We have observed Bose-Einstein condensation of sodium atoms. The atoms were trapped in a novel trap that employed both magnetic and optical forces. Evaporative cooling increased the phase-space density by 6 orders magnitude within seven seconds. Condensates contained up to 5\ifmmode\times\else\texttimes\fi{}${10}^{5}$ at densities exceeding ${10}^{14}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. striking signature Bose was sudden appearance bimodal velocity distribution below critical temperature...

In 1924 the Indian physicist Satyendra Nath Bose sent Einstein a paper in which he derived Planck law for black-body radiation by treating photons as gas of identical particles. generalized Bose's theory to an ideal atoms or molecules number particles is conserved and, same year, predicted that at sufficiently low temperatures would become locked together lowest quantum state system. We now know this phenomenon, called Bose-Einstein condensation (BEC), only happens "bosons" – with total spin...

Interference between two freely expanding Bose-Einstein condensates has been observed. Two separated by ∼40 micrometers were created evaporatively cooling sodium atoms in a double-well potential formed magnetic and optical forces. High-contrast matter-wave interference fringes with period of ∼15 observed after switching off the letting expand for 40 milliseconds overlap. This demonstrates that Bose condensed are “laser-like”; is, they coherent show long-range correlations. These results have...

Quantized vortices play a key role in superfluidity and superconductivity. We have observed the formation of highly ordered vortex lattices rotating Bose-condensed gas. These triangular contained over 100 with lifetimes several seconds. Individual persisted up to 40 The could be generated wide range rotation frequencies trap geometries, shedding light on process. Our observation dislocations, irregular structure, dynamics indicates that gaseous Bose-Einstein condensates may model system for...

We have observed Bose-Einstein condensation of pairs fermionic atoms in an ultracold 6Li gas at magnetic fields above a Feshbach resonance, where no stable 6Li2 molecules would exist vacuum. accurately determined the position resonance to be 822+/-3 G. Molecular condensates were detected after fast field ramp, which transferred close distances into bound molecules. Condensate fractions as high 80% obtained. The large condensate are interpreted terms preexisting quasistable even two-body due...

We experimentally implement the Harper Hamiltonian for neutral particles in optical lattices using laser-assisted tunneling and a potential energy gradient provided by gravity or magnetic field gradients. This describes motion of charged strong fields. Laser-assisted processes are characterized studying expansion atoms lattice. The band structure this should display Hofstadter's butterfly. For fermions, scheme realize quantum Hall effect chiral edge states.

Bose-Einstein condensates of sodium atoms have been confined in an optical dipole trap using a single focused infrared laser beam. This eliminates the restrictions magnetic traps for further studies atom lasers and condensates. More than $5\ifmmode\times\else\texttimes\fi{}{10}^{6}$ condensed were transferred into trap. Densities up to $3\ifmmode\times\else\texttimes\fi{}{10}^{15}{\mathrm{cm}}^{\ensuremath{-}3}$ Bose obtained, allowing measurement three-body loss rate constant as...

Bose-Einstein condensates of sodium atoms have been prepared in optical and magnetic traps which the energy-level spacing one or two dimensions exceeds interaction energy between atoms, realizing lower dimensionality. The crossover into two-dimensional one-dimensional was observed by a change aspect ratio release converging to nonzero value when number trapped reduced.

We have observed Bose-Einstein condensation of molecules. When a spin mixture fermionic 6Li atoms was evaporatively cooled in an optical dipole trap near Feshbach resonance, the atomic gas converted into 6Li2 Below 600 nK, condensate up to 900 000 molecules identified by sudden onset bimodal density distribution. This realizes limit tightly bound fermion pairs crossover between BCS superfluidity and condensation.

Whether it occurs in superconductors, helium-3 or inside a neutron star, fermionic superfluidity requires pairing of fermions, particles with half-integer spin. For an equal mixture two states fermions ("spin up" and "spin down"), can be complete the entire system will become superfluid. When populations are unequal, not every particle find partner. Will nevertheless stay superfluid? Here we study this intriguing question unequal strongly interacting ultracold atoms. The superfluid region vs...

The lure of lower temperatures has attracted physicists for the past century, and with each advance towards absolute zero, new rich physics emerged. Laypeople may wonder why ‘‘freezing cold’’ is not cold enough. But imagine how many aspects nature we would miss if lived on surface sun. Without inventing refrigerators, only know gaseous matter never observe liquids or solids, beauty snowflakes. Cooling to normal earthly reveals these dramatically different states matter, but this beginning:...

We have demonstrated an output coupler for Bose condensed atoms in a magnetic trap. Short pulses of rf radiation were used to create condensates superposition trapped and untrapped hyperfine states. The fraction out-coupled was adjusted between 0% 100% by varying the amplitude radiation. This configuration produces coherent can be regarded as pulsed ``atom laser.''

Properties of a Bose-Einstein condensate were studied by stimulated, two-photon Bragg scattering. The high momentum and energy resolution this method allowed spectroscopic measurement the mean-field intrinsic uncertainty condensate. coherence length was shown to be equal its size. spectroscopy can used determine dynamic structure factor over wide range transfers.

Collective excitations of a dilute Bose condensate have been observed. These are analogous to phonons in superfluid helium. condensates were created by evaporatively cooling magnetically trapped sodium atoms. Excitations induced modulation the trapping potential, and detected as shape oscillations freely expanding condensates. The frequencies lowest modes agreed well with theoretical predictions based on mean-field theory. Before onset Bose-Einstein condensation, we observed sound waves...

Rayleigh scattering off a Bose-Einstein condensate was studied. Exposing an elongated to single off-resonant laser beam resulted in the observation of highly directional light and atoms. This collective is caused by coherent center-of-mass motion atoms condensate. A recoiling built up matter wave amplification.

We have studied dissipation in a Bose--Einstein condensed gas by moving blue detuned laser beam through the condensate at different velocities. Strong heating was observed only above critical velocity.

A new magneto-optical trap is demonstrated which confines atoms predominantly in a ``dark'' hyperfine level, that does not interact with the trapping light. This leads to much higher atomic densities as repulsive forces between due rescattered radiation are reduced and loss excited-state collisions diminished. In such trap, more than ${10}^{10}$ sodium have been confined approaching ${10}^{12}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$.

A trapped-atom interferometer was demonstrated using gaseous Bose-Einstein condensates coherently split by deforming an optical single-well potential into a double-well potential. The relative phase between the two determined from spatial of matter wave interference pattern formed upon releasing separated wells. Coherent evolution observed for held 13 microm up to 5 ms and controlled applying ac Stark shift potentials either condensates.

Bose-Einstein condensation (BEC) of an ideal gas is investigated for a finite number particles. In three dimensions, we find transition temperature which lower than in the thermodynamic limit. Lowering dimension increases and therefore favorable BEC. This contrast to standard result obtained limit states that BEC not possible in, e.g., one-dimensional (1D) harmonic potential. As result, 1D atom traps, such as radially tightly confining magnetic traps or optical dipole are promising studying...

Bose-Einstein condensation of sodium atoms has been observed in a novel ``cloverleaf'' trap. This trap combines tight confinement with excellent optical access, using only dc electromagnets. Evaporative cooling this produced condensates $5\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atoms, tenfold improvement over previous results. We measured the condensate fraction and repulsive mean-field energy, finding agreement theoretical predictions.