强激光与粒子束
2023, 35(4): 041003
Author Affiliations
Abstract
1 Key Laboratory of Quantum Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201 800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
The environmental perturbation on atoms is a key factor restricting the performance of atomic frequency standards, especially in the long-term scale. In this Letter, we perform a real-time noise distinguish (RTND) to an atomic clock to decrease the uncertainty of the atomic clock beyond the level that is attained by the current controlling method. In RTND, the related parameters of the clock are monitored in real time by using the calibrated sensors, and their effects on the clock frequency are calculated. By subtracting the effects from the error signal, the local oscillator is treated as equivalently locked to the unperturbed atomic levels. In order to perform quantitative tests, we engineer time-varying noise much larger than the intrinsic noise in our fountain atomic clock. By using RTND, the influences of the added noises are detected and subtracted precisely from the error signals before feeding back to the reference oscillator. The result shows that the statistical uncertainty of our fountain clock is improved by an order of magnitude to 2×10?15. Besides, the frequency offset introduced by the noise is also corrected, while the systematic uncertainty is unaffected.
020.1335 Atom optics 120.3940 Metrology Chinese Optics Letters
2017, 15(5): 050201
Author Affiliations
Abstract
1 Key Laboratory of Quantum Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
A self-comparison method with closely interleaved switching states is analyzed and used to evaluate some type-B uncertainties of an Rb87 atomic fountain clock. Free from additional frequency reference, the method can be applied to a running fountain to reach a precision beyond its uncertainty. A verification experiment proves an uncertainty of 9.2×10 16 at an averaging time of 242500 s. Further, the method is applied to measure light shift, and no visible relative frequency shift is found in the fountain within the uncertainty of 2.1×10 15. When applied to the evaluation of a cold collisional shift, the result gives a 2.2×10 15 shift with a 9.5×10 16 uncertainty.
020.1335 Atom optics 120.3940 Metrology Chinese Optics Letters
2016, 14(8): 081201
Author Affiliations
Abstract
1 Key Laboratory of Quantum Optics, Center for Cold Atom Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
We report a locking mode in which the local oscillator (LO) is locked to an atomic fountain and calibration of the residual frequency drift (RFD). In this running mode, the locked LO outputs a standard frequency signal, and a short-term fractional frequency stability of 2.7×10 13τ 1/2 is achieved. Due to the frequency drift of the LO in free running mode, a systematic frequency bias, or RFD, exists after being locked by the atomic fountain. We analyze and measure the RFD with a value of 3(2)×10 16. A sectionalized post-process method is adopted to calibrate the RFD.
120.0120 Instrumentation, measurement, and metrology 270.0270 Quantum optics 120.3940 Metrology Chinese Optics Letters
2015, 13(9): 091201
