208 research outputs found
Direct frequency comb laser cooling and trapping
Continuous wave (CW) lasers are the enabling technology for producing
ultracold atoms and molecules through laser cooling and trapping. The resulting
pristine samples of slow moving particles are the de facto starting point for
both fundamental and applied science when a highly-controlled quantum system is
required. Laser cooled atoms have recently led to major advances in quantum
information, the search to understand dark energy, quantum chemistry, and
quantum sensors. However, CW laser technology currently limits laser cooling
and trapping to special types of elements that do not include highly abundant
and chemically relevant atoms such as hydrogen, carbon, oxygen, and nitrogen.
Here, we demonstrate that Doppler cooling and trapping by optical frequency
combs may provide a route to trapped, ultracold atoms whose spectra are not
amenable to CW lasers. We laser cool a gas of atoms by driving a two-photon
transition with an optical frequency comb, an efficient process to which every
comb tooth coherently contributes. We extend this technique to create a
magneto-optical trap (MOT), an electromagnetic beaker for accumulating the
laser-cooled atoms for further study. Our results suggest that the efficient
frequency conversion offered by optical frequency combs could provide a key
ingredient for producing trapped, ultracold samples of nature's most abundant
building blocks, as well as antihydrogen. As such, the techniques demonstrated
here may enable advances in fields as disparate as molecular biology and the
search for physics beyond the standard model.Comment: 10 pages, 5 figure
Nanoscale electrical conductivity imaging using a nitrogen-vacancy center in diamond
The electrical conductivity of a material can feature subtle, nontrivial, and
spatially-varying signatures with critical insight into the material's
underlying physics. Here we demonstrate a conductivity imaging technique based
on the atom-sized nitrogen-vacancy (NV) defect in diamond that offers local,
quantitative, and noninvasive conductivity imaging with nanoscale spatial
resolution. We monitor the spin relaxation rate of a single NV center in a
scanning probe geometry to quantitatively image the magnetic fluctuations
produced by thermal electron motion in nanopatterned metallic conductors. We
achieve 40-nm scale spatial resolution of the conductivity and realize a
25-fold increase in imaging speed by implementing spin-to-charge conversion
readout of a shallow NV center. NV-based conductivity imaging can probe
condensed-matter systems in a new regime, and as a model example, we project
readily achievable imaging of nanoscale phase separation in complex oxides.Comment: Supplementary information at en
Phonon lasing from optical frequency comb illumination of a trapped ion
An atomic transition can be addressed by a single tooth of an optical
frequency comb if the excited state lifetime () is significantly longer
than the pulse repetition period (). In the crossover regime
between fully-resolved and unresolved comb teeth (), we observe Doppler cooling of a pre-cooled trapped atomic ion
by a single tooth of a frequency-doubled optical frequency comb. We find that
for initially hot ions, a multi-tooth effect gives rise to lasing of the ion's
harmonic motion in the trap, verified by acoustic injection locking. The gain
saturation of this phonon laser action leads to a comb of steady-state
oscillation amplitudes, allowing hot ions to be loaded directly into the trap
and laser cooled to crystallization despite the presence of hundreds of
blue-detuned teeth.Comment: 5 pages, 4 figure
Noise thermometry and electron thermometry of a sample-on-cantilever system below 1 Kelvin
We have used two types of thermometry to study thermal fluctuations in a
microcantilever-based system below 1 K. We measured the temperature of a
cantilever's macroscopic degree-of-freedom (via the Brownian motion of its
lowest flexural mode) and its microscopic degrees-of-freedom (via the electron
temperature of a metal sample mounted on the cantilever). We also measured both
temperatures' response to a localized heat source. We find it possible to
maintain thermal equilibrium between these two temperatures and a refrigerator
down to at least 300 mK. These results are promising for ongoing experiments to
probe quantum effects using micromechanical devices
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