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It has recently been argued that the inability to measure the absolute phase of an electromagnetic field prohibits the representation of a laser's output as a quantum optical coherent state. This argument has generally been considered…

Quantum Physics · Physics 2009-11-10 Kae Nemoto , Samuel L. Braunstein

Quantum entanglement of pure states of a bipartite system is defined as the amount of local or marginal ({\em i.e.}referring to the subsystems) entropy. For mixed states this identification vanishes, since the global loss of information…

Quantum Physics · Physics 2007-05-23 Gerardo Adesso , Alessio Serafini , Fabrizio Illuminati

Entanglement of remote atom lasers is obtained via quantum state transfer technique from lights to matter waves in a five-level $M$-type system. The considered atom-atom collisions can yield an effective Kerr susceptibility for this system…

Quantum Physics · Physics 2007-05-23 Xiong-Jun Liu , Hui Jing , Xin Liu , Ming-Sheng Zhan , Mo-Lin Ge

We develop a quantum learning scheme for binary discrimination of coherent states of light. This is a problem of technological relevance for the reading of information stored in a digital memory. In our setting, a coherent light source is…

Quantum Physics · Physics 2015-07-09 Gael Sentís , Madalin Guta , Gerardo Adesso

We study the dynamical process of disentanglement of two qubits and two qutrits coupled to an Ising spin chain in a transverse field, which exhibits a quantum phase transition. We use the concurrence and negativity to quantify entanglement…

Quantum Physics · Physics 2009-11-13 Zhe Sun , Xiaoguang Wang , C. P. Sun

Decoherence is the process via which quantum superpositions states are reduced to classical mixtures. Decoherence has been predicted for relativistically accelerated quantum systems, however examples to date have involved restricting the…

Quantum Physics · Physics 2019-01-16 Daiqin Su , Timothy C. Ralph

Entangled many-body states are an essential resource for quantum computing and interferometry. Determining the type of entanglement present in a system usually requires access to an exponential number of parameters. We show that in the case…

Quantum Physics · Physics 2014-11-17 Michael Walter , Brent Doran , David Gross , Matthias Christandl

We derive a model for a single mode laser that includes all two particle quantum correlations between photons and electrons. In contrast to the predictions of semi-classical models, we find that lasing takes place in the presence of quantum…

We consider the most general (finite-dimensional) quantum mechanical information source, which is given by a quantum system $A$ that is correlated with a reference system $R$. The task is to compress $A$ in such a way as to reproduce the…

Quantum Physics · Physics 2024-09-26 Zahra Baghali Khanian , Andreas Winter

Using Lindblad approach to study decoherence of quantum systems, we study the decoherence and decay of entangled states, formed by two basic states of a chain of thee qubits. We look on these states for a possible regular dependence on…

Quantum Physics · Physics 2015-03-13 Gustavo V. Lopez , Gustavo Montes

Entanglement is the resource to overcome the natural limitations of spatially separated parties restricted to Local Operations assisted by Classical Communications (LOCC). Recently two new classes of operational entanglement measures, the…

Quantum Physics · Physics 2016-01-06 D. Sauerwein , K. Schwaiger , M. Cuquet , J. I. de Vicente , B. Kraus

The control and manipulation of quantum-entangled non-local states is a crucial step for the development of quantum information processing. A promising route to achieve such states on a wide scale is to couple solid-state quantum emitters…

Optics · Physics 2022-07-06 J. -B Trebbia , Q Deplano , P Tamarat , B Lounis

Sensors for mapping the trajectory of an incoming particle find important utility in experimental high energy physics and searches for dark matter. For a quantum sensing protocol that uses projective measurements on a multi-qubit sensor…

Quantum Physics · Physics 2024-10-10 Zachary E. Chin , David R. Leibrandt , Isaac L. Chuang

This Letter verifies the potential of several classes of entangled coherent state in well known quantum metrology which includes detection of classical external force, and shows that there is a class of entangled coherent state for the…

Quantum Physics · Physics 2012-01-10 Osamu Hirota , Kentaro Kato , Dan Murakami

A theory of Steady-State laser action is presented which loosely parallels the treatment by H. Frohlich on energy storage in biological systems. The principal lasing elements, taken as N bio level molecules and a single mode quantized…

Quantum Physics · Physics 2012-09-18 Frederick W. Cummings , Michael T. Tavis

Entanglement and coherence are fundamental properties of quantum systems, promising to power near future quantum technologies, such as quantum computation, quantum communication and quantum metrology. Yet, their quantification, rather than…

We propose a scheme for generating steady entanglement between two distant atomic qubits in the coupled-cavity system via laser cooling. With suitable choice of the laser frequencies, the target entangled state is the only ground state that…

Quantum Physics · Physics 2013-01-04 Li Tuo Shen , Xin Yu Chen , Zhen Biao Yang , Huai Zhi Wu , Shi Biao Zheng

The degree to which a pure quantum state is entangled can be characterized by the distance or angle to the nearest unentangled state. This geometric measure of entanglement is explored for bi-partite and multi-partite pure and mixed states.…

Quantum Physics · Physics 2009-05-18 Tzu-Chieh Wei

In a quantum change point problem, a source emitting particles in a fixed quantum state (default) switches to a different state at some stage, and the objective is to identify when the change happened by measuring a sequence of particles…

Quantum Physics · Physics 2024-04-11 Abhishek Banerjee , Pratapaditya Bej , Somshubhro Bandyopadhyay

Two systems whose correlations cannot be classically accounted for display the simplest instance of quantum entanglement. Although this two-party association has caused a revolution in the foundations and uses of quantum mechanics, genuine…

Quantum Physics · Physics 2017-07-26 M. G. M. Moreno , Fernando Parisio