32 research outputs found
Nanofiber-based optical trapping of cold neutral atoms
We present experimental techniques and results related to the optimization
and characterization of our nanofiber-based atom trap [Vetsch et al., Phys.
Rev. Lett. 104, 203603 (2010)]. The atoms are confined in an optical lattice
which is created using a two-color evanescent field surrounding the optical
nanofiber. For this purpose, the polarization state of the trapping light
fields has to be properly adjusted. We demonstrate that this can be
accomplished by analyzing the light scattered by the nanofiber. Furthermore, we
show that loading the nanofiber trap from a magneto-optical trap leads to
sub-Doppler temperatures of the trapped atomic ensemble and yields a
sub-Poissonian distribution of the number of trapped atoms per trapping site
A Nanofiber-Based Optical Conveyor Belt for Cold Atoms
We demonstrate optical transport of cold cesium atoms over millimeter-scale
distances along an optical nanofiber. The atoms are trapped in a
one-dimensional optical lattice formed by a two-color evanescent field
surrounding the nanofiber, far red- and blue-detuned with respect to the atomic
transition. The blue-detuned field is a propagating nanofiber-guided mode while
the red-detuned field is a standing-wave mode which leads to the periodic axial
confinement of the atoms. Here, this standing wave is used for transporting the
atoms along the nanofiber by mutually detuning the two counter-propagating
fields which form the standing wave. The performance and limitations of the
nanofiber-based transport are evaluated and possible applications are
discussed
A single-atom heat engine
Heat engines convert thermal energy into mechanical work and generally involve a large number of particles. We report the experimental realization of a single-atom heat engine. An ion is confined in a linear Paul trap with tapered geometry and driven thermally by coupling it alternately to hot and cold reservoirs. The output power of the engine is used to drive a harmonic oscillation. From direct measurements of the ion dynamics, we were able to determine the thermodynamic cycles for various temperature differences of the reservoirs. We then used these cycles to evaluate the power P and efficiency η of the engine, obtaining values up to P = 3.4 × 10–22 joules per second and η = 0.28%, consistent with analytical estimations. Our results demonstrate that thermal machines can be reduced to the limit of single atoms