292 research outputs found
A Cold-Strontium Laser in the Superradiant Crossover Regime
Recent proposals suggest that lasers based on narrow dipole-forbidden
transitions in cold alkaline earth atoms could achieve linewidths that are
orders of magnitude smaller than linewidths of any existing lasers. Here, we
demonstrate a laser based on the 7.5 kHz linewidth dipole forbidden P
to S transition in laser-cooled and tightly confined Sr. We can
operate this laser in the bad-cavity regime, where coherence is primarily
stored in the atoms, or continuously tune to the more conventional good-cavity
regime, where coherence is primarily stored in the light field. We show that
the cold-atom gain medium can be repumped to achieve quasi steady-state lasing,
and demonstrate up to an order of magnitude suppression in the sensitivity of
laser frequency to changes in cavity length, the primary limitation for the
most frequency stable lasers today.Comment: 5 pages, 4 figure
How does a bicycle work? A new instrument to assess mechanical reasoning in school aged children
This study demonstrated that a brief interview can reveal the mechanical reasoning that could not be assessed via the Bicycle Drawing Test. This study, conducted on 190 children (6 to 11 years old), shows that mechanical reasoning improves with age. It shows correlations with spatial reasoning and motor control, and with visual reasonin
- …