We simulate numerically the photodissociation of molecules into noncondensate atom pairs that accompanies photoassociation of an atomic Bose-Einstein condensate into a molecular condensate. Such rogue photodissociation sets a limit on the achievable rate of photoassociation. Given the atom density $\rho$ and mass $m$, the limit is approximately $6ħ{\rho }^{2/3}/m$.

We consider a two-component atomic gas illumined by two intersecting laser beams which induce Raman coupling between the components. This spatially periodic coupling modifies the dispersion relation of the gas. Properties of a Bose-Einstein condensate of such a gas are strongly affected by this modification. Using the quasiparticle excitation spectrum derived from a Bogoliubov transformation, the Landau critical velocity is found to be anisotropic and can be widely tuned by varying properties of the dressing laser beams.

We predict a direct and observable signature of the superfluid phase in a quantum Fermi gas, in a temperature regime already accessible in current experiments. We apply the theory of resonance superfluidity to a gas confined in a harmonic potential and demonstrate that a significant increase in density will be observed in the vicinity of the trap center.

Clock-comparison experiments conducted in space can provide access to many unmeasured coefficients for Lorentz and $\mathrm{CPT}$ violation. The orbital configuration of a satellite platform and the relatively large velocities attainable in a deep-space mission would permit a broad range of tests with Planck-scale sensitivity.

We report on a quantitative study of the growth process of ${}^{87}\mathrm{Rb}$ Bose-Einstein condensates. By continuous evaporative cooling we directly control the thermal cloud from which the condensate grows. We compare the experimental data with the results of a theoretical model based on quantum kinetic theory. We find quantitative agreement with theory for the situation of strong cooling, whereas in the weak cooling regime a distinctly different behavior is found in the experiment.

We show that stable Skyrmions exist in two-component atomic Bose-Einstein condensates, in the regime of phase separation. Using full three-dimensional simulations we find the stable Skyrmions with topological charges $Q=1\mathrm{}$ and 2, and compute their properties. With reference to these computations we suggest the salient features of an experimental setup in which they might realized.

We improve on the Popov theory for partially Bose-Einstein condensed atomic gases by treating the phase fluctuations exactly. As a result, the theory becomes valid in arbitrary dimensions and is able to describe the low-temperature crossover between three-, two-, and one-dimensional Bose gases, which is currently being explored experimentally. We consider both homogeneous and trapped Bose gases.

We calculate the phonon excitation spectrum in a zero-temperature dilute boson-fermion gaseous mixture. We show how the sound velocity changes due to the boson-fermion interaction, and we determine the dynamical stability regime of a homogeneous mixture. We identify a resonant phonon-exchange interaction between the fermions as the physical mechanism leading to the instability.

The dynamics of vortex lattices in stirred Bose-Einstein condensates have been studied at finite temperatures. The decay of the vortex lattice was observed nondestructively by monitoring the centrifugal distortions of the rotating condensate. The formation of the vortex lattice could be deduced from the increasing contrast of the vortex cores observed in ballistic expansion. In contrast to the decay, the formation of the vortex lattice is insensitive to temperature change.

A scheme for generating continuous beams of atoms in nonclassical or entangled quantum states is proposed and analyzed. For this the recently suggested transfer technique of quantum states from light fields to collective atomic excitation by stimulated Raman adiabatic passage [M. Fleischhauer and M. D. Lukin, Phys. Rev. Lett. 84, 5094 (2000)] is employed and extended to matter waves.

We propose an easily detectable signature of superfluidity in rotating, vortex-free gaseous Bose-Einstein condensates. We have studied the time evolution of the expansion of such a condensate after it is released from the confining trap. We find that if such a condensate is not initially rotating, then at some moment it will instantaneously achieve a circular cross section. If the condensate is initially rotating its irrotational flow and the conservation of angular momentum prevent the released condensate from attaining a circular cross section, since the instantaneous moment of inertia is then proportional to the asymmetry of this cross section.

We have observed the expansion of vortex-free, rotating Bose condensates after their sudden release from a slowly rotating anisotropic trap. Conservation of angular momentum, combined with the constraint of irrotational flow, cause the rotating condensate to expand in a distinctively different way to one released from a static (nonrotating) trap. This difference provides clear experimental evidence of the purely irrotational velocity field associated with a superfluid. We observed this behavior in absorption images taken along the rotation axis.

We study surface modes of the condensate in the presence of a rotating thermal cloud in an axisymmetric trap. By considering collisions that transfer atoms between the condensate and the noncondensate, we find that $m>\mathrm{}0\mathrm{}$ modes, which rotate in the same sense as the thermal cloud, damp less strongly than $m<\mathrm{}0\mathrm{}$ modes, where $m$ is the polarity of the excitation. We show that above a critical angular rotation frequency, equivalent to the Landau stability criterion, $m>\mathrm{}0\mathrm{}$ modes become dynamically unstable, leading to the possibility of vortex nucleation. We also generalize our stability analysis to treat the case where the stationary state of the condensate already possesses a single vortex.

We report the experimental realization of teleporting a one-particle entangled qubit. The qubit is physically implemented by a two-dimensional subspace of states of a mode of the electromagnetic field, specifically, the space spanned by the vacuum and the one-photon state. Our experiment follows the line suggested by Lee and Kim [Phys. Rev. A 63, 012305 (2000)] and Knill, Laflamme, and Milburn [Nature (London) 409, 46 (2001)]. An unprecedented large value of the teleportation “fidelity” has been attained: $F=(95.3\pm 0.6)\%$.

We observe counterintuitive spin segregation in an inhomogeneous sample of ultracold, noncondensed rubidium atoms in a magnetic trap. We use spatially selective microwave spectroscopy to verify a model that accounts for the differential forces on two internal spin states. In any simple understanding of the cloud dynamics, the forces are far too small to account for the dramatic transient spin polarizations observed. The underlying mechanism remains to be elucidated.

We consider an arbitrary Gaussian stationary process $X\left(T\right)$ with known correlator $C\left(T\right)$, sampled at discrete times $T_n=n\Delta T$. The probability that $(n+1\mathrm{})$ consecutive values of $X$ have the same sign decays as $P_n\sim \exp (-{\theta }_D{T}_n)$. We calculate the discrete persistence exponent ${\theta }_D$ as a series expansion in the correlator $C\left(\Delta T\right)$ up to fourteenth order, and extrapolate to $\Delta T=0\mathrm{}$ using constrained Padé approximants to obtain the continuum persistence exponent $\theta$. For the diffusion equation our results are in exceptionally good agreement with recent numerical estimates.

Cirel’son inequality states that the absolute value of the combination of quantum correlations appearing in the Clauser-Horne-Shimony-Holt (CHSH) inequality is bound by $2\sqrt{2}$. It is shown that the correlations of two qubits belonging to a three-qubit system can violate the CHSH inequality beyond $2\sqrt{2}$. Such a violation is not in conflict with Cirel’son’s inequality because it is based on postselected systems. The maximum allowed violation of the CHSH inequality, 4, can be achieved using a Greenberger-Horne-Zeilinger state.

Phonons with wave vector $q/ħ$ were optically imprinted into a Bose-Einstein condensate. Their momentum distribution was analyzed using Bragg spectroscopy with a high momentum transfer. The wave function of the phonons was shown to be a superposition of $+q$ and $-q$ free particle momentum states, in agreement with the Bogoliubov quasiparticle picture.

The spin dynamics of atomic Bose-Einstein condensates confined in a one-dimensional optical lattice is studied. The condensates at each lattice site behave like spin magnets that can interact with each other through both the light-induced dipole-dipole interaction and the static magnetic dipole-dipole interaction. We show how these site-to-site dipolar interactions can distort the ground-state spin orientations and lead to the excitation of spin waves. The dispersion relation of the spin waves is studied and possible detection schemes are proposed.

A general and an arbitrarily efficient scheme for entangling the spins (or any spinlike degree of freedom) of two independent uncorrelated identical particles by a combination of two particle interferometry and which way detection is formulated. It is shown that the same setup could be used to identify the quantum statistics of the incident particles from either the sign or the magnitude of measured spin correlations. Our setup also exhibits a curious complementarity between particle distinguishability and the amount of generated entanglement.