Nonclassical dynamics of Bose condensates in an optical lattice in the superfluid regime

A condensate in an optical lattice, prepared in the ground state of the superfluid regime, is stimulated first by suddenly increasing the optical lattice amplitude and then, after a waiting time, by abruptly decreasing this amplitude to its initial value. Thus the system is first taken to the Mott regime and then back to the initial superfluid regime. We show that, as a consequence of this nonadiabatic process, the system falls into a configuration far from equilibrium whose superfluid order parameter is described in terms of a particular superposition of Glauber coherent states that we derive. We also show that the classical equations of motion describing the time evolution of this system are inequivalent to the standard discrete nonlinear Schreodinger equations. By numerically integrating such equations with several initial conditions, we show that the system loses coherence, becoming insulating.Comment: 5 pages, 4 figure

Quantum correlations of two optical fields close to electromagnetically induced transparency

We show that three-level atoms excited by two cavity modes in a $\Lambda$ configuration close to electromagnetically induced transparency can produce strongly squeezed bright beams or correlated beams which can be used for quantum non demolition measurements. The input intensity is the experimental "knob" for tuning the system into a squeezer or a quantum non demolition device. The quantum correlations become ideal at a critical point characterized by the appearance of a switching behavior in the mean fields intensities. Our predictions, based on a realistic fully quantum 3-level model including cavity losses and spontaneous emission, allow direct comparison with future experiments.Comment: 4 pages, 5 figure

Entanglement properties of degenerate four-wave mixing of matter-waves in a periodic potential

In a recent experiment Campbell et al. [Phys. Rev. Lett. 96, 020406 (2006)] observed degenerate four-wave mixing of matter-waves in a one-dimensional optical lattice, a process with potential for generating entanglement among atoms. We analyse the essential quantum features of the experiment to show that entanglement is created between the quadratures of the two scattered atomic clouds and is a true many-body (rather than two-body) effect. We demonstrate a significant violation of entanglement inequalities that is robust to a moderate level of coherent seeding. The system is thus a promising candididate for generating macroscopically entangled atomic samples.Comment: 4 pages, 3 figure

To What Extend Does the Technology Disrupstion Affect the Sale of Smes Banana Chips Products in Bandar Lampung?

Small and Medium-Sized Enterprises (SMEs) in Indonesia, which is also known as Usaha Mikro Kecil dan Menengah (UMKM), play a significant role in determining national economic performance. Banana chips are the most well-known product in Bandar Lampung. As the provincial capital of Lampung Province, Bandar Lampung becomes the center of trade and services sector which is a vital sector of the downstream industry activity. One of the vital aspect in the downstream of Banana chips industry is selling. This study aims to examine the effect of disruptive technology on the sale of SMEs Banana Chips products in Bandar Lampung. This study conduct the quantitative approach by using multiple regression linear analysis. The findings show that the regression model of selling aspect has 0.594 in R2 value. It means that the regression model is able to represent the real condition about 59,4%. According to the model, among the 6 (six) predictor variables, the most-influencing variable on the sale of Banana chips products is online-based promotion

Bogoliubov dynamics of condensate collisions using the positive-P representation

We formulate the time-dependent Bogoliubov dynamics of colliding Bose-Einstein condensates in terms of a positive-P representation of the Bogoliubov field. We obtain stochastic evolution equations for the field which converge to the full Bogoliubov description as the number of realisations grows. The numerical effort grows linearly with the size of the computational lattice. We benchmark the efficiency and accuracy of our description against Wigner distribution and exact positive-P methods. We consider its regime of applicability, and show that it is the most efficient method in the common situation - when the total particle number in the system is insufficient for a truncated Wigner treatment.Comment: 9 pages. 5 figure

Evolution of the macroscopically entangled states in optical lattices

We consider dynamics of boson condensates in finite optical lattices under a slow external perturbation which brings the system to the unstable equilibrium. It is shown that quantum fluctuations drive the condensate into the maximally entangled state. We argue that the truncated Wigner approximation being a natural generalization of the Gross-Pitaevskii classical equations of motion is adequate to correctly describe the time evolution including both collapse and revival of the condensate.Comment: 14 pages, 10 figures, Discussion of reversibility of entanglement is adde

Detecting phonons and persistent currents in toroidal Bose-Einstein condensates by means of pattern formation

We theoretically investigate the dynamic properties of a Bose-Einstein condensate in a toroidal trap. A periodic modulation of the transverse confinement is shown to produce a density pattern due to parametric amplification of phonon pairs. By imaging the density distribution after free expansion one obtains i) a precise determination of the Bogoliubov spectrum and ii) a sensitive detection of quantized circulation in the torus. The parametric amplification is also sensitive to thermal and quantum fluctuations.Comment: 4 pages, 4 figures; new figures, revised version to appear as a Rapid Communication in Physical Review

Genuine phase diffusion of a Bose-Einstein condensate in the microcanonical ensemble: A classical field study

Within the classical field model, we find that the phase of a Bose-Einstein condensate undergoes a true diffusive motion in the microcanonical ensemble, the variance of the condensate phase change between time zero and time $t$ growing linearly in $t$. The phase diffusion coefficient obeys a simple scaling law in the double thermodynamic and Bogoliubov limit. We construct an approximate calculation of the diffusion coefficient, in fair agreement with the numerical results over the considered temperature range, and we extend this approximate calculation to the quantum field.Comment: 9 pages, 6 figure

Squeezing and entangling nuclear spins in helium 3

We present a realistic model for transferring the squeezing or the entanglement of optical field modes to the collective ground state nuclear spin of $^3$He using metastability exchange collisions. We discuss in detail the requirements for obtaining good quantum state transfer efficiency and study the possibility to readout the nuclear spin state optically