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A quantum state's entanglement across a bipartite cut can be quantified with entanglement entropy or, more generally, Schmidt norms. Using only Schmidt decompositions, we present a simple iterative algorithm to maximize Schmidt norms.…

Quantum Physics · Physics 2018-06-14 Robin Reuvers

In [J. C. Howell and J. A. Yeazell, Phys. Rev. A 62, 012102 (2000)], a proposal is made to generate entangled macroscopically distinguishable states of two spatially separated traveling optical modes. We model the decoherence due to light…

Quantum Physics · Physics 2016-04-26 J. Clausen , L. Knoell , D. -G. Welsch

Recent efforts have focused on characterizing the set of separable states that cannot be made entangled by any global unitary transformation. Here we characterize the set of states whose entanglement content cannot be increased under any…

Quantum Physics · Physics 2026-04-06 Jofre Abellanet-Vidal , Guillem Müller-Rigat , Albert Rico , Anna Sanpera

Entangled states play a fundamental role in Quantum Mechanics and are at the core of many contemporary applications, such as quantum communication and quantum computing. Therefore, determining whether a state is entangled or not is an…

Quantum Physics · Physics 2023-05-11 J. Cortés-Vega , J. F. Barra , L. Pereira , A. Delgado

We introduce geometric measures of entanglement for indistinguishable particles, which apply to mixed states, multipartite systems, and arbitrary dimensions. They are based on generalized (i.e., not necessarily finite) norms on the set of…

Quantum Physics · Physics 2015-07-17 Florian Sokoli , Burkhard Kümmerer

Entanglement measures quantify the amount of quantum entanglement that is contained in quantum states. Typically, different entanglement measures do not have to be partially ordered. The presence of a definite partial order between two…

Quantum Physics · Physics 2022-08-30 Danko D. Georgiev , Stanley P. Gudder

The state overlap, quantified via $\tr[\rho \sigma]$, is a metric widely used to assess the closeness between two quantum states $\rho$ and $\sigma$. Although global state overlap alone does not directly capture entanglement properties, we…

Quantum entanglement is a fascinating phenomenon, especially if it is observed at the macroscopic scale. Importantly, macroscopic quantum correlations can be revealed only by accurate measurement outcomes and strategies. Here, we formulate…

Quantum Physics · Physics 2012-11-22 Magdalena Stobińska , Falk Töppel , Pavel Sekatski , Maria V. Chekhova

Entanglement is a fundamental feature of quantum mechanics, considered a key resource in quantum information processing. Measuring entanglement is an essential step in a wide range of applied and foundational quantum experiments. When a…

We address joint photodetection as a method to discriminate between the classical correlations of a thermal beam divided by a beam splitter and the quantum entanglement of a twin-beam obtained by parametric downconversion. We show that for…

Quantum Physics · Physics 2009-11-11 A. Agliati , M. Bondani , A. Andreoni , G. De Cillis , M. G. A. Paris

The emission of entangled light from planar semiconductor microcavities is studied and the entanglement properties are analyzed and quantified. Phase-matching of the intra-cavity scattering dynamics for multiple pump beams or pulses,…

Quantum Physics · Physics 2015-06-05 D. Pagel , H. Fehske , J. Sperling , W. Vogel

We propose a simple and realizable method using a two-particle interferometer for the experimental measurement of pairwise entanglement, assuming some prior knowledge about the quantum state. The basic idea is that the properties of the…

Quantum Physics · Physics 2007-05-23 Jian-Ming Cai , Zheng-Wei Zhou , Guang-Can Guo

A sufficient condition for entanglement in two-mode continuous systems is constructed based on interference visibility and the uncertainty of the total particle number. The observables to be measured (particle numbers and particle number…

Quantum Physics · Physics 2007-05-23 Geza Toth , Christoph Simon , Juan Ignacio Cirac

We explore, both experimentally and theoretically, the propagation dynamics of spatially entangled photon pairs (biphotons). Characterization of entanglement is done via the Schmidt number, which is a universal measurement of the degree of…

Optics · Physics 2017-06-28 Matthew Reichert , Xiaohang Sun , Jason W. Fleischer

We report on criteria to detect entanglement between the light modes of two crossed optical cavities by analyzing the transverse deflection patterns of an atomic beam. The photon exchange between the modes and the atoms occurs around the…

We experimentally demonstrate polarization entanglement for squeezed vacuum pulses containing more than 10^5 photons. We also study photon-number entanglement by calculating the Schmidt number and measuring its operational counterpart.…

Quantum Physics · Physics 2012-11-16 Timur Sh. Iskhakov , Ivan N. Agafonov , Maria V. Chekhova , Gerd Leuchs

A deep understanding of quantum entanglement is vital for advancing quantum technologies. The strength of entanglement can be quantified by counting the degrees of freedom that are entangled, which results in a quantity called Schmidt…

Quantum Physics · Physics 2024-02-21 Robin Krebs , Mariami Gachechiladze

Entanglement can modify the interference patterns of multi-particle systems. We analyse, using the path integral formalism, a novel example of multi-particle interference and some unexplored aspects of this phenomenon by considering the…

Quantum Physics · Physics 2022-03-30 Pedro Sancho

Although the foundations of quantum and classical physics are much different, it is often difficult to pinpoint which features of a particular system are intrinsically "quantum". Perhapse, the most clear-cut distinction between "classical"…

Quantum Physics · Physics 2015-02-05 Piotr Szańkowski

In the standard geometric approach, the entanglement of a pure state is $\sin^2\theta$, where $\theta$ is the angle between the entangled state and the closest separable state of products of normalised qubit states. We consider here a…

Quantum Physics · Physics 2015-05-18 M. E. Carrington , R. Kobes , G. Kunstatter , D. Ostapchuk , G. Passante