Towards a High Duty Cycle Transportable 171Yb Clock

Fatima Rahmouni, Jesús Romero González, Benjamin Pointard +2 more

Xuanjian Wang, Jian Zhong Cao, Hualin Shu +5 more

Filip Butuc-Mayer, Matthew Johnson, Chen-Hao Feng +3 more

Abstract We describe a method of duty cycle engineering in optical lattice clocks to reduce clock instability through tailoring of the Dick effect noise contribution. We apply dynamically decoupled interrogation sequences to realise an estimated improvement in single clock instability approaching a factor of two, as well as providing a route to zero dead-time operation for two interleaved clocks which are otherwise unable to reach the required duty cycle. We show through simulations and synchronous measurements of clocks NPL-Sr1 and NPL-Sr2 that a quantum projection noise limited instability < 3 − 10−17 τ −1/2 can be realised in a near ideal zero dead-time configuration.

Fatima Rahmouni, Jesús Romero González, Benjamin Pointard +10 more

Jun Zhang, Zhen-Jie Gu, Peng Qian +2 more

We present a cold atom system with a dark-line two-dimensional magneto-optical trap, to increase the atomic density by suppressing the atomic radiation pressure. Optical depth (OD) and duty cycle are used to evaluate the system performance. We demonstrate a 100% increase in OD with the dark line, and obtain an ultrahigh OD of 264 with 10% for the duty cycle. Also, with an efficient dark line region, the OD could maintain above 100 with duty cycle as high as 30%. The cold atomic ensemble with an ultrahigh OD with a 10%–30% duty cycle is particularly advantageous in quantum information processing and communication.

Jingjing Xia, Xiaotong Lu, Hong Chang

The optical Ramsey spectrum is experimentally realized in an 87Sr optical lattice clock, and the measured linewidth agrees well with theoretical expectation. The coherence time between the clock laser and the atoms, which indicates the maximum free evolution period of using Ramsey detection to measure the atom-laser phase information, is determined as 340(23) ms by measuring the fringe contrasts of the Ramsey spectrum as a function of the free evolution period. Furthermore, with the same clock duty cycle of about 0.1, the clock stability is measured by using the Ramsey and Rabi spectra, respectively. The experimental and theoretical results show approximately the same stability as the two detection methods, which indicates that Ramsey detection cannot obviously improve the clock stability until the clock duty cycle is large enough. Thus, it is of great significance to choose the detection method of a specific clock.