Ultracold system

Concurrently, the world of ultracold systems has expanded its boundaries during the last decade to encompass ultracold, three-dimensional, large hnite systems [e.g., ( He)jy clusters (N = 2-10" ), and ( He)jy clusters (N = 25-10 )] in the temperature range of T = 0.1-2.2 K [6-11, 50-78], finite optical molasses in laser irradiated ultracold atomic gases in the temperature range of 10-100 pK [79], as well as finite Bose-Einstein condensates in the temperature range of 10-100 nK [14, 80],... 

In what follows we shall focus on some unique properties and features of finite, large ultracold systems, which can be traced to (a) quantum effects of zero-point energy and kinetic energy for the light constituent clusters (classes 1, 2, and 3) and (b) permutation symmetry effects in all systems (classes 1-6) considered herein. 

Another characterization of zero-point energy effects pertains to the increase in the actual average volume vq occupied by a particle in the ultracold system, relative to the reference volume v that the particles would occupy in a classical lattice. For nearly classical and for quantum clusters we have Vc = [11],... 

From Finite Ultracold Systems to the Bulk. The general features of packing, structure and thermodynamic properties, as well as the elementary excitation spectrum of large finite systems, converge to those of the corresponding bulk material for sufficiently large quantum clusters and ultracold clouds. 

The foregoing analysis [264] reflects on novel features of collective nuclear dynamics in finite ultracold systems. This leads to the concept of macroscopic tunneling [255, 265, 266]. The WKB approximation used [255, 265] for the macroscopic tunneling rate F (expressed in atoms/s) is... 

In parallel with the study of the control of atomic and molecular systems, "quantum engineering" of light itself has also been extensively investigated [114, 131, 132]. These studies have been aided by the availability of ultracold systems and advances in solid-state electronics. In particular, numerous nonclassical light states with squeezed fluctuations of observables have been constructed, and general methods for their preparation have been developed [133-136]. 

Heat added to an ice-water mixture melts some of the ice, but the mixture remains at 0 °C. Similarly, when an ice-water mixture in a freezer loses heat to the surroundings, the energy comes from some liquid water freezing, but the mixture remains at 0 °C until all the water has frozen. This behavior can be used to hold a chemical system at a fixed temperature. A temperature of 100 °C can be maintained by a boiling water bath, and an ice bath holds a system at 0 °C. Lower temperatures can be achieved with other substances. Dry ice maintains a temperature of -78 °C a bath of liquid nitrogen has a constant temperature of-196 °C (77 K) and liquid helium, which boils at 4.2 K, is used for research requiring ultracold temperatures. 

E. Energetics, Thermodynamics, Response, and Dynamics of Ultracold Finite Systems Size Effects on the Superfluid Transition in ( He) Finite Systems... 

Figure 1. The world of ultracold atomic, molecular, and cluster systems.

ULTRACOLD LARGE FINITE SYSTEMS BUILDING BRIDGES... 

Quantum Zero-Point Energy Effects for Ultracold Finite Systems... 

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