A5006709082- Advanced Frequency and Time Standards
- Cold Atom Physics and Bose-Einstein Condensates
- Atomic and Subatomic Physics Research
- Advanced Fiber Laser Technologies
- Quantum, superfluid, helium dynamics
- Quantum optics and atomic interactions
- Physics of Superconductivity and Magnetism
- Cardiovascular Syncope and Autonomic Disorders
- Photonic and Optical Devices
- Solid State Laser Technologies
- Optical properties and cooling technologies in crystalline materials
- Scientific Measurement and Uncertainty Evaluation
- Advanced Measurement and Metrology Techniques
- Pulsars and Gravitational Waves Research
- High-pressure geophysics and materials
- Superconducting and THz Device Technology
- Radioactive Decay and Measurement Techniques
- Paranormal Experiences and Beliefs
- Theoretical and Computational Physics
- Dark Matter and Cosmic Phenomena
- Artificial Intelligence in Games
- Particle accelerators and beam dynamics
- Quantum Information and Cryptography
- Quantum many-body systems
- Laser Design and Applications
University of Colorado Boulder
2016-2024
National Institute of Standards and Technology
2019-2024
Joint Institute for Laboratory Astrophysics
2016-2023
Physikalisch-Technische Bundesanstalt
2023
Heidelberg University
2014-2016
When an impurity is immersed in a Bose-Einstein condensate, impurity-boson interactions are expected to dress the into quasiparticle, Bose polaron. We superimpose ultracold atomic gas of $^{87}$Rb with much lower density fermionic $^{40}$K impurities. Through use Feshbach resonance and RF spectroscopy, we characterize energy, spectral width lifetime resultant polaron on both attractive repulsive branches strongly interacting regime. The branch narrow compared its binding even as two-body...
We conduct frequency comparisons between a state-of-the-art strontium optical lattice clock, cryogenic crystalline silicon cavity, and hydrogen maser to set new bounds on the coupling of ultralight dark matter Standard Model particles fields in mass range $10^{-16}$ $-$ $10^{-21}$ eV. The key advantage this two-part ratio comparison is differential sensitivities time variation both fine-structure constant electron mass, achieving substantially improved limit moduli matter, particularly at...
The condensation of fermion pairs lies at the heart superfluidity. However, for strongly correlated systems with reduced dimensionality mechanisms pairing and are still not fully understood. In our experiment we use ultracold atoms as a generic model system to study phase transition from normal condensed in interacting quasi-two-dimensional Fermi gas. Using novel method, obtain situ pair momentum distribution observe emergence low-momentum condensate low temperatures. By tuning temperature...
We experimentally investigate the first-order correlation function of a trapped Fermi gas in two-dimensional BEC-BCS crossover. observe transition to low-temperature superfluid phase with algebraically decaying correlations. show that spatial coherence entire system can be characterized by single temperature-dependent exponent. find exponent at constant over wide range interaction strengths across This suggests transitions both bosonic regime and strongly interacting crossover are...
We report the experimental measurement of equation state a two-dimensional Fermi gas with attractive s-wave interactions throughout crossover from weakly coupled to Bose tightly bound dimers as interaction strength is varied. demonstrate that lead renormalization density by several orders magnitude. compare our data near ground and at finite temperature predictions for both fermions bosons Quantum Monte Carlo simulations Luttinger-Ward theory. Our results serve input investigations...
State-of-the-art optical oscillators employing cryogenic reference cavities are limited in performance by the Brownian thermal noise associated with mechanical dissipation of mirror coatings. Recently, crystalline Al 1− x Ga As/GaAs coatings have emerged as a promising candidate for improved coating noise. We present measurements frequency two fully 0.92 0.08 report on birefringent anticorrelated fluctuations between polarization modes and identify variables that affect its magnitude....
We report on the first timescale based entirely optical technology. Existing timescales, including those incorporating frequency standards, rely exclusively microwave local oscillators owing to lack of an oscillator with required predictability and stability for reliable steering. combine a cryogenic silicon cavity exhibiting improved long-term accurate ^{87}Sr lattice clock form that outperforms them all. Our accumulates estimated time error only 48±94 ps over 34 days operation. analysis...
We report on an improved systematic evaluation of the JILA SrI optical lattice clock, achieving a nearly identical uncertainty compared to previous strontium record set by SrII clock at . This improves upon in 2013, and we achieve more than twenty-fold reduction A seven-fold improvement stability, reaching for averaging time seconds, allows average its under 10 min. improve budget several important ways. includes novel scheme taming blackbody radiation-induced frequency shifts through active...
Engineering a Hamiltonian system with tunable interactions provides opportunities to optimize performance for quantum sensing and explore emerging phenomena of many-body systems. An optical lattice clock based on partially delocalized Wannier-Stark states in gravity-tilted shallow supports superior coherence adjustable via spin-orbit coupling, thus presenting powerful spin model realization. The relative strength the on-site off-site can be tuned achieve zero density shift at "magic" depth....
Thermodynamically induced length fluctuations of high-reflectivity mirror coatings put a fundamental limit on sensitivity and stability precision optical interferometers like gravitational-wave detectors ultrastable lasers. The main contribution—Brownian thermal noise—is related to the mechanical loss coating material. Al0.92Ga0.08As/GaAs crystalline are expected reduce this limit. first measurements cryogenic silicon cavities revealed existence additional noise contributions exceeding...
We demonstrate and characterize an experimental technique to directly image the momentum distribution of a strongly interacting two-dimensional quantum gas with high resolution. apply principles Fourier optics investigate three main operations on expanding gas: focusing, collimation magnification. focus in radial plane using harmonic confining potential thus gain access distribution. pulse different stop rapid axial expansion which allows us Additionally, we propose method magnify mapped...
In this Perspective we summarize the status of technological development for large-area and low-noise substrate-transferred GaAs/AlGaAs (AlGaAs) crystalline coatings interferometric gravitational-wave (GW) detectors. These topics were originally presented in a workshop{\dag} bringing together members GW community from laser interferometer observatory (LIGO), Virgo, KAGRA collaborations, along with scientists precision optical metrology community, industry partners extensive expertise...
Atomic clocks occupy a unique position in measurement science, exhibiting higher accuracy than any other standard and underpinning six out of seven base units the SI system. By exploiting resonance frequencies, optical atomic now achieve greater stability lower frequency uncertainty existing primary standards. Here, we report ratios $^{27}$Al$^+$, $^{171}$Yb $^{87}$Sr Boulder, Colorado, measured across an network spanned by both fiber free-space links. These have been evaluated with...
Mechanical loss of dielectric mirror coatings sets fundamental limits for both gravitational wave detectors and cavity-stabilized optical local oscillators atomic clocks. Two approaches are used to determine the mechanical loss: ringdown measurements coating quality factor direct measurement thermal noise. Here we report a systematic study noise from room temperature 4 K by operating reference cavities at these temperatures. The directly measured is extract corresponding SiO$_2$/Ta$_2$O$_5$...
The Pound–Drever–Hall (PDH) cavity-locking scheme has found prevalent uses in precision optical interferometry and laser frequency stabilization. A form of modulation spectroscopy, PDH enjoys superior signal-to-noise recovery, large acquisition dynamic range, wide servo bandwidth, robust rejection spurious effects. However, residual amplitude at the signal frequency, while significantly suppressed, still presents an important concern for further advancing state-of-the-art performances. Here...
We have investigated crystalline AlGaAs/GaAs optical coatings with three ultra-stable cavities operating at 4 K, 16 124 K and 297 K. The response of the resonance frequencies to variations in power indicates effects beyond photo-thermo-optic effect observed dielectric coatings. These are strongly dependent on intensity intracavity light 1.5~\textmu m. When rear side mirrors is illuminated external light, we observe a prominent photo-modified birefringence for photon energies above GaAs...