arXiv subjects

Lene Vestergaard Hau

Publications and source records attributed to Lene Vestergaard Hau.

10 recordsLinked to original sources

arXiv2010

Field Ionization of Cold Atoms near the Wall of a Single Carbon Nanotube

We observe the capture and field ionization of individual atoms near the side wall of a single suspended nanotube. Extremely large cross sections for ionization from an atomic beam are observed at modest voltages due to the nanotube's small radius and extended length. The effects of the field strength on both the atomic capture and the ionization process are clearly distinguished in the data, as are prompt and delayed ionizations related to the locations at which they occur. Efficient and sensitive neutral atom detectors can be based on the nanotube capture and wall ionization processes.

physics.atom-ph↗

arXiv2009

Creation of long-term coherent optical memory via controlled nonlinear interactions in Bose-Einstein condensates

A Bose-Einstein condensate confined in an optical dipole trap is used to generate long-term coherent memory for light, and storage times of more than one second are observed. Phase coherence of the condensate as well as controlled manipulations of elastic and inelastic atomic scattering processes are utilized to increase the storage fidelity by several orders of magnitude over previous schemes. The results have important applications for creation of long-distance quantum networks and for generation of entangled states of light and matter.

quant-ph↗

arXiv2009

Electro-Optical Nanotraps for Neutral Atoms

We propose a new class of nanoscale electro-optical traps for neutral atoms. A prototype is the toroidal trap created by a suspended, charged carbon nanotube decorated with a silver nanosphere dimer. An illuminating laser field, blue detuned from an atomic resonance frequency, is strongly focused by plasmons induced in the dimer and generates both a repulsive potential barrier near the nanostructure surface and a large viscous damping force that facilitates trap loading. Atoms with velocities of several meters per second may be loaded directly into the trap via spontaneous emission of just two photons.

physics.atom-ph↗

arXiv2004

Observation of Hybrid Soliton Vortex-Ring Structures in Bose-Einstein Condensates

We present the experimental discovery of compound structures comprising solitons and vortex rings in Bose-Einstein condensates (BECs). We examine both their creation via soliton-vortex collisions and their subsequent development, which is largely governed by the dynamics of interacting vortex rings. A theoretical model in three-dimensional (3D) cylindrical symmetry is also presented.

cond-mat.other↗

arXiv2004

Enhancement of microcavity lifetimes using highly dispersive materials

We show analytically, and numerically that highly-dispersive media can be used to drastically increase lifetimes of high-Q microresonators. In such a resonator, lifetime is limited either by undesired coupling to radiation, or by intrinsic absorption of the constituent materials. The presence of dispersion weakens coupling to the undesired radiation modes and also effectively reduces the material absorption.

physics.optics↗

arXiv2004

A High Flux Source of Cold Rubidium

We report the production of a continuous, slow, and cold beam of 87-Rb atoms with an unprecedented flux of 3.2 x 10^12 atoms/s and a temperature of a few milliKelvin. Hot atoms are emitted from a Rb candlestick atomic beam source and transversely cooled and collimated by a 20 cm long atomic collimator section, augmenting overall beam flux by a factor of 50. The atomic beam is then decelerated and longitudinally cooled by Zeeman slowing.

physics.atom-ph↗

arXiv2004

Ultra Low-Power All-Optical Switching

Using analytical modeling and detailed numerical simulations, we investigate properties of hybrid systems of Photonic Crystal micro-cavities which incorporate a highly non-linear Ultra Slow Light medium. We demonstrate that such systems, while being miniature in size (order wavelength), and integrable, could enable ultra-fast non-linear all-optical switching at single photon energy levels.

physics.optics↗

arXiv2001

Observation of Quantum Shock Waves Created with Ultra Compressed Slow Light Pulses in a Bose-Einstein Condensate

We have used an extension of our slow light technique to provide a method for inducing small density defects in a Bose-Einstein condensate. These sub-resolution, micron-sized defects evolve into large amplitude sound waves. We present an experimental observation and theoretical investigation of the resulting breakdown of superfluidity. We observe directly the decay of the narrow density defects into solitons, the onset of the `snake' instability, and the subsequent nucleation of vortices.

cond-mat.soft↗

arXiv1998

Cold Atoms and Creation of New States of Matter: Bose-Einstein Condensates, Kapitza States, and '2D Magnetic Hydrogen Atoms'

We have succeded in creating Bose-Einstein condensates with 2 million sodium atoms in a '4D' magnetic trap. We show the dynamic formation of a condensate as evaporative cooling proceeds. We also present a series of trap-release pictures clearly showing the distinctly different modes of expansion of condensate and thermal cloud. We further give two examples of wave guides for atomic de Broglie matter waves. One structure, the Kapitza wave guide, uses the interaction between an electrically polarizable atom and a charged wire. For stably bound orbits, a dynamical stabilization with time dependent potentials is necessary. This system, which can be tuned freely between classical and quantum regimes, shows chaotic behavior in the classical limit. The static counterpart of this wave guide leads to the introduction of the 'angular momentum quantum ladder' . The second wave guide structure is based upon the interaction between a current carrying wire and the magnetic dipole moment of an atom. A hydrogenic spectrum of bound states is derived through the concept of supersymmetry.

cond-mat↗

arXiv1998

Near Resonant Spatial Images of Confined Bose-Einstein Condensates in the '4D' Magnetic Bottle

We present quantitative measurements of the spatial density profile of Bose-Einstein condensates of sodium atoms confined in a new '4D' magnetic bottle. The condensates are imaged in transmission with near resonant laser light. We demonstrate that the Thomas-Fermi surface of a condensate can be determined to better than 1%. More generally, we obtain excellent agreement with mean-field theory. We conclude that precision measurements of atomic scattering lengths and interactions between phase separated cold atoms in a harmonic trap can be measured with high precision using this method.

cond-mat↗