A5008057559- Advanced Frequency and Time Standards
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Fiber Laser Technologies
- Atomic and Subatomic Physics Research
- Quantum optics and atomic interactions
- Quantum Information and Cryptography
- Photonic and Optical Devices
- Spectroscopy and Laser Applications
- Mechanical and Optical Resonators
- Geophysics and Sensor Technology
- Solid State Laser Technologies
- Quantum Mechanics and Applications
- Advanced Measurement and Metrology Techniques
- Scientific Measurement and Uncertainty Evaluation
- Cardiovascular Syncope and Autonomic Disorders
- Laser Design and Applications
- Laser-Matter Interactions and Applications
- Nonlinear Dynamics and Pattern Formation
- Superconducting and THz Device Technology
- Pulsars and Gravitational Waves Research
- Physics of Superconductivity and Magnetism
- Advanced Optical Sensing Technologies
- Optical Systems and Laser Technology
- Magnetic properties of thin films
- Radioactive Decay and Measurement Techniques
Physikalisch-Technische Bundesanstalt
2015-2024
Max Planck Society
2001-2010
Max Planck Institute of Quantum Optics
2000-2010
Freie Universität Berlin
1999
Optical clocks show unprecedented accuracy, surpassing that of previously available clock systems by more than one order magnitude. Precise intercomparisons will enable a variety experiments, including tests fundamental quantum physics and cosmology applications in geodesy navigation. Well-established, satellite-based techniques for microwave dissemination are not adequate to compare optical clocks. Here, we present phase-stabilized distribution an frequency over 920 kilometers...
We report on two ultrastable lasers each stabilized to independent silicon Fabry-P\'erot cavities operated at 124 K. The fractional frequency instability of laser is completely determined by the fundamental thermal Brownian noise mirror coatings with a flicker floor $4 \times 10^{-17}$ for integration times between 0.8 s and few tens seconds. rigorously treat notorious divergencies encountered associated derive methods relate this observable practically relevant linewidths coherence times....
Abstract Leveraging the unrivalled performance of optical clocks as key tools for geo-science, astronomy and fundamental physics beyond standard model requires comparing frequency distant faithfully. Here, we report on comparison agreement two strontium at an uncertainty 5 × 10 −17 via a newly established phase-coherent link connecting Paris Braunschweig using 1,415 km telecom fibre. The remote is limited only by instability lattice themselves, with negligible contributions from transfer. A...
We present a laser system based on 48 cm long optical glass resonator. The large size requires sophisticated thermal control and optimized mounting design. A self-balancing was essential to reliably reach sensitivities acceleration of below Δν/ν<2×10(-10)/g in all directions. Furthermore, fiber noise cancellations from common reference point near the diode cavity mirror additional user points (Sr clock frequency comb) are implemented. Through comparison with other cavity-stabilized lasers...
Abstract Ultrastable lasers are essential tools in optical frequency metrology enabling unprecedented measurement precision that impacts on fields such as atomic timekeeping, tests of fundamental physics, and geodesy. To characterise an ultrastable laser it needs to be compared with a similar performance, but suitable system may not available locally. Here, we report comparison two geographically separated lasers, over the longest ever reported metrological fibre link network, measuring 2220...
The interference of two single photons impinging on a beam splitter is measured in time-resolved manner. Using long different frequencies emitted from an atom-cavity system, quantum beat with visibility close to 100% observed the correlation between photodetections at output ports splitter. time dependence amplitude reflects coherence properties photons. Most remarkably, simultaneous are never observed, so that temporal filter allows one obtain perfect two-photon coalescence even for nonperfect
We report on the first observation of stimulated Raman scattering from a Lambda-type three-level atom, where stimulation is realized by vacuum field high-finesse optical cavity. The scheme produces one intracavity photon means an adiabatic passage technique based counterintuitive interaction sequence between pump laser and cavity field. This leaves through less-reflecting mirror. emission rate shows characteristic dependence detuning, observed spectra have subnatural linewidth. results are...
We have measured the frequency of extremely narrow 1S-2S two-photon transition in atomic hydrogen using a remote cesium fountain clock with help 920 km stabilized optical fiber. With an improved detection method we obtain f(1S-2S)=2466 061 413 187 018 (11) Hz relative uncertainty 4.5×10(-15), confirming our previous measurement obtained local [C. G. Parthey et al., Phys. Rev. Lett. 107, 203001 (2011)]. Combining these results older measurements, constrain linear combinations Lorentz boost...
Active control and cancellation of residual amplitude modulation (RAM) in phase an optical carrier is one the key technologies for achieving ultimate stability a laser locked to ultrastable cavity. Furthermore, such techniques are versatile tools various frequency modulation-based spectroscopy applications. In this Letter we report simple robust approach actively stabilize RAM process. We employ waveguide-based electro-optic modulator (EOM) provide implement active servo with both DC...
Crystalline optical cavities are the foundation of today's stateof-the-art ultrastable lasers.Building on our previous silicon cavity effort, we now achieve fundamental thermal-noiselimited stability for a 6 cm long cooled to 4 K, reaching 6.5 × 10 -17 from 0.8 s 80 s.We also report first time, best knowledge, clear linear dependence frequency drift incident power.The lowest fractional -3 -19 ∕s is attained at transmitted power 40 nW, with an extrapolated approaching zero in absence...
We investigate the thermal expansion of low noise Fabry–Pérot cavities made (LTE) glass spacers and fused silica (FS) mirrors. The different mirror spacer deforms mirror. This deformation strongly contributes to cavity’s effective coefficient (CTE), decreasing zero crossing temperature by about 20 K compared an all-LTE cavity. Finite element simulations CTE measurements show that LTE rings optically contacted back surface FS mirrors allow tune over a range 30 K.
We report on a laser locked to silicon cavity operating continuously at 4 K with $1 \times 10^{-16}$ instability and median linewidth of 17 mHz 1542 nm. This is ten-fold improvement in short-term instability, $10^4$ linewidth, over previous sub-10 systems. Operating low temperatures reduces the thermal noise floor, thus advantageous toward reaching an $10^{-18}$, long-sought goal optical clock community. The performance this system demonstrates technical readiness for development next...
We search for transient variations of the fine structure constant using data from a European network fiber-linked optical atomic clocks. By searching coherent in recorded clock frequency comparisons across network, we significantly improve constraints on constant. For example, constrain variation alpha to <5*10^-17 transients duration 10^3 s. This analysis also presents possibility dark matter, mysterious substance hypothesised explain galaxy dynamics and other astrophysical phenomena that...
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....
Thermal noise of optical reference cavities sets a fundamental limit to the frequency instability ultrastable lasers. Using Levin's formulation fluctuation-dissipation theorem, we correct analytical estimate for spacer contribution given by Numata et al. [Phys. Rev. Lett.93, 250602 (2004)]. For detailed analysis, finite-element calculations thermal focusing on geometry, support structure, and usage different materials have been carried out. We find that increased dissipation close contact...
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...
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...
Cryogenic single-crystal optical cavities have the potential to provide highest dimensional stability. We investigated long-term performance of an ultra-stable laser system which is stabilized a silicon cavity operated at 124 K. Utilizing frequency comb, compared hydrogen maser that referenced primary caesium fountain standard and $^{87}\mathrm{Sr}$ lattice clock PTB. With fractional instabilities $\sigma_y(\tau)\leq2\times10^{-16}$ for averaging times $\tau=60\mathrm{~s}$ $1000\mathrm{~s}$...
We present a compact and robust transportable ultra-stable laser system with minimum fractional frequency instability of 1 × 10(-15) at integration times between 10 s. The was conceived as prototype subsystem microwave-optical local oscillator to be used on the satellite mission Space-Time Explorer QUantum Equivalence Principle Space Test (STE-QUEST) (http://sci.esa.int/ste-quest/). It therefore designed compact, sustain accelerations occurring during rocket launch, exhibit low vibration...
We report on a series of 42 measurements the transition frequency 429 THz (5s2) S01–(5s5p) P03 line in Sr87 taken over three years from 2017 to 2019. They were performed at Physikalisch-Technische Bundesanstalt (PTB) between laboratory strontium lattice clock and primary caesium fountain clocks CSF1 CSF2. The length each individual measurement run has been extended by use hydrogen maser as flywheel improve statistical uncertainty given Cs clocks. determine an averaged...