Atom confinement laser

The production and study of stationary waves for E = 0 and E - / 0 were subject to a series of experiments [32] where a gas of atoms confined in a cavity was crossed by different types of stationary waves originating from a laser. 

To achieve both laser cooling and entan ement, we need to provide a coupling between intonal and motional quantum states. This can be achieved with the application of inhomogeneous (classical) electromagnetic fields. For example, consider an atom confined in a 1-D harmonic potential. The atom s dipole moment is assumed to couple to an electric field (x,t) through the Hamiltonian... 

Figure 4 - Insert shows the effect of blocking the confining laser beams 15 ms after the YAG laser fires. The horizontal trace is the scattered 1ight level. The fraction of atoms remaining is plotted a function of the time-off period.

Epitaxial crystal growth methods such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) have advanced to the point that active regions of essentially arbitrary thicknesses can be prepared (see Thin films, film deposition techniques). Most semiconductors used for lasers are cubic crystals where the lattice constant, the dimension of the cube, is equal to two atomic plane distances. When the thickness of this layer is reduced to dimensions on the order of 0.01 )J.m, between 20 and 30 atomic plane distances, quantum mechanics is needed for an accurate description of the confined carrier energies (11). Such layers are called quantum wells and the lasers containing such layers in their active regions are known as quantum well lasers (12). 

Gas lasers are not unlike fluorescent light bulbs and neon signs. Gas is confined to a hollow tube, and electricity passing through it excites the atoms. The most common gas lasers use carbon dioxide, argon, and helium-neon. Gas lasers are relatively inexpensive and can produce very high-powered beams. 

Single atomic ions confined in radio frequency traps and cooled by laser beams (Figure 7.4a) formed the basis for the first proposal of a CNOT quantum gate with an explicit physical system [14]. The first experimental realization of a CNOT quantum gate was in fact demonstrated on a system inspired by this scheme [37]. In this proposal, two internal electronic states of alkaline-earth or transition metal ions (e.g. Ba2+ or Yb3+) define the qubit basis. These states have excellent coherence properties, with T2 and T2 in the range of seconds [15]. Each qubit can be... 

There are several preparative methods for the production of bare metal clusters including the fast flow reactor (PER), the fast flow tube reactor (FTR), the SIDT (24), the GIB (23), and a supersonic cluster beam source (SCBS) (198). Essentially, all of these methods are similar. The first process is to vaporize the metal sample producing atoms, clusters, and ions. Laser vaporization is generally favored although FAB or FIB may be used. The sample is located in a chamber or a tube and so vaporization generally takes place in a confined environment. An inert gas such as helium may be present in the vaporization source or may be pulsed in after the ionization process. 

Fig. 2. Schematic diagram of the apparatus. The superconducting magnetic coils create trapping potential that confines atoms near the focus of the 243 nm laser beam. The beam is focused to a 50 pm waist radius and retro-reflected to allow for Doppler-free excitation. After excitation, fluorescence is induced by an applied electric field. A small fraction of the 122 nm fluorescence photons are counted on a microchannel plate detector. Not shown is the trapping cell which surrounds the sample and is thermally anchored to a dilution refrigerator. The actual trap is longer and narrower than indicated in the diagram...

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