53 research outputs found
Seconds-scale coherence in a tweezer-array optical clock
Optical clocks based on atoms and ions achieve exceptional precision and
accuracy, with applications to relativistic geodesy, tests of relativity, and
searches for dark matter. Achieving such performance requires balancing
competing desirable features, including a high particle number, isolation of
atoms from collisions, insensitivity to motional effects, and high duty-cycle
operation. Here we demonstrate a new platform based on arrays of ultracold
strontium atoms confined within optical tweezers that realizes a novel
combination of these features by providing a scalable platform for isolated
atoms that can be interrogated multiple times. With this tweezer-array clock,
we achieve greater than 3 second coherence times and record duty cycles up to
96%, as well as stability commensurate with leading platforms. By using optical
tweezer arrays --- a proven platform for the controlled creation of
entanglement through microscopic control --- this work further promises a new
path toward combining entanglement enhanced sensitivities with the most precise
optical clock transitions
Crystalline optical cavity at 4 K with thermal noise limited instability and ultralow drift
Crystalline optical cavities are the foundation of today's state-of-the-art
ultrastable lasers. Building on our previous silicon cavity effort, we now
achieve the fundamental thermal noise-limited stability for a 6 cm long silicon
cavity cooled to 4 Kelvin, reaching from 0.8 to 80 seconds.
We also report for the first time a clear linear dependence of the cavity
frequency drift on the incident optical power. The lowest fractional frequency
drift of /s is attained at a transmitted power of 40 nW, with
an extrapolated drift approaching zero in the absence of optical power. These
demonstrations provide a promising direction to reach a new performance domain
for stable lasers, with stability better than and fractional
linear drift below /s
Structural thermal noise in gram-scale mirror oscillators
The thermal noise associated with mechanical dissipation is a ubiquitous limitation to the sensitivity of precision experiments ranging from frequency stabilization to gravitational wave interferometry. We report on the thermal noise limits to the performance of 1 gm mirror oscillators that are part of a cavity optomechanics experiment to observe quantum radiation pressure noise. Thermal noise limits the observed cavity displacement spectrum from 80 Hz to 5 kHz. We present a calculation of the thermal noise, based on finite element analysis of the dissipation due to structural damping, and find it to be in excellent agreement with the experimental result. We conclude with the predicted thermal noise for an improved oscillator design, which should be capable of revealing the noise that arises from quantum backaction in this system.National Science Foundation (U.S.) (Grant PHY-1068772
Crystalline optical cavity at 4 K with thermal-noise-limited instability and ultralow drift
Crystalline optical cavities are the foundation of today’s state-of-the-art ultrastable lasers. Building on our previous silicon cavity effort, we now achieve the fundamental thermal-noise-limited stability for a 6 cm long silicon cavity cooled to 4 K, reaching 6.5×10−17 from 0.8 s to 80 s. We also report for the first time, to the best of our knowledge, a clear linear dependence of the cavity frequency drift on incident optical power. The lowest fractional frequency drift of −3×10−19/s is attained at a transmitted power of 40 nW, with an extrapolated drift approaching zero in the absence of optical power. These demonstrations provide a promising direction to reach a new performance domain for stable lasers, with stability better than 1×10−17 and fractional linear drift below 1×10−19/s
Precision Metrology Meets Cosmology: Improved Constraints on Ultralight Dark Matter from Atom-Cavity Frequency Comparisons
We conduct frequency comparisons between a state-of-the-art strontium optical
lattice clock, a cryogenic crystalline silicon cavity, and a hydrogen maser to
set new bounds on the coupling of ultralight dark matter to Standard Model
particles and fields in the mass range of eV. The key
advantage of this two-part ratio comparison is the differential sensitivities
to time variation of both the fine-structure constant and the electron mass,
achieving a substantially improved limit on the moduli of ultralight dark
matter, particularly at higher masses than typical atomic spectroscopic
results. Furthermore, we demonstrate an extension of the search range to even
higher masses by use of dynamical decoupling techniques. These results
highlight the importance of using the best performing atomic clocks for
fundamental physics applications as all-optical timescales are increasingly
integrated with, and will eventually supplant, existing microwave timescales.Comment: 11 pages, 10 figure
A tweezer clock with half-minute atomic coherence at optical frequencies and high relative stability
The preparation of large, low-entropy, highly coherent ensembles of identical
quantum systems is foundational for many studies in quantum metrology,
simulation, and information. Here, we realize these features by leveraging the
favorable properties of tweezer-trapped alkaline-earth atoms while introducing
a new, hybrid approach to tailoring optical potentials that balances
scalability, high-fidelity state preparation, site-resolved readout, and
preservation of atomic coherence. With this approach, we achieve trapping and
optical clock excited-state lifetimes exceeding seconds in ensembles of
approximately atoms. This leads to half-minute-scale atomic coherence
on an optical clock transition, corresponding to quality factors well in excess
of . These coherence times and atom numbers reduce the effect of
quantum projection noise to a level that is on par with leading atomic systems,
yielding a relative fractional frequency stability of
for synchronous clock comparisons
between sub-ensembles within the tweezer array. When further combined with the
microscopic control and readout available in this system, these results pave
the way towards long-lived engineered entanglement on an optical clock
transition in tailored atom arrays.Comment: 11 pages, 5 figures (main text); 17 pages, 7 figures (supplemental
materials
Excess noise and photo-induced effects in highly reflective crystalline mirror coatings
Thermodynamically induced length fluctuations of high-reflectivity mirror
coatings put a fundamental limit on sensitivity and stability of precision
optical interferometers like gravitational wave detectors and ultra-stable
lasers. The main contribution - Brownian thermal noise - is related to the
mechanical loss of the coating material. Owing to their low mechanical losses,
Al\textsubscript{0.92}Ga\textsubscript{0.08}As/GaAs crystalline mirror coatings
are expected to reduce this limit. At room temperature they have demonstrated
lower Brownian thermal noise than with conventional amorphous coatings.
%However, no detailed study on the noise constituents from these coatings in
optical interferometers has been conducted. We present a detailed study on the
spatial and temporal noise properties of such coatings by using them in two
independent cryogenic silicon optical Fabry-Perot resonators operated at 4 K,
16 K and 124 K. We confirm the expected low Brownian thermal noise, but also
discover two new noise sources that exceed the Brownian noise: birefringent
noise that can be canceled via polarization averaging and global excess noise
(10 dB above Brownian noise). These new noise contributions are a barrier to
improving ultra-stable lasers and the related performance of atomic clocks, and
potentially limit the sensitivity of third-generation gravitational wave
detectors. Hence, they must be considered carefully in precision interferometry
experiments using similar coatings based on semiconductor materials
First all-sky search for continuous gravitational waves from unknown sources in binary systems
We present the first results of an all-sky search for continuous gravitational waves from unknown spinning neutron stars in binary systems using LIGO and Virgo data. Using a specially developed analysis program, the TwoSpect algorithm, the search was carried out on data from the sixth LIGO science run and the second and third Virgo science runs. The search covers a range of frequencies from 20 Hz to 520 Hz, a range of orbital periods from 2 to ∼2,254  h and a frequency- and period-dependent range of frequency modulation depths from 0.277 to 100 mHz. This corresponds to a range of projected semimajor axes of the orbit from ∼0.6 × 10[superscript −3]  ls to ∼6,500  ls assuming the orbit of the binary is circular. While no plausible candidate gravitational wave events survive the pipeline, upper limits are set on the analyzed data. The most sensitive 95% confidence upper limit obtained on gravitational wave strain is 2.3 × 10[superscript −24] at 217 Hz, assuming the source waves are circularly polarized. Although this search has been optimized for circular binary orbits, the upper limits obtained remain valid for orbital eccentricities as large as 0.9. In addition, upper limits are placed on continuous gravitational wave emission from the low-mass x-ray binary Scorpius X-1 between 20 Hz and 57.25 Hz.National Science Foundation (U.S.)United States. National Aeronautics and Space AdministrationCarnegie TrustDavid & Lucile Packard FoundationResearch CorporationAlfred P. Sloan Foundatio
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