A5056620934- Advanced Fiber Laser Technologies
- Dark Matter and Cosmic Phenomena
- Advanced Frequency and Time Standards
- Atomic and Subatomic Physics Research
- Particle physics theoretical and experimental studies
- Cosmology and Gravitation Theories
- Cold Atom Physics and Bose-Einstein Condensates
- Spectroscopy and Laser Applications
- Photonic and Optical Devices
- Astrophysics and Cosmic Phenomena
- Mechanical and Optical Resonators
- Quantum optics and atomic interactions
- Advanced Measurement and Metrology Techniques
- Advanced Photonic Communication Systems
- Sensor Technology and Measurement Systems
- Experimental and Theoretical Physics Studies
- Particle Detector Development and Performance
- Laser Design and Applications
- Non-Invasive Vital Sign Monitoring
- Advanced Electrical Measurement Techniques
- Semiconductor Lasers and Optical Devices
Peking University
2021-2024
Lawrence Livermore National Laboratory
2006
Massachusetts Institute of Technology
2001-2004
The axion is a hypothetical elementary particle and cold dark matter candidate. In this rf cavity experiment, halo axions entering resonant immersed in static magnetic field convert into microwave photons, with the resulting photons detected by low-noise receiver. ADMX Collaboration presents new limits on axion-to-photon coupling local mass density from search range $1.9--2.3\ensuremath{\mu}\mathrm{eV},$ broadening to $1.9--3.3\ensuremath{\mu}\mathrm{eV}.$ addition, we report first results...
We have performed a high resolution search for galactic halo axions in cold flows using microwave cavity detector. The analysis procedure and other details of this are described. No axion signal was found the mass range $1.98--2.17\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$. place upper limits on density local discrete based result.
Abstract Ultralight bosons such as axion-like particles are viable candidates for dark matter. They can form stable, macroscopic field configurations in the of topological defects that could concentrate matter density into many distinct, compact spatial regions small compared with Galaxy but much larger than Earth. Here we report results search transient signals from domain walls by using global network optical magnetometers exotic (GNOME) physics searches. We data, consisting correlated...
Most of the mass Milky Way galaxy is contributed by its halo, presumably in form non-interacting cold dark matter.The axion a compelling matter candidate.We report results from search which probes local galactic halo density using Sikivie RF cavity technique.Candidates over frequency range 550 ≤ f 810 MHz (2.3 µeV m 3.4 µeV) were investigated.The absence signal suggests that KSVZ axions contribute no more than 0.45 GeV/cm 3 to this range.
Time and frequency transfer plays an important role in the fields of navigation positioning, remote sensing, fundamental physics. The performance long-haul is ultimately limited by accumulated phase amplitude noise fiber propagation. In this work we overcome these limitations demonstrate a system over 3000 km indoor spooled fibers via repetition-frequency-locked combs, which benefit from extremely high signal-to-noise ratio. With help digital discrimination compensation method active power...
The large-scale clock network is the key ingredient to obtain high precision in many scenarios, from fundamental research cutting-edge applications. advantage of time synchronization among microwave clocks their cost, size, and accessibility. Here, we demonstrate a femtosecond-level through commercial link 205.86 km via dual-comb-enhanced optical two-way transfer, which achieves 6.23-fs residual deviation between synchronized timescales at 1 s an instability below 6×10 −18 10,000 s. Further,...
Abstract Numerous observations suggest that there exist undiscovered beyond‐the‐standard‐model particles and fields. Because of their unknown nature, these exotic fields could interact with standard model in many different ways assume a variety possible configurations. Here, an overview the global network optical magnetometers for physics searches (GNOME), ongoing experimental program designed to test wide range scenarios, is presented. The GNOME experiment utilizes worldwide shielded atomic...
High-precision time-interval measurement is a fundamental technique in many advanced applications, including time and distance metrology, particle physics, ultra-precision machining. However, of these applications are confined by the imprecise electrical signals, restricting performance ultimate system to few picoseconds, which limits ultra-high-precision applications. Here, we demonstrate an optical means signals that can successfully achieve femtosecond (fs)-level precision. The setup...
The large-scale clock network is the key ingredient to obtain high precision in many scenarios, from fundamental research cutting-edge applications. advantage of time synchronization among microwave clocks their cost, size, and accessibility. Here, we demonstrate a femtosecond-level through commercial link 205.86 km via dual-comb-enhanced optical two-way transfer, which achieves 6.23-fs residual deviation between synchronized timescales at 1 s an instability below 6E-18 10,000 s. Further,...
The axion is a hypothetical elementary particle and cold dark matter candidate. It could dominate the potential wells of most astrophysical objects. Axions spontaneously decay into nearly monochromatic microwave photons. We present results from radio telescope search for these photons mass ma = 298-363 μeV in Local Group dwarf galaxies. report limit on axion-to-two-photon coupling constant gaγγ > 1.0 × 10-9 GeV-1.
Fiber-delay measurement is one of the key fundamental technologies in numerous fields. Here, we propose and experimentally demonstrate a high-precision concise optical time delay system based on technique linear sampling, reaching precision better than 100 fs under averaging. The use only two frequency combs without locking carrier-envelope-offset greatly simplifies structure time-delay system. We also investigate current limitations timing jitter noises sources are mainly non-common mode...
Abstract Results are reported from the first full-scale search for transient signals exotic fields of astrophysical origin using data a newly constructed Earth-scale detector: Global Network Optical Magnetometers Exotic physics searches (GNOME). Data collected by GNOME consist correlated measurements optical atomic magnetometers located in laboratories all over world. searched patterns propagating through network consistent with composed ultralight bosons such as axion-like particles (ALPs)....
Abstract This paper proposes a method to achieve long-term locking of the repetition frequency optical comb under severe temperature fluctuations by cooperatively adjusting cavity length resonator using piezoelectric ceramic, control module, and delay line module. enhances practicability usability at low cost.
To meet the requirements of time-frequency networks and enable frequency downloadability for nodes along link, we demonstrated extraction stable signals at using a mode-locked laser under condition 100 km laboratory fiber. The node consists simple structure that utilizes widely used optoelectronic devices enables plug-and-play applications. In addition, can recover with multiple frequencies, which are useful scenarios require different frequencies. Here, experimentally short-term instability...
SummaryMixer is usually used as the phase discriminator in a frequency transfer system, of which characteristics are directly related to stability transfered signal. This experiment verifies system amplitude and noise conversion mixers. The output mixer minimum when two inputed signals nearly orthogonal, called Sweet Point. Compared with other cases, fluctuations at Point can be reduced by an order magnitude measured instability improved.
The axion is a hypothetical elementary particle and cold dark matter candidate. In this RF cavity experiment, halo axions entering resonant immersed in static magnetic field convert into microwave photons, with the resulting photons detected by low-noise receiver. ADMX Collaboration presents new limits on axion-to-photon coupling local mass density from search range 1.9-2.3 microeV, broadening to 1.9-3.3 microeV. addition, we report first results an improved analysis technique.
Mixer is of crucial importance in evaluating the precision frequency transfer. We present preliminary results on optimization practical mixer's LO and RF input power parameters when performing downconversion. A fractional instability better than 2E-13@1 s via 100 km fiber link with MHz repetition optical comb measured under optimized parameters.
We experimentally demonstrate a frequency transfer over 1000 km of fiber by exploiting the optical comb. Through feedback phase shifter, active noise cancellation is achieved. The fractional instability 2.4×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−15</sup> at 1 s and 1.1×10 xmlns:xlink="http://www.w3.org/1999/xlink">−18</sup> 10000 are measured respectively. results support ultrastable applications via long-haul links.
As an essential active device, electrical preamplifier has significant effect on frequency stability, which is extremely demanded by a transfer system. In this work, we build optical-comb based system and investigate the influences of noise in determining ultimate instability The experimental results show that increasing amplifier gain no contribution to improvement when higher than measuring 2E-14@1 s achieved with varying from 1 100. Moreover, if below 1E-15@1 be transferred, should...