8 research outputs found
An ultrastable silicon cavity in a continuously operating closed-cycle cryostat at 4 K
We report on a laser locked to a silicon cavity operating continuously at 4 K
with instability and a median linewidth of 17 mHz at 1542
nm. This is a ten-fold improvement in short-term instability, and a
improvement in linewidth, over previous sub-10 K systems. Operating at low
temperatures reduces the thermal noise floor, and thus is advantageous toward
reaching an instability of , a long-sought goal of the optical clock
community. The performance of this system demonstrates the technical readiness
for the development of the next generation of ultrastable lasers that operate
with ultranarrow linewidth and long-term stability without user intervention.Comment: 5 pages, 4 figure
A Fermi-degenerate three-dimensional optical lattice clock
Strontium optical lattice clocks have the potential to simultaneously
interrogate millions of atoms with a high spectroscopic quality factor of . Previously, atomic interactions have forced a compromise
between clock stability, which benefits from a large atom number, and accuracy,
which suffers from density-dependent frequency shifts. Here, we demonstrate a
scalable solution which takes advantage of the high, correlated density of a
degenerate Fermi gas in a three-dimensional optical lattice to guard against
on-site interaction shifts. We show that contact interactions are resolved so
that their contribution to clock shifts is orders of magnitude lower than in
previous experiments. A synchronous clock comparison between two regions of the
3D lattice yields a measurement precision in 1 hour of
averaging time.Comment: 19 pages, 4 figures; Supplementary Material
Optical clock intercomparison with precision in one hour
Improvements in atom-light coherence are foundational to progress in quantum
information science, quantum optics, and precision metrology. Optical atomic
clocks require local oscillators with exceptional optical coherence due to the
challenge of performing spectroscopy on their ultra-narrow linewidth clock
transitions. Advances in laser stabilization have thus enabled rapid progress
in clock precision. A new class of ultrastable lasers based on cryogenic
silicon reference cavities has recently demonstrated the longest optical
coherence times to date. In this work we utilize such a local oscillator, along
with a state-of-the-art frequency comb for coherence transfer, with two Sr
optical lattice clocks to achieve an unprecedented level of clock stability.
Through an anti-synchronous comparison, the fractional instability of both
clocks is assessed to be for an averaging time
in seconds. Synchronous interrogation reveals a quantum projection noise
dominated instability of , resulting in a
precision of after a single hour of averaging. The
ability to measure sub- level frequency shifts in such short
timescales will impact a wide range of applications for clocks in quantum
sensing and fundamental physics. For example, this precision allows one to
resolve the gravitational red shift from a 1 cm elevation change in only 20
minutes
Optical Atomic Clock Comparison through Turbulent Air
We use frequency comb-based optical two-way time-frequency transfer (O-TWTFT)
to measure the optical frequency ratio of state-of-the-art ytterbium and
strontium optical atomic clocks separated by a 1.5 km open-air link. Our
free-space measurement is compared to a simultaneous measurement acquired via a
noise-cancelled fiber link. Despite non-stationary, ps-level time-of-flight
variations in the free-space link, ratio measurements obtained from the two
links, averaged over 30.5 hours across six days, agree to ,
showing that O-TWTFT can support free-space atomic clock comparisons below the
level