A5047732556- Advanced Frequency and Time Standards
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Fiber Laser Technologies
- Geodetic Measurements and Engineering Structures
- Advanced Measurement and Metrology Techniques
- Scientific Measurement and Uncertainty Evaluation
- Geophysics and Sensor Technology
- Laser Design and Applications
- Atomic and Subatomic Physics Research
- Semiconductor Lasers and Optical Devices
- Relativity and Gravitational Theory
- History and Developments in Astronomy
- Pulsars and Gravitational Waves Research
- Optical properties and cooling technologies in crystalline materials
- Solid State Laser Technologies
Physikalisch-Technische Bundesanstalt
2018-2024
Heinrich Heine University Düsseldorf
2018
University of Birmingham
2018
Optical lattice clocks with uncertainty and instability in the $10^{-17}$-range below have so far been demonstrated exclusively using fermions. Here, we demonstrate a bosonic optical clock $3\times 10^{-18}$ $2.0\times 10^{-17}$ accuracy, both values improving on previous work by factor 30. This was enabled probing transition an ultra-long interrogation time of 4 s, long coherence provided cryogenic silicon resonator, careful stabilization relevant operating parameters, at low atom density....
We present a transportable ultra-stable clock laser system based on Fabry-Perot cavity with crystalline Al0.92Ga0.08As/GaAs mirror coatings, fused silica (FS) substrates, and 20 cm-long ultra-low expansion (ULE) glass spacer predicted thermal noise floor of mod σy = 7 × 10-17 in modified Allan deviation at one second averaging time. The has cylindrical shape is mounted 10 points. Its measured sensitivity the fractional frequency to acceleration for three Cartesian directions are 2(1) 10-12...
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 have measured the geopotential difference between two locations separated by 457 km comparison of optical lattice clocks via an interferometric fiber link, utilizing gravitational redshift clock transition frequency. The <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><a:msup><a:mi/><a:mn>87</a:mn></a:msup><a:mi>Sr</a:mi></a:math> been compared side-by-side before and after one was moved to remote location. chronometrically <d:math...
Optical resonators are used for the realisation of ultra-stable frequency lasers. The use high reflectivity multi-band coatings allows locking several lasers different wavelengths to a single cavity. While noise processes wavelength cavities well known, correlation caused by multi-stack has as yet not been analysed experimentally. In our work, we stabilise 729 nm and 1069 laser one mirror pair determine residual-amplitude modulation (RAM) photo-thermal (PTN). We find correlations in PTN...
We present an interrogation laser system for a transportable strontium lattice clock operating at 698 nm, which is based on ultra-low-expansion glass reference cavity. Transportability achieved by implementing rigid, compact, and vibration insensitive mounting of the 12 cm-long cavity, sustaining shocks up to 50 g. The cavity mounted optimized support points that independently constrain all degrees freedom. This concept especially beneficial cavities with ratio length $L$ over diameter $D$...
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...
Frequency doublers are widely used in high-resolution spectroscopy to shift the operation wavelength of a laser more easily accessible or otherwise preferable spectral region. We investigate use periodically-poled lithium niobate (PPLN) waveguide frequency doubler an optical clock. focus on phase evolution between fundamental (1396 nm) and frequency-doubled (698 light its effect clock performance. find that excess noise under steady-state is at least two orders magnitude lower than today's...
SummaryWe discovered and characterized a novel birefringent noise in Al<inf>0.92</inf>Ga<inf>0.08</inf>As/GaAs crystalline mirror coatings at cryogenic temperature. We also determined the upper limit of coating Brownian reliable way. Our results indicate that excess related to semiconductor could be an obstacle reaching low thermal floor these coatings. investigations on provide important design considerations for precision interferometry
Optical clocks require an ultra-stable laser to probe and precisely measure the frequency of narrow-linewidth clock transition. We introduce a portable ultraviolet (UV) system for use in aluminum quantum logic clock, demonstrating fractional instability approximately mod σ y = 2 × 10 −16 . The is based on cavity with crystalline AlGaAs/GaAs mirror coatings, quadrupling employing two single-pass second-harmonic generation (SHG) stages. Its acceleration sensitivity, measured all three axes,...
We have measured the geopotential difference between two locations separated by 457 km comparison of optical lattice clocks via an interferometric fiber link, utilizing gravitational redshift clock transition frequency. The $^{87}$Sr been compared side-by-side before and after one was moved to remote location. chronometrically $3918.1(2.4)\,\mathrm{m^2 \, s^{-2}}$ agrees with independent geodetic determination $3915.88(0.30)\,\mathrm{m^2 s^{-2}}$. uncertainty chronometric is equivalent...
Thermodynamically induced length fluctuations of high-reflectivity mirror coatings put a fundamental limit on sensitivity and stability precision optical interferometers like gravitational wave detectors ultra-stable lasers. The main contribution - Brownian thermal noise is related to the mechanical loss coating material. Owing their low losses, Al\textsubscript{0.92}Ga\textsubscript{0.08}As/GaAs crystalline are expected reduce this limit. At room temperature they have demonstrated lower...
SummaryWe present a technique to stabilize laser frequency an average of different cavity modes via Pound-Drever-Hall (PDH) scheme. This was applied eliminate the instability arising from fluctuation birefringence in Al<inf>0.92</inf>Ga<inf>0.08</inf>As/GaAs crystalline mirror coatings by locking orthogonally polarized modes.
Ultra-stable laser systems are needed for precision measurements, e.g. with optical clocks, where the performance directly depends on lasers' fractional frequency instability. This instability is fundamentally limited by thermal noise in systems' ultra-stable resonators. To reach floor, technical of system must be reduced below limit. includes, resulting from power fluctuations, residual amplitude modulation PDH servo or seismic acting cavity.
Optical resonators are used for the realisation of ultra-stable frequency lasers. The use high reflectivity multi-band coatings allows locking several lasers different wavelengths to a single cavity. While noise processes wavelength cavities well known, correlation caused by multi-stack has as yet not been analysed experimentally. In our work, we stabilise $729\,$nm and $1069\,$nm laser one mirror pair determine residual-amplitude modulation (RAM) photo-thermal (PTN). We find correlations in...
We present a transportable ultra-stable clock laser system based on Fabry-Pérot cavity with crystalline Al$_{0.92}$Ga$_{0.08}$As/GaAs mirror coatings, fused silica (FS) substrates and 20~cm-long ultra-low expansion (ULE\textsuperscript{\textregistered}) glass spacer predicted thermal noise floor of $\mathrm{mod}\,σ_\mathrm{y} = 7 \times 10^{-17}$ in modified Allan deviation at one second averaging time. The has cylindrical shape is mounted ten points. Its measured sensitivity the fractional...