Chinese Optics Letters, 2017, 15 (4): 040201, Published Online: Jul. 25, 2018
Recent improvements on the pulsed optically pumped rubidium clock at SIOM Download: 1224次
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Fig. 1. (a) Schematic setup of the POP clock with dispersive detection. PD, photodetector. (b) Timing sequence for the POP clock. Top red, optical pulses for state preparation and detection; middle blue, two microwave pulses for Ramsey interrogation; bottom yellow, trigger pulse for signal acquisition. These pulses correspond to the switches in different colors in (a). (c) Detailed energy level structure of Rb 87 involved in the POP clock. The π transition between | 5 2 S 1 / 2 , F = 1 , m F = 0 〉 and | 5 2 S 1 / 2 , F = 2 , m F = 0 〉 is chosen as the clock transition with a frequency of about 6.8346 GHz.
Fig. 2. (a) Schematic of the new physics package. The cell filled with Rb 87 and buffer gases has a size of ϕ 20 × 20 mm fixed in a TE 011 microwave cavity resonant at 6.8 GHz. The size of the physics package is about ϕ 130 × 170 m m with a volume of about 2.2 L. (b) Microwave–light double resonance signal. The three peaks correspond to the π transitions (Δ m F = 0 ) between hyperfine levels of Rb 87 . (c) Ramsey oscillating signal. We fixed the microwave frequency on the clock transition frequency and measured the Ramsey signal by changing the microwave power. (d) Ramsey fringe measured with the new physics package. The fringe has a contrast of about 97%, an SNR of about 2400, and a line width of about 140 Hz.
Fig. 3. (a) Fractional frequency under different temperatures. Black square, experimental data; red curve, fit line. (b) Temperature stability in terms of the Allan deviation and the Hadamard deviation under different average times.
Fig. 4. Frequency stability of the POP clock compared with the H maser. A drift of about − 4.5 × 10 − 13 / day is removed from the data. A clock frequency stability of 3.53 × 10 − 13 at 1 s is obtained, and the medium-term fractional frequency stability of 4.91 × 10 − 15 is achieved at an averaging time of τ = 2000 s .
Gongxun Dong, Jianliao Deng, Jinda Lin, Song Zhang, Haixiao Lin, Yuzhu Wang. Recent improvements on the pulsed optically pumped rubidium clock at SIOM[J]. Chinese Optics Letters, 2017, 15(4): 040201.