetry, accelerometry, geophysics, and fundamental…

Quantum Gases · Physics 2026-05-28 Emmett Hough , Tahiyat Rahman , Forest Tschirhart , Subhadeep Gupta

Quantum state tomography (QST) is the process of reconstructing the complete state of a quantum system (mathematically described as a density matrix) through a series of different measurements. These measurements are performed on a number…

Quantum Physics · Physics 2025-01-08 Hailan Ma , Zhenhong Sun , Daoyi Dong , Dong Gong