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We consider the bipartite entanglement entropy of ground states of extended quantum systems with a large degeneracy. Often, as when there is a spontaneously broken global Lie group symmetry, basis elements of the lowest-energy space form a…

Statistical Mechanics · Physics 2013-05-30 Olalla A. Castro-Alvaredo , Benjamin Doyon

The one-tangle and {\pi}-tangle are used to quantify the entanglement of a tripartite GHZ state in noninertial frames when the system interacts with a noisy environment in the form of phase damping, phase flip and bit flip channel. It is…

Quantum Physics · Physics 2013-02-14 Salman Khan

We find tight lower and upper bounds on the entanglement of a superposition of two bipartite states in terms of the entanglement of the two states constituting the superposition. Our upper bound is dramatically tighter than the one…

Quantum Physics · Physics 2009-11-13 Gilad Gour

Distilling highly entangled quantum states from weaker ones is a process that is crucial for efficient and long-distance quantum communication, and has implications for several other quantum information protocols. We introduce the notion of…

Quantum Physics · Physics 2017-10-17 Tamoghna Das , Asutosh Kumar , Amit Kumar Pal , Namrata Shukla , Aditi Sen De , Ujjwal Sen

Entanglement [1, 2] enables powerful new quantum technologies [3-8], but in real-world implementations, entangled states are often subject to decoherence and preparation errors. Entanglement distillation [9, 10] can often counteract these…

Quantum Physics · Physics 2010-09-24 Jonathan Lavoie , Rainer Kaltenbaek , Marco Piani , Kevin J. Resch

A model of discrete dynamics of entanglement of bipartite quantum state is considered. It involves a global unitary dynamics of the system and periodic actions of local bistochastic or decaying channel. For initially pure states the decay…

Quantum Physics · Physics 2009-11-06 Karol Zyczkowski , Pawel Horodecki , Michal Horodecki , Ryszard Horodecki

The evolution of the entanglement measure during Compton scattering is studied. Our analytical results show that the corresponding measure coincides with the concurrence of the two-qubit state arising after scattering. The state never…

We investigate how entangled inertial Unruh-DeWitt detectors are affected by interaction with a quantum field using a nonperturbative method. Inertial detectors in a $(3+1)$-dimensional Minkowski spacetime with instantaneous switching…

Quantum Physics · Physics 2021-12-28 Kensuke Gallock-Yoshimura , Robert B. Mann

Given a bipartite quantum state (in arbitrary dimension) and a decomposition of it as a superposition of two others, we find bounds on the entanglement of the superposition state in terms of the entanglement of the states being superposed.…

Quantum Physics · Physics 2009-11-11 Noah Linden , Sandu Popescu , John A. Smolin

Currently the entanglement of formation can be calculated analytically for mixed states in a $(2\otimes2)$-dimensional Hilbert space. For states in higher dimensional Hilbert space a closed formula for quantifying entanglement does not…

Quantum Physics · Physics 2015-05-28 F. Lastra , C. E. López , L. Roa , J. C. Retamal

One of the essential features of quantum mechanics is that most pairs of observables cannot be measured simultaneously. This phenomenon is most strongly manifested when observables are related to mutually unbiased bases. In this paper, we…

Quantum Physics · Physics 2015-05-27 M. Wiesniak , T. Paterek , A. Zeilinger

We calculate the entanglement of formation and the entanglement of distillation for arbitrary mixtures of the zero spin states on an arbitrary-dimensional bipartite Hilbert space. Such states are relevant to quantum black holes and to…

Quantum Physics · Physics 2007-05-23 Etera R. Livine , Daniel R. Terno

We give a topological classification of the evolution of entanglement, particularly the different ways the entanglement can disappear. Four categories exhaust all possibilities given the initial quantum state is entangled and the final one…

Quantum Physics · Physics 2012-04-11 Dong Zhou , Robert Joynt

Entanglement distillation refers to the task of transforming a collection of weakly entangled pairs into fewer highly entangled ones. It is a core ingredient in quantum repeater protocols, needed to transmit entanglement over arbitrary…

Quantum Physics · Physics 2016-01-20 Stephan Waeldchen , Janina Gertis , Earl T. Campbell , Jens Eisert

The disentangling effect of repeated applications of the bit flip channel (I\otimes\sigma_x) on bipartite qubit systems is analyzed. It is found that the rate of loss of entanglement is not uniform over all states. The distillable…

Quantum Physics · Physics 2007-05-23 Kovid Goyal

Relations between photon scattering, entanglement and multi-mode detection are investigated. We first establish a general framework in which one- and two-photon elastic scattering processes can be discussed, then we focus on the study of…

Quantum Physics · Physics 2009-11-10 A. Aiello , J. P. Woerdman

We report on ground state phases of a doped one-dimensional Hubbard model, which for large onsite interactions is governed by the $t$-$J$ Hamiltonian, where the extant entanglement is immutable under perturbative or sudden changes of system…

How entangled is a randomly chosen bipartite stabilizer state? We show that if the number of qubits each party holds is large the state will be close to maximally entangled with probability exponentially close to one. We provide a similar…

Quantum Physics · Physics 2007-05-23 Graeme Smith , Debbie Leung

We calculate the effect of polarization-dependent scattering by disorder on the degree of polarization-entanglement of two beams of radiation. Multi-mode detection converts an initially pure state into a mixed state with respect to the…

Quantum Physics · Physics 2007-05-23 J. L. van Velsen , C. W. J. Beenakker

We explore the relation between the rank of a bipartite density matrix and the existence of bound entanglement. We show a relation between the rank, marginal ranks, and distillability of a mixed state and use this to prove that any rank n…

Quantum Physics · Physics 2007-05-23 Pawel Horodecki , John A. Smolin , Barbara M. Terhal , Ashish V. Thapliyal