Abstract There are an increasing number of experimental scenarios where near-resonant light is applied to atoms tightly trapped in far off-resonant optical fields, such as for quantum optics ...applications or for atom imaging. Oftentimes, the electronic ground and excited states involved in the optical transition experience unequal trapping potentials. Here, we systematically analyze the effects of unequal trapping on near-resonant atom–light interactions. In particular, we identify regimes where such trapping can lead to significant excess heating compared to atoms in state-independent potentials, and a reduction of total and elastic scattering cross sections associated with a decreased atom–photon interaction efficiency. Understanding these effects can be valuable for achieving maximum efficiency in quantum optics experiments or atom imaging setups, where efficient atom–light interactions on resonance are desired, but achieving equal trapping is not feasible.
We investigate interference properties of a trapped atom interferometer where two symmetric optical dipole traps (ODTs) act as the atomic wave-packets splitter and combiner with internal state ...labelling. After the preparation of initial superposition states, the atomic wave-packet is adiabatically split and moves into two spatially separate asymmetric ODTs. The atomic wave-packets in two ODTs are then adiabatically recombined after a duration of free evolving in traps, completing the interference cycle of this atom interferometer. We show that the interferogram exhibits a series of periodic revivals in interference visibility. Furthermore, the revival period decreases as the asymmetry of two dipole potentials increases. By introducing an echo sequence to the interferometer, we show that while the echo effect is not influenced by the asymmetry of the two ODTs, the onset of periodic revivals changes by the echo sequence. Our study provides an effective method to cancel or compensate the phase shift caused by position and time correlated force.
Abstract
We investigate time-domain optics for atomic quantum matter. Within a matter-wave analog of the thin-lens formalism, we study optical lenses of different shapes and refractive powers to ...precisely control the dispersion of Bose–Einstein condensates. Anharmonicities of the lensing potential are incorporated in the formalism with a decomposition of the center-of-mass motion and expansion of the atoms, allowing to probe the lensing potential with micrometer resolution. By arranging two lenses in time formed by the potentials of an optical dipole trap and an atom-chip trap, we realize a magneto-optical matter-wave telescope. We employ this hybrid telescope to manipulate the expansion and aspect ratio of the ensembles. The experimental results are compared to numerical simulations that involve Gaussian shaped potentials to accommodate lens shapes beyond the harmonic approximation.
We consider the cold bosonic ensemble trapped by a helical interference pattern in the optical loop scheme. This rotating helical potential is produced by the two slightly detuned counter-propagating ...Laguerre–Gaussian laser beams with counter-directed orbital angular momenta ±ℓℏ. The detuning δω may occur due to rotational Doppler effect. The superfluid hydrodynamics is analyzed for the large number of trapped atoms in Thomas–Fermi approximation. For the highly elongated trap the Gross–Pitaevskii equation is solved in a slowly varying envelope approximation. The speed of axial translation and angular momenta of interacting atomic cloud are evaluated. In the T→0 limit the angular momentum of the helical cloud is expected to be zero while toroidal trapping geometry leads to 2ℓℏ angular momentum per trapped atom.
► Counter propagating detuned Laguerre–Gaussian laser beams. ► Superfluid motion in rotating helical trap. ► Orbital angular momentum of rotating atomic cloud.
Abstract
The lifetime of a gas of
6
Li atoms in a large hollow optical dipole trap formed by radiation with a frequency detuned by 4 or 2 GHz upward from resonance is measured. The trap has the shape ...of a thin-walled cylinder with flat bases and a volume of ∼1 mm
3
. The main mechanism responsible for the loss of atoms is heating due to Rayleigh scattering. The influence of collisions of atoms with the background gas and with each other on the measured lifetime is negligible.
The trapping of single atoms in optical dipole traps is widely used in experiments on the implementation of quantum processors based on neutral atoms, and studying interatomic interactions. ...Typically, such experiments employ lenses with a large numerical aperture (NA > 0.5), highly sensitive EMCCD cameras, or photon counters. In this work, we demonstrate trapping and detection of single rubidium atoms using a long-focus objective lens with a numerical aperture NA = 0.172 and a FLir Tau CNV sCMOS camera.
Application of Maslov’s asymptotic methods to equations that arise in the theory of optical lattices was considered. The occurrence of a small parameter in the Schrödinger equations with potentials ...of three-dimensional and controlled optical lattice was investigated and the conditions of application of Maslov’s asymptotic methods for solving these equations was determined. Consideration of different conditions imposed on the parameters in these potentials led to the use of two different methods for solving the arising equations: Maslov’s method of a complex germ and Maslov’s operator-valued method of a complex germ. Expressions that can be used to calculate the desired characteristics of the atomic systems under consideration in optical lattices were derived.
We describe the realization of Bose—Einstein condensates (BEC) of ⁸⁷Rb atoms with relatively large number of atoms at high density, in laser-optical traps in our laboratory. Ştarting from a giant ...magneto-optical trap containing nearly 10¹⁰ atoms, we transfer about 5 x 10⁷ atoms into the optical dipole trap formed by crossing two high-power focused CO₂ laser beams. BEC containing about 10⁵ atoms was produced by forced evaporative cooling of the atomic sample in the crossed optical trap down to about 140 nK, in just about a second. The BEC was also produced in a 1D optical lattice formed by the standing wave of a retro-reflected focused CO₂ laser beam, with about 80,000 atoms in the condensate. Effects of mean-field interaction characteristic of BEC were observed in the expansion dynamics of the condensate. We discuss both the techniques and the innovations that enabled the efficient execution of the multiple steps involved in producing the BEC, starting from a thermal sample of rubidium gas.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
We present an optical trap for atoms, which we have developed, for precision spectroscopy measurements. Cold atoms are captured in a dark region of space inside a blue-detuned hollow laser beam ...formed by an axicon. We analyze the light potential in a ray optics picture and experimentally demonstrate trapping of laser-cooled metastable xenon atoms. (Author)
Thermally stimulated luminescence (TSL) study of high purity carbazole crystals revealed the presence of the shallow traps for charge-carriers, which were interpreted in terms of dipole traps. A ...model that attributes these dipole traps to the orientational defects formed by a molecule of the crystal rotated by 180° along the long in-plane axis compared to the neighbor molecules has been suggested. Charge-carrier traps arise due to electrostatic interaction of the carrier with the permanent dipole moment of reoriented molecule. The depths of trapping states established on the molecules of the crystal neighboring one, two and three reoriented molecules have been calculated. The results of the calculations are in good agreement with the depths of the dipole traps obtained by fractional TSL technique.
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