199 research outputs found
Spectroscopy of atomic rubidium at 500 bar buffer gas pressure: approaching the thermal equilibrium of dressed atom-light states
We have recorded fluorescence spectra of the atomic rubidium D-lines in the
presence of several hundreds of bars buffer gas pressure. With additional
saturation broadening a spectral linewidth comparable to the thermal energy of
the atoms in the heated gas cell is achieved. An intensity-dependent blue
asymmetry of the spectra is observed, which becomes increasingly pronounced
when extrapolating to infinitely high light intensity. We interpret our results
as evidence for the dressed (coupled atom-light) states to approach thermal
equilibrium.Comment: 4 page
Coherent, multi-heterodyne spectroscopy using stabilized optical frequency combs
The broadband, coherent nature of narrow-linewidth fiber frequency combs is
exploited to measure the full complex spectrum of a molecular gas through
multi-heterodyne spectroscopy. We measure the absorption and phase shift
experienced by each of 155,000 individual frequency comb lines, spaced by 100
MHz and spanning from 1495 nm to 1620 nm, after passing through a hydrogen
cyanide gas. The measured phase spectrum agrees with Kramers-Kronig
transformation of the absorption spectrum. This technique can provide a full
complex spectrum rapidly, over wide bandwidths, and with hertz-level accuracy.Comment: 4 pages, 3 figure
Thermalization via Heat Radiation of an Individual Object Thinner than the Thermal Wavelength
Modeling and investigating the thermalization of microscopic objects with
arbitrary shape from first principles is of fundamental interest and may lead
to technical applications. Here, we study, over a large temperature range, the
thermalization dynamics due to far-field heat radiation of an individual,
deterministically produced silica fiber with a predetermined shape and a
diameter smaller than the thermal wavelength. The temperature change of the
subwavelength-diameter fiber is determined through a measurement of its optical
path length in conjunction with an ab initio thermodynamic model of the fiber
structure. Our results show excellent agreement with a theoretical model that
considers heat radiation as a volumetric effect and takes the emitter shape and
size relative to the emission wavelength into account
Spectroscopy of a narrow-line laser cooling transition in atomic dysprosium
The laser cooling and trapping of ultracold neutral dysprosium has been
recently demonstrated using the broad, open 421-nm cycling transition.
Narrow-line magneto-optical trapping of Dy on longer wavelength transitions
would enable the preparation of ultracold Dy samples suitable for loading
optical dipole traps and subsequent evaporative cooling. We have identified the
closed 741-nm cycling transition as a candidate for the narrow-line cooling of
Dy. We present experimental data on the isotope shifts, the hyperfine constants
A and B, and the decay rate of the 741-nm transition. In addition, we report a
measurement of the 421-nm transition's linewidth, which agrees with previous
measurements. We summarize the laser cooling characteristics of these
transitions as well as other narrow cycling transitions that may prove useful
for cooling Dy.Comment: 6+ pages, 5 figures, 5 table
Quantum Computation with Diatomic Bits in Optical Lattices
We propose a scheme for scalable and universal quantum computation using
diatomic bits with conditional dipole-dipole interaction, trapped within an
optical lattice. The qubit states are encoded by the scattering state and the
bound heteronuclear molecular state of two ultracold atoms per site. The
conditional dipole-dipole interaction appears between neighboring bits when
they both occupy the molecular state. The realization of a universal set of
quantum logic gates, which is composed of single-bit operations and a two-bit
controlled-NOT gate, is presented. The readout method is also discussed.Comment: 5 pages, 1 eps figure, accepted for publication in Phys. Rev.
Laser-modified one- and two-photon absorption:Expanding the scope of optical nonlinearity
It is shown that conventional one-photon and two-photon absorption processes can be made subject to nonlinear optical control, in each case significantly modifying the efficiency of absorption, through the effect of a secondary, off-resonant stimulus laser beam. The mechanistic origin of these laser-modified absorption processes, in which the stimulus beam emerges unchanged, is traced to higher-order terms in standard perturbation treatments. These normally insignificant terms become unusually prominent when the secondary optical stimulus is moderately intense. Employing a quantum formulation, the effects of the stimulus beam on one-photon and two-photon absorption are analyzed, and calculations are performed to determine the degree of absorption enhancement, and the form of spectral manifestation, under various laser intensities. The implications of differences in selection rules are also considered and exemplified, leading to the identification of dark states that can be populated as a result of laser-modified absorption. Attention is also drawn to the possibility of quantum nondemolition measurements, based on such a form of optical nonlinearity
Velocity-selective sublevel resonance of atoms with an array of current-carrying wires
Resonance transitions between the Zeeman sublevels of optically-polarized Rb
atoms traveling through a spatially periodic magnetic field are investigated in
a radio-frequency (rf) range of sub-MHz. The atomic motion induces the
resonance when the Zeeman splitting is equal to the frequency at which the
moving atoms feel the magnetic field oscillating. Additional temporal
oscillation of the spatially periodic field splits a motion-induced resonance
peak into two by an amount of this oscillation frequency. At higher oscillation
frequencies, it is more suitable to consider that the resonance is mainly
driven by the temporal field oscillation, with its velocity-dependence or
Doppler shift caused by the atomic motion through the periodic field. A
theoretical description of motion-induced resonance is also given, with
emphasis on the translational energy change associated with the internal
transition.Comment: 7 pages, 3 figures, final versio
Global analysis of data on the spin-orbit coupled and states of Cs2
We present experimentally derived potential curves and spin-orbit interaction
functions for the strongly perturbed and
states of the cesium dimer. The results are based on data from several sources.
Laser-induced fluorescence Fourier transform spectroscopy (LIF FTS) was used
some time ago in the Laboratoire Aim\'{e} Cotton primarily to study the state. More recent work at Tsinghua University provides
information from moderate resolution spectroscopy on the lowest levels of the
states as well as additional high resolution data. From
Innsbruck University, we have precision data obtained with cold Cs
molecules. Recent data from Temple University was obtained using the
optical-optical double resonance polarization spectroscopy technique, and
finally, a group at the University of Latvia has added additional LIF FTS data.
In the Hamiltonian matrix, we have used analytic potentials (the Expanded Morse
Oscillator form) with both finite-difference (FD) coupled-channels and discrete
variable representation (DVR) calculations of the term values. Fitted diagonal
and off-diagonal spin-orbit functions are obtained and compared with {\it ab
initio} results from Temple and Moscow State universities
Absolute absorption line-shape measurements at the shot-noise limit
Here, we report a measurement scheme for determining an absorption profile with an accuracy imposed solely by photon shot noise. We demonstrate the power of this technique by measuring the absorption of cesium vapor with an uncertainty at the 2-ppm level. This extremely high signal-to-noise ratio allows us to directly observe the homogeneous line-shape component of the spectral profile, even in the presence of Doppler broadening, by measuring the spectral profile at a frequency detuning more than 200 natural linewidths from the line center. We then use this tool to discover an optically induced broadening process that is quite distinct from the well-known power broadening phenomenon
Theoretical study of the absorption spectra of the sodium dimer
Absorption of radiation from the sodium dimer molecular states correlating to
Na(3s)-Na(3s) is investigated theoretically. Vibrational bound and continuum
transitions from the singlet X Sigma-g+ state to the first excited singlet A
Sigma-u+ and singlet B Pi-u states and from the triplet a Sigma-u+ state to the
first excited triplet b Sigma-g+ and triplet c Pi-g states are studied
quantum-mechanically. Theoretical and experimental data are used to
characterize the molecular properties taking advantage of knowledge recently
obtained from ab initio calculations, spectroscopy, and ultra-cold atom
collision studies. The quantum-mechanical calculations are carried out for
temperatures in the range from 500 to 3000 K and are compared with previous
calculations and measurements where available.Comment: 19 pages, 8 figures, revtex, eps
- …