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Jun 30, 2018
06/18

by
Anna M. Barry; F. Hajir; P. G. Kevrekidis

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In this work, we construct suitable generating functions for vortices of alternating signs in the realm of Bose-Einstein condensates. In addition to the vortex-vortex interaction included in earlier fluid dynamics constructions of such functions, the vortices here precess around the center of the trap. This results in the generating functions of the vortices of positive charge and of negative charge satisfying a modified, so-called, Tkachenko differential equation. From that equation, we...

Topics: Nonlinear Sciences, Quantum Gases, Mathematics, Pattern Formation and Solitons, Mathematical...

Source: http://arxiv.org/abs/1407.7965

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Jun 30, 2018
06/18

by
Bruno Rousseau; François Lapointe; Minh Nguyen; Maxime Biron; Etienne Gaufrès; Saman Choubak; Zheng Han; Vincent Bouchiat; Patrick Desjardins; Michel Côté; Richard Martel

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Herein, intervalley scattering is exploited to account for anomalous antiresonances in the infrared spectra of doped and disordered single layer graphene. We present infrared spectroscopy measurements of graphene grafted with iodophenyl moieties in both reflection microscopy and transmission configurations. Asymmetric transparency windows at energies corresponding to phonon modes near the {\Gamma} and K points are observed, in contrast to the featureless spectrum of pristine graphene. These...

Topics: Mesoscale and Nanoscale Physics, Materials Science, Condensed Matter

Source: http://arxiv.org/abs/1407.8141

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4.0

Jun 30, 2018
06/18

by
Issam Ibnouhsein; Fabio Costa; Alexei Grinbaum

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Entanglement is defined between subsystems of a quantum system, and at fixed time two regions of space can be viewed as two subsystems of a relativistic quantum field. The entropy of entanglement between such subsystems is ill-defined unless an ultraviolet cutoff is introduced, but it still diverges in the continuum limit. This behaviour is generic for arbitrary finite-energy states, hence a conceptual tension with the finite entanglement entropy typical of nonrelativistic quantum systems. We...

Topics: Quantum Physics, High Energy Physics - Theory

Source: http://arxiv.org/abs/1407.8050

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Jun 30, 2018
06/18

by
Jing Zhang; Yu-xi Liu; Re-Bing Wu; Kurt Jacobs; Sahin Kaya Ozdemir; Lan Yang; Tzyh-Jong Tarn; Franco Nori

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Quantum input-output theory plays a very important role for analyzing the dynamics of quantum systems, especially large-scale quantum networks. As an extension of the input-output formalism of Gardiner and Collet, we develop a new approach based on the quantum version of the Volterra series which can be used to analyze nonlinear quantum input-output dynamics. By this approach, we can ignore the internal dynamics of the quantum input-output system and represent the system dynamics by a series of...

Topic: Quantum Physics

Source: http://arxiv.org/abs/1407.8108

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3.0

Jun 30, 2018
06/18

by
John M. Myers; F. Hadi Madjid

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Quantum theory reflects within itself a separation of evidence from explanations. This separation leads to a known proof that: (1) no wave function can be determined uniquely by evidence, and (2) any chosen wave function requires a guess reaching beyond logic to things unforeseeable. Chosen wave functions are encoded into computer-mediated feedback essential to atomic clocks, including clocks that step computers through their phases of computation and clocks in space vehicles that supply...

Topics: Quantum Physics, General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1407.8020

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3.0

Jun 30, 2018
06/18

by
M. Zuppardo; J. P. Santos; G. De Chiara; M. Paternostro; F. L. Semiao; G. M. Palma

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We describe an apparatus designed to make non-demolition measurements on a Bose-Einstein condensate (BEC) trapped in a double-well optical cavity. This apparatus contains, as well as the bosonic gas and the trap, an optical cavity. We show how the interaction between the light and the atoms, under appropriate conditions, can allow for a weakly disturbing yet highly precise measurement of the population imbalance between the two wells and its variance. We show that the setting is well suited for...

Topics: Quantum Physics, Quantum Gases, Condensed Matter

Source: http://arxiv.org/abs/1407.8077

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Jun 30, 2018
06/18

by
Taras Verkholyak; Jozef Strecka; Frederic Mila; Kai P. Schmidt

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Exact ground states of a spin-1/2 Ising-Heisenberg model on the Shastry-Sutherland lattice with Heisenberg intra-dimer and Ising inter-dimer couplings are found by two independent rigorous procedures. The first method uses a unitary transformation to establish a mapping correspondence with an effective classical spin model, while the second method relies on the derivation of an effective hard-core boson model by continuous unitary transformations. Both methods lead to equivalent effective...

Topics: Statistical Mechanics, Condensed Matter

Source: http://arxiv.org/abs/1407.8229

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Jun 30, 2018
06/18

by
Yuancheng Fan; Fuli Zhang; Qian Zhao; Zeyong Wei; Hongqiang Li

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Coherent perfect absorber (CPA) was proposed as the time-reversed counterpart to laser: a resonator containing lossy medium instead of gain medium can absorb the coherent optical fields completely. Here, we exploit a monolayer graphene to realize the CPA in a non-resonant manner. It is found that quasi-CPA point exists in the terahertz regime for suspending monolayer graphene, and the CPA can be implemented with the assistant of proper phase modulation among two incident beams at the quasi-CPA...

Topics: Physics, Mesoscale and Nanoscale Physics, Optics, Materials Science, Condensed Matter

Source: http://arxiv.org/abs/1407.7961

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Jun 30, 2018
06/18

by
Yuchen Peng; Frank Gaitan

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Successful implementation of a fault-tolerant quantum computation on a system of qubits places severe demands on the hardware used to control the many-qubit state. It is known that an accuracy threshold $P_{a}$ exists for any quantum gate that is to be used in such a computation. Specifically, the error probability $P_{e}$ for such a gate must fall below the accuracy threshold: $P_{e} < P_{a}$. Estimates of $P_{a}$ vary widely, though $P_{a}\sim 10^{-4}$ has emerged as a challenging target...

Topics: Quantum Physics, Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1407.8074