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We develop an original approach for the quantitative characterisation of the entanglement properties of, possibly mixed, bi- and multipartite quantum states of arbitrary finite dimension. Particular emphasis is given to the derivation of…

Quantum Physics · Physics 2009-11-11 Florian Mintert , Andre R. R. Carvalho , Marek Kus , Andreas Buchleitner

Entanglement is recognized as a key resource for quantum computation and quantum cryptography. For quantum metrology, the use of entangled states has been discussed and demonstrated as a means of improving the signal-to-noise ratio. In…

Quantum Physics · Physics 2007-05-23 C. F. Roos , M. Chwalla , K. Kim , M. Riebe , R. Blatt

We consider the problem of determining the state of a quantum system given one or more readings of the expectation value of an observable. The system is assumed to be a finite dimensional quantum control system for which we can influence…

Quantum Physics · Physics 2009-11-10 Domenico D'Alessandro

We show that probabilities of results of all possible measurements performing on a quantum system depend on the system's state only through its density matrix. Therefore all experimentally available information about the state contains in…

Quantum Physics · Physics 2016-02-01 Alexey Nenashev

We study quantum steering experiments without assuming that the trusted party can perfectly control their measurement device. Instead, we introduce a scenario in which these measurements are subject to small imprecision. We show that small…

Quantum Physics · Physics 2024-02-19 Armin Tavakoli

A promising practical application of entanglement is metrology, where quantum states can be used to make measurements beyond the shot noise limit. Here we consider how metrology schemes could be realised using atomic Bose-Einstein…

Quantum Physics · Physics 2015-05-27 J. A. Dunningham , J. J. Cooper , D. W. Hallwood

We introduce a new class of quantum many-particle entangled states, called the Dicke squeezed (or DS) states, which can be used to improve the precision in quantum metrology beyond the standard quantum limit. We show that the enhancement in…

Quantum Physics · Physics 2015-06-22 Zhen Zhang , Luming Duan

This review summarizes and amplifies on recent investigations of coupled quantum dynamical systems in the short wavelength limit. We formulate and attempt to answer three fundamental questions: (i) What drives a dynamical quantum system to…

Quantum Physics · Physics 2009-04-25 Ph. Jacquod , C. Petitjean

It is demonstrated that two distant quantum wells separated by a reservoir with a continuous spectrum can possess bound eigenstates embedded in the continuum. These represent a linear superposition of quantum states localized in the wells.…

Quantum Physics · Physics 2015-05-27 Jing Ping , Xin-Qi Li , Shmuel Gurvitz

We show that the correlations in stochastic outputs of time-distributed weak measurements can be used to study the dynamics of an individual quantum object, with a proof-of-principle setup based on small Faraday rotation caused by a single…

Mesoscale and Nanoscale Physics · Physics 2010-01-20 R. -B. Liu , Shu-Hong Fung , Hok-Kin Fung , A. N. Korotkov , L. J. Sham

Unlike closed systems, where the total energy and information are conserved within the system, open systems interact with the external environment which often leads to complex behaviors not seen in closed systems. The random fluctuations…

Quantum Physics · Physics 2024-05-24 Joo Yong Shim , Joongheon Kim

Symmetric quantum states are fascinating objects. They correspond to multipartite systems that remain invariant under particle permutations. This symmetry is reflected in their compact mathematical characterisation but also in their unique…

Quantum Physics · Physics 2025-07-15 Carlo Marconi , Guillem Müller-Rigat , Jordi Romero-Pallejà , Jordi Tura , Anna Sanpera

The stochastic Schr\"odinger equation, of classical or quantum type, allows to describe open quantum systems under measurement in continuous time. In this paper we review the link between these two descriptions and we study the properties…

Quantum Physics · Physics 2013-09-03 Alberto Barchielli , Matteo Gregoratti

This study deals with continuous limits of interacting one-dimensional diffusive systems, arising from stochastic distortions of discrete curves with various kinds of coding representations. These systems are essentially of a…

Statistical Mechanics · Physics 2011-09-09 Guy Fayolle , Cyril Furtlehner

Continuous quantum measurement is the backbone of various methods in quantum control, quantum metrology, and quantum information. Here, we present a generalized formulation of dispersive measurement of a complex quantum systems. We describe…

Quantum Physics · Physics 2014-04-29 A. Shabani , J. Roden , K. B. Whaley

A controlled quantum dense coding scheme is investigated with a four-particle non-maximal quantum channel. The amount of classical information is shown to be capable of being controlled by the controllers through adjustments of the local…

Quantum Physics · Physics 2007-05-23 Chang-Bao Fu , Yan Xia , Bo-Xue Liu , Shou Zhang , Kyu-Hwang Yeon , Chung-In Um

We study the dynamics of the two-level atomic systems (qubits) under a double-layer environment that is consisted of a network of single-mode cavities coupled to a common reservoir. A general exact master equation for the dynamics can be…

Quantum Physics · Physics 2019-05-21 Yu-Long Qiao , Jia-Ming Zhang , Yusui Chen , Jun Jing , Shi-Yao Zhu

Long-range entangled states are vital for quantum information processing and quantum metrology. Preparing such states by combining measurements with unitary gates opened new possibilities for efficient protocols with finite-depth quantum…

Quantum Physics · Physics 2024-08-07 Iosifina Angelidi , Marcin Szyniszewski , Arijeet Pal

We present a simple derivation of the density of states (DOS) in confined nanomaterials. While previous studies often apply a heuristic $L^{3-d}$ confinement factor to bulk DOS expressions, we show that this factor arises naturally from a…

Quantum Gases · Physics 2026-02-03 Benedick Andrade , Rayda Gammag

We investigate the process of quantum measurements on scattered probes. Before scattering, the probes are independent, but they become entangled afterwards, due to the interaction with the scatterer. The collection of measurement results…

Mathematical Physics · Physics 2015-03-23 Marco Merkli , Mark Penney