Microwave Frequency Standards Using New Physics

2015 ◽  
pp. 211-364
Keyword(s):  
Microwave Frequency ◽  
New Physics ◽  
Frequency Standards

Ultracold atoms and precise time standards

2011 ◽  
Vol 369 (1953) ◽  
pp. 4078-4089 ◽  
Author(s):  
Gretchen K. Campbell ◽  
William D. Phillips
Keyword(s):  
Laser Cooling ◽  
International System ◽  
Microwave Frequency ◽  
Observation Time ◽  
Mass Motion ◽  
Frequency Standards ◽  
Systematic Uncertainties ◽  
System Of Units ◽  
Time Standards ◽  
Atomic Frequency

Experimental techniques of laser cooling and trapping, along with other cooling techniques, have produced gaseous samples of atoms so cold that they are, for many practical purposes, in the quantum ground state of their centre-of-mass motion. Such low velocities have virtually eliminated effects such as Doppler shifts, relativistic time dilation and observation-time broadening that previously limited the performance of atomic frequency standards. Today, the best laser-cooled, caesium atomic fountain, microwave frequency standards realize the International System of Units (SI) definition of the second to a relative accuracy of ≈3×10 −16 . Optical frequency standards, which do not realize the SI second, have even better performance: cold neutral atoms trapped in optical lattices now yield relative systematic uncertainties of ≈1×10 −16 , whereas cold-trapped ions have systematic uncertainties of 9×10 −18 . We will discuss the current limitations in the performance of neutral atom atomic frequency standards and prospects for the future.

Microwave frequency standards

1948 ◽  
Vol 67 (5) ◽  
pp. 436-439
Author(s):  
B. F. Husten ◽  
Harold Lyons
Keyword(s):  
Microwave Frequency ◽  
Frequency Standards

scholarly journals Cascaded Microwave Frequency Transfer over 300-km Fiber Link with Instability at the 10−18 Level

2021 ◽  
Vol 13 (11) ◽  
pp. 2182
Author(s):  
Wenxiang Xue ◽  
Wenyu Zhao ◽  
Honglei Quan ◽  
Yan Xing ◽  
Shougang Zhang
Keyword(s):  
Cold Atom ◽  
Microwave Frequency ◽  
Propagation Delay ◽  
Noise Power ◽  
Noise Power Spectral Density ◽  
Frequency Standards ◽  
Power Spectral ◽  
Electronic Phase ◽  
Frequency Transfer ◽  
Cascaded System

Comparing and synchronizing atomic clocks between distant laboratories with ultra-stable frequency transfer are essential procedures in many fields of fundamental and applied science. Existing conventional methods for frequency transfer based on satellite links, however, are insufficient for the requirements of many applications. In order to achieve high-precision microwave frequency transfer over a thousand kilometers of fiber and to construct a fiber-based microwave transfer network, we propose a cascaded system for microwave frequency transfer consisting of three 100-km single-span spooled fiber links using an improved electronic phase compensation scheme. The transfer instability measured for the microwave signal reaches 1.1 × 10−14 at 1 s and 6.8 × 10−18 at 105 s, which agrees with the root-sum-square of each span contribution. It is feasible to extend the length of the fiber-based microwave frequency transfer up to 1200 km using 4 stages of our cascaded system, which is still sufficient to transfer modern cold atom microwave frequency standards. Moreover, the transfer instability of 9.0 × 10−15 at 1 s and 9.0 × 10−18 at 105 s for a 100-MHz signal is achieved. The residual phase noise power spectral density of the 300-km cascaded link measured at 100-MHz is also obtained. The rejection frequency bandwidth of the cascaded link is limited by the propagation delay of one single-span link.

scholarly journals Prospective directions for the development of microwave frequency standards for satellite navigation systems

2021 ◽  
Vol 2086 (1) ◽  
pp. 012073
Author(s):  
Ding Wang ◽  
V V Davydov ◽  
V Yu Rud
Keyword(s):  
Time Synchronization ◽  
Microwave Frequency ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Navigation Systems ◽  
Satellite Systems ◽  
Frequency Standards ◽  
Global Navigation ◽  
Satellite Navigation Systems ◽  
Global Navigation Satellite

Abstract The state of essential various quantum standards of GNSS frequencies for today are collected and presented, the results of analysis in the direction of modernization of time synchronization systems in global navigation satellite systems are presented. The most perspective directions of modernization of global navigation satellite systems are mentioned – the development of new atomic clocks on the mercury ions -199. The data on experimental satellite gives encouraging results.

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