339 research outputs found
Electromagnetically Induced Transparency from a Single Atom in Free Space
We report an absorption spectroscopy experiment and the observation of
electromagnetically induced transparency from a single trapped atom. We focus a
weak and narrowband Gaussian light beam onto an optically cooled Barium ion
using a high numerical aperture lens. Extinction of this beam is observed with
measured values of up to 1.3 %. We demonstrate electromagnetically induced
transparency of the ion by tuning a strong control beam over a two-photon
resonance in a three-level lambda-type system. The probe beam extinction is
inhibited by more than 75 % due to population trapping.Comment: 4 pages, 3 figure
Chirality distribution and transition energies of carbon nanotubes
From resonant Raman scattering on isolated nanotubes we obtained the optical
transition energies, the radial breathing mode frequency and Raman intensity of
both metallic and semiconducting tubes. We unambiguously assigned the chiral
index (n_1,n_2) of approximately 50 nanotubes based solely on a third-neighbor
tight-binding Kataura plot and find omega_RBM=214.4cm^-1nm/d+18.7cm^-1. In
contrast to luminescence experiments we observe all chiralities including
zig-zag tubes. The Raman intensities have a systematic chiral-angle dependence
confirming recent ab-initio calculations.Comment: 4 pages, to be published in Phys. Rev. Let
Interferometric thermometry of a single sub-Doppler cooled atom
Efficient self-interference of single-photons emitted by a sideband-cooled
Barium ion is demonstrated. First, the technical tools for performing efficient
coupling to the quadrupolar transition of a single Ba ion are
presented. We show efficient Rabi oscillations of the internal state of the ion
using a highly stabilized 1.76 fiber laser resonant with the
S-D transition. We then show sideband cooling of the ion's
motional modes and use it as a means to enhance the interference contrast of
the ion with its mirror-image to up to 90%. Last, we measure the dependence of
the self-interference contrast on the mean phonon number, thereby demonstrating
the potential of the set-up for single-atom thermometry close to the motional
ground state.Comment: 6 pages, 6 figure
Counter-Intuitive Vacuum-Stimulated Raman Scattering
Vacuum-stimulated Raman scattering in strongly coupled atom-cavity systems
allows one to generate free-running single photon pulses on demand. Most
properties of the emitted photons are well defined, provided spontaneous
emission processes do not contribute. Therefore, electronic excitation of the
atom must not occur, which is assured for a system adiabatically following a
dark state during the photon-generation process. We experimentally investigate
the conditions that must be met for adiabatic following in a time-of-flight
driven system, with atoms passing through a cavity and a pump beam oriented
transverse to the cavity axis. From our results, we infer the optimal intensity
and relative pump-beam position with respect to the cavity axis.Comment: 4 pages, 4 figure
Contacting single bundles of carbon nanotubes with alternating electric fields
Single bundles of carbon nanotubes have been selectively deposited from
suspensions onto sub-micron electrodes with alternating electric fields. We
explore the resulting contacts using several solvents and delineate the
differences between Au and Ag as electrode materials. Alignment of the bundles
between electrodes occurs at frequencies above 1 kHz. Control over the number
of trapped bundles is achieved by choosing an electrode material which
interacts strongly with the chemical functional groups of the carbon nanotubes,
with superior contacts being formed with Ag electrodes.Comment: 4 pages, RevTe
Cavity QED with optically transported atoms
Ultracold Rb atoms are delivered into a high-finesse optical
micro-cavity using a translating optical lattice trap and detected via the
cavity field. The atoms are loaded into an optical lattice from a magneto-optic
trap (MOT) and transported 1.5 cm into the cavity. Our cavity satisfies the
strong-coupling requirements for a single intracavity atom, thus permitting
real-time observation of single atoms transported into the cavity. This
transport scheme enables us to vary the number of intracavity atoms from 1 to
100 corresponding to a maximum atomic cooperativity parameter of 5400, the
highest value ever achieved in an atom--cavity system. When many atoms are
loaded into the cavity, optical bistability is directly measured in real-time
cavity transmission.Comment: 4 figures, 4 page
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