Cold atoms

Over two hundred years ago the work of Charles and Gay-Lussac led to the suspicion that an absolute low temperature exists for matter. In recent years scientists have come very close to cooling matter to 0 K. The latest low-temperature record was achieved at the University of Colorado in Boulder when a team of scientists led by Carl Wieman reported that they had cooled a sample containing 2 X 107 cesium atoms to 1.1 X 10-6 K, about one-millionth of a degree above absolute zero. This record-low temperature was achieved by a technique known as laser cooling, in which a laser beam is directed against a beam of individual atoms, dramatically slowing the movement of the 

Trapping atoms at these extremely low temperatures for several seconds should allow the study of low-energy collisions, the ways that atoms attract each other to form aggregates, and of other properties that would provide tests of the fundamental theories of matter.  

These relationships showing how the volume of a gas depends on pressure, temperature, and number of moles of gas present can be combined as follows  

The ideal gas law is an equation of state for a gas, where the state of the gas is its condition at a given time. A particular state of a gas is described by its pressure, volume, temperature, and number of moles. Knowledge of any three of these properties is enough to completely define the state of a gas, since the fourth property can then be determined from the equation for the ideal gas law. 

The ideal gas law is often used to calculate the changes that will occur when the conditions of a gas are changed, as illustrated below. 

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Early experiments witli MOT-trapped atoms were carried out by initially slowing an atomic beam to load tire trap [20, 21]. Later, a continuous uncooled source was used for tliat purjDose, suggesting tliat tire trap could be loaded witli tire slow atoms of a room-temperature vapour [22]. The next advance in tire development of magneto-optical trapping was tire introduction of tire vapour-cell magneto-optical trap (VCMOT). This variation captures cold atoms directly from the low-velocity edge of tire Maxwell-Boltzmann distribution always present in a cell... 

Morinaga M, Yasuda M, Kishimoto T and Shimizu F 1996 Holographic manipulation of a cold atomic beam Phys.Rev.Lett. 77 802-5... 

Suominen K-A 1996 Theories for cold atomic collisions in light fields J.Phys.B At.Mol.Opt.Phys. 29 5981-6007... 

Cold atom gyroscope and application in space HYPER project... 

Laser cooling can efficiently reduce the velocity of the atoms but cannot circumvent the acceleration due to gravity. On the ground the 1-g gravity level sets clear limitations to the ultimate sensitivities. The HYPER project (Hyper precision cold atom interferometry in space) will follow precisely this line and will benefit from the space environment, which enables very long interaction time (few seconds) and low spurious vibrational level. The sensitivity of the atomic interferometer can achieve few 10 rad.s. Hz to rotation and to acceleration. This very sensitive and accurate apparatus... 

Fig. 13.23 (a) Transmission power of microtoroid resonator near the condition of critical coupling (inset shows the MNF/microtoroid sensor), (b) Single photon counting events C(t) as a function of time t after the release of the cold atom cloud at t 0. Reprinted from Ref. 48 with permission. 2008 Nature Publishing Group... 

E. Torrontegui, X. Chen, M. Modugno, A. Ruschhaupt, D. Guery-OdeUn, and I. G. Muga. Fast transitionless expansion of cold atoms in optical Gaussian-beam traps. Phys. Rev. A, 85(3) 033605-033613(2012). 

Rather than attempting to cool warm molecules one can try to synthesize cold molecules by associating cold atoms. The molecules thus formed are expected to maintain the translational temperature of the recombining atoms because the center-of-mass motion remains unchanged in the association process (save for the little. momentum imparted by the photon). This idea was first proposed by Julienne and j co-workers [343, 344] who envisioned a multistep association, first involving the continuum-to-bound excitation of translational continuum states of cold trapped. atoms to an excited vibrational level in an excited electronic molecular state. This step was followed by bound-bound spontaneous emission to the ground electronic state. (I... 

With only one exception, every experiment on BEC has employed laser cooling and trapping methods to create a gas of cold atoms. The exception is hydrogen. The recoil energy of hydrogen is so large that the gas cannot be cooled below a few millikelvin, with densities far from the transition. (The Amsterdam group... 

O Dwyer C, Gay G, Viaria de Lesegno B et al (2005) Advancing atomic nanolithography cold atomic Cs beam exposure of alkanethiol self assembled monolayers. J Phys Conf Ser 19 109-117... 

S. Zhang, A. Clairon, N. Dimarcq, P. Petit, A. Mann, A. Luiten, S. Chang, and C. Salomon Cold Atom Clocks on Earth and in Space . In Frequency Measurement and Control, ed. by A.N. Luiten (Springer, Berlin, Heidelberg 2000), pp. 131-153... 

This part is concerned with the quantum dynamics of molecules and ensembles of trapped cold atoms and the effect of internal-translational entanglement on interference and diffraction ... 

Bose condensates, trapped cold atoms, and cold Rydberg gases. 

An ensemble of cold Rydberg atoms is easily obtained after laser excitation of a cold atomic cloud, as those performed in a Gs or lib vapor-cell magnetooptical trap, at a temperature of 135 /jK or 300 fiK respectively. In the case of cesium (for the experiments performed at Laboratoire Aime Cotton) or rubidium (for the experiment performed at the University of Virginia), the atoms p-excited by the cooling lasers are Rydberg-excited by using a laser pulse provided by a dye laser pumped by the third harmonic of a Nd YAG laser... 

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