scholarly journals Spin squeezing of one-axis twisting model in the presence of phase dephasing

2013 ◽  
Vol 13 (3&4) ◽  
pp. 266-280
Author(s):  
Chen-Guang Ji ◽  
Yong-Chun Liu ◽  
Guang-Ri Jin
Keyword(s):  
Polar Angle ◽  
Spin Squeezing ◽  
Many Body ◽  
Initial State ◽  
Atomic Spin ◽  
Power Rule ◽  
The One ◽  
Bose Einstein ◽  
Dephasing Rate ◽  
The Ideal

We present a detailed analysis of spin squeezing of the one-axis twisting model with a many-body phase dephasing, which is induced by external field fluctuation in a two-mode Bose-Einstein condensates. Even in the presence of the dephasing, our analytical results show that the optimal initial state corresponds to a coherent spin state $|\theta_{0}, \phi_0\rangle$ with the polar angle $\theta_0=\pi/2$. If the dephasing rate $\gamma\ll S^{-1/3}$, where $S$ is total atomic spin, we find that the smallest value of squeezing parameter (i.e., the strongest squeezing) obeys the same scaling with the ideal one-axis twisting case, namely $\xi^2\propto S^{-2/3}$. While for a moderate dephasing, the achievable squeezing obeys the power rule $S^{-2/5}$, which is slightly worse than the ideal case. When the dephasing rate $\gamma>S^{1/2}$, we show that the squeezing is weak and neglectable.

scholarly journals Probing non-thermal density fluctuations in the one-dimensional Bose gas

2017 ◽  
Vol 3 (3) ◽  
Author(s):  
Jacopo De Nardis ◽  
Milosz Panfil ◽  
Andrea Gambassi ◽  
Leticia Cugliandolo ◽  
Robert Konik ◽  
...  
Keyword(s):  
Spatial Dimension ◽  
Bose Gas ◽  
Density Fluctuations ◽  
Dynamical Structure ◽  
Many Body ◽  
Initial State ◽  
One Dimensional ◽  
Fluctuation Dissipation ◽  
Quantum Integrable Models ◽  
The One

Quantum integrable models display a rich variety of non-thermal excited states with unusual properties. The most common way to probe them is by performing a quantum quench, i.e., by letting a many-body initial state unitarily evolve with an integrable Hamiltonian. At late times these systems are locally described by a generalized Gibbs ensemble with as many effective temperatures as their local conserved quantities. The experimental measurement of this macroscopic number of temperatures remains elusive. Here we show that they can be obtained for the Bose gas in one spatial dimension by probing the dynamical structure factor of the system after the quench and by employing a generalized fluctuation-dissipation theorem that we provide. Our procedure allows us to completely reconstruct the stationary state of a quantum integrable system from state-of-the-art experimental observations.

scholarly journals Entropy Production Within a Pulsed Bose–Einstein Condensate

2016 ◽  
Vol 71 (10) ◽  
pp. 875-881 ◽  
Author(s):  
Christoph Heinisch ◽  
Martin Holthaus
Keyword(s):  
Einstein Condensate ◽  
Many Body ◽  
Initial State ◽  
Site Model ◽  
Bose Einstein Condensate ◽  
Body Dynamics ◽  
Adiabatic Motion ◽  
The Many ◽  
Bose Einstein ◽  
Loss Of Coherence

AbstractWe suggest to subject anharmonically trapped Bose–Einstein condensates to sinusoidal forcing with a smooth, slowly changing envelope, and to measure the coherence of the system after such pulses. In a series of measurements with successively increased maximum forcing strength, one then expects an adiabatic return of the condensate to its initial state as long as the pulses remain sufficiently weak. In contrast, once the maximum driving amplitude exceeds a certain critical value there should be a drastic loss of coherence, reflecting significant heating induced by the pulse. This predicted experimental signature is traced to the loss of an effective adiabatic invariant, and to the ensuing breakdown of adiabatic motion of the system’s Floquet state when the many-body dynamics become chaotic. Our scenario is illustrated with the help of a two-site model of a forced bosonic Josephson junction, but should also hold for other, experimentally accessible configurations.

Academic Freedom and the Politics of Truth

2018 ◽  
Author(s):  
Michael P. Lynch
Keyword(s):  
Academic Freedom ◽  
Democratic Deliberation ◽  
Public Mind ◽  
Epistemic Practice ◽  
The Public ◽  
The One ◽  
Rational Inquiry ◽  
The Ideal

This chapter argues that academic freedom is justified because it is an inherently epistemic practice that serves the ideals of democracy. With Dewey, it is argued that “The one thing that is inherent and essential [to the idea of a university] is the ideal of truth.” But far from being apolitical, the value of pursuing truth and knowledge—the value that justifies academic freedom, both within and without the public mind—is a fundamental democratic value, and for three reasons: the practices of academic inquiry exemplify rational inquiry of the kind needed for democratic deliberation; those practices serve to train students to pursue that kind of inquiry; and those practices are important engines of democratic dissent.

Indications for Preservation Rhinoplasty: Avoiding Complications

2021 ◽  
Vol 37 (01) ◽  
pp. 045-052
Author(s):  
Mario Bazanelli Junqueira Ferraz ◽  
Guilherme Constante Preis Sella
Keyword(s):  
Nasal Bone ◽  
Nasal Dorsum ◽  
Ideal Candidate ◽  
Deviated Nose ◽  
Lateral Osteotomy ◽  
Upper Lateral Cartilage ◽  
High Radix ◽  
The One ◽  
Different Levels ◽  
The Ideal

AbstractNasal dorsal preservation surgery was described more than 100 years ago, but recently has gained prominence. Our objective is to show the surgical technique, the main indications and counterindications, and the complications. It is a technique that does not cause the detachment of the upper lateral cartilage (ULC) from the nasal septum, and has the main following sequence: preparation of the septum and its resection can be at different levels (high or low, i.e., SPAR [septum pyramidal adjustment and repositioning] A or B); preparation of the pyramid; transversal osteotomy; lateral osteotomy(s); and septopyramidal adjustment. The result is a nose with a lower radix than the original, a deprojection of the nasal dorsum tending to maintain its original shape; an increase in the interalar distance (IAD) and enlargement of the nasal middle ⅓; and loss of projection of the nasal tip and roundness of the nostrils. Thus, the ideal candidate is the one who benefits from such side effects, that is: tension nose, that is, high radix with projected dorsum, projected anterior nasal septal angle (ANSA), narrow middle ⅓, narrow IAD, thin nostrils and straight perpendicular plate of the ethmoid (PPE), and, depending on the characteristics, the deviated nose. The counterindications are low radix, irregularities in the nasal dorsum, ANSA lower than rhinion, and a wide middle ⅓. And the main stigmas are: a nose with a very low radix, middle ⅓ enlarged, residual hump, and saddling of the supratip area. Other issues of this technique are: the shape of the radix; the need or not to remove PPE; wide dorsum; irregular dorsum; ANSA lower than rhinion; weak cartilages; long nasal bone; deviated PPE; and obsessive patient. We conclude that this is a great technique for noses with characteristics suitable to it; care must be taken with the stigmas it can cause.

scholarly journals Entangling Lattice-Trapped Bosons with a Free Impurity: Impact on Stationary and Dynamical Properties

Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 290
Author(s):  
Maxim Pyzh ◽  
Kevin Keiler ◽  
Simeon I. Mistakidis ◽  
Peter Schmelcher
Keyword(s):  
Structural Changes ◽  
Many Body ◽  
Wide Range ◽  
Entropy Measures ◽  
Particle Level ◽  
The Many ◽  
The One ◽  
Tunneling Dynamics ◽  
The Individual ◽  
Trapped Bosons

We address the interplay of few lattice trapped bosons interacting with an impurity atom in a box potential. For the ground state, a classification is performed based on the fidelity allowing to quantify the susceptibility of the composite system to structural changes due to the intercomponent coupling. We analyze the overall response at the many-body level and contrast it to the single-particle level. By inspecting different entropy measures we capture the degree of entanglement and intraspecies correlations for a wide range of intra- and intercomponent interactions and lattice depths. We also spatially resolve the imprint of the entanglement on the one- and two-body density distributions showcasing that it accelerates the phase separation process or acts against spatial localization for repulsive and attractive intercomponent interactions, respectively. The many-body effects on the tunneling dynamics of the individual components, resulting from their counterflow, are also discussed. The tunneling period of the impurity is very sensitive to the value of the impurity-medium coupling due to its effective dressing by the few-body medium. Our work provides implications for engineering localized structures in correlated impurity settings using species selective optical potentials.

scholarly journals Derivation of the Landau–Pekar Equations in a Many-Body Mean-Field Limit

2021 ◽  
Vol 240 (1) ◽  
pp. 383-417
Author(s):  
Nikolai Leopold ◽  
David Mitrouskas ◽  
Robert Seiringer
Keyword(s):  
Mean Field ◽  
Einstein Condensate ◽  
Back Reaction ◽  
Many Body ◽  
Field Limit ◽  
Mean Field Limit ◽  
Phonon Field ◽  
Bose Einstein Condensate ◽  
Weakly Couple ◽  
Bose Einstein

AbstractWe consider the Fröhlich Hamiltonian in a mean-field limit where many bosonic particles weakly couple to the quantized phonon field. For large particle numbers and a suitably small coupling, we show that the dynamics of the system is approximately described by the Landau–Pekar equations. These describe a Bose–Einstein condensate interacting with a classical polarization field, whose dynamics is effected by the condensate, i.e., the back-reaction of the phonons that are created by the particles during the time evolution is of leading order.

scholarly journals Two-phase CFD simulation of the monodyspersed suspension hydraulic behaviour in the tank apparatus from a circulatory pipe

2008 ◽  
Vol 10 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Roch Plewik ◽  
Piotr Synowiec ◽  
Janusz Wójcik
Keyword(s):  
Cfd Simulation ◽  
Fluidised Bed ◽  
Cfd Simulations ◽  
Two Phase ◽  
Hydraulic Behaviour ◽  
Hydraulic Conditions ◽  
The One ◽  
Cfd Method ◽  
Multi Phase ◽  
The Ideal

Two-phase CFD simulation of the monodyspersed suspension hydraulic behaviour in the tank apparatus from a circulatory pipe The hydrodynamics in fluidized-bed crystallizers is studied by CFD method. The simulations were performed by a commercial packet of computational fluid dynamics Fluent 6.x. For the one-phase modelling (15), a standard k-ε model was applied. In the case of the two-phase flows the Eulerian multi-phase model with a standard k-ε method, aided by the k-ε dispersed model for viscosity, has been used respectively. The collected data put a new light on the suspension flow behaviour in the annular zone of the fluidised bed crystallizer. From the presented here CFD simulations, it clearly issues that the real hydraulic conditions in the fluidised bed crystallizers are far from the ideal ones.

scholarly journals Undecidability in quantum thermalization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Naoto Shiraishi ◽  
Keiji Matsumoto
Keyword(s):  
Turing Machine ◽  
Thermal Equilibrium ◽  
General Theorem ◽  
Nearest Neighbour ◽  
Many Body ◽  
Initial State ◽  
One Dimensional ◽  
Universal Turing Machine ◽  
Many Body Systems ◽  
Neighbour Interaction

AbstractThe investigation of thermalization in isolated quantum many-body systems has a long history, dating back to the time of developing statistical mechanics. Most quantum many-body systems in nature are considered to thermalize, while some never achieve thermal equilibrium. The central problem is to clarify whether a given system thermalizes, which has been addressed previously, but not resolved. Here, we show that this problem is undecidable. The resulting undecidability even applies when the system is restricted to one-dimensional shift-invariant systems with nearest-neighbour interaction, and the initial state is a fixed product state. We construct a family of Hamiltonians encoding dynamics of a reversible universal Turing machine, where the fate of a relaxation process changes considerably depending on whether the Turing machine halts. Our result indicates that there is no general theorem, algorithm, or systematic procedure determining the presence or absence of thermalization in any given Hamiltonian.

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