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The predictability of atomic clock is generally used to characterize its overall performance. Anomalous clock behaviors lead to greater prediction error in traditional prediction method, such as polynomial fitting predictor and Kalman filter predictor. Our previous work developed random pursuit strategy (RPS) to avoid or minimize above the problem. It was further applied to real data of three Hydrogen...
We investigated the thermal management design of microfabricated vapor cells by putting forward three wiring patterns. A theoretical model and a simulated analysis were implemented to optimize heating and temperature-measuring wiring patterns on the cell surface. The optimal pattern is able to maintain heating efficiency, optical transparence and weak additional electromagnetic field to ∼nT level...
A compact laser pumped vapor-cell cesium clock is introduced. The microwave cavity design is essential to the performance of the clock. In order to get a great homogeneity of the magnetic field, we use a compact magnetron cavity, which meanwhile reduces the size of physics package. Theoretical analysis shows the basic structure of the magnetron cavity, which is proved and further optimized by software...
We report here the performance obtained with a laboratory compact caesium clock based on coherent population trapping (CPT). The clock is working with two orthogonal linear polarizations made by two phase-locked continuous lasers tuned to 895 nm and separated by 9192 MHz. Since the Local Oscillator (LO) noise and the laser relative intensity noise (RIN) are the two main noise source contributions...
Atomic clocks based on coherent population trapping and constructive polarization modulation are promising for their high performance and compactness. Here we demonstrate the feasibility toward an even more compact atomic clock design.
We propose a frequency drift detection method for coherent population trapping (CPT) atomic clocks to improve their long-term frequency stability. One of the main reasons for frequency drift in gas-cell based atomic clocks is buffer gas pressure variations in the gas cells caused by leakage through the cell walls. In this work, the drift detection method is demonstrated experimentally using a dual...
This paper report the microfabrication process of cesium (Cs) vapor cells using low-temperature wafer bonding process and its activation by a krypton fluoride (KrF) excimer laser. Low-temperature process with sequential plasma process for Si/glass anodic bonding enables to encapsulate cesium azide (CsN3) in the cell below its melting point and reduce presence of impurities inside the cavities, leading...
High performance compact microwave atomic clocks are on great demand in many areas. Different schemes are proposed to improve the performance and minimize the size of an atomic clock. Vapor cell atomic clocks based on Ramsey-CPT (coherent population trapping) are very promising due to its simple all optical configuration. In this paper, we report an integrated electronic controller based on a FPGA...
The Dick effect is one of the main limits for a passive atomic frequency standard to reach its frequency instability limit due to quantum projection noise. In this paper, we report on the reduction of Dick effect of a Ramsey-CPT vapor cell clock using interleaving lock. Three parameters are investigated in the process of optimizing sensitivity function in details. By optimizing the sensitivity function,...
A compact caesium-atomic-beam microwave clock is investigated at Peking University. The atomic beam is prepared by magnetic state selection and detected, after microwave interrogation, by means of laser-induced fluorescence. Distributed feedback laser diodes are adopted for their large mode-hopping-free ranges, which ensure a care-free long-term operation. Besides, digital servo systems can automatically...
The NAC1 (“Nano-Atomic-Clock”) is a miniature, high reliability, CPT-based Rubidium Atomic clock. Its basic design and features were described in a previous paper. This paper provides further details and updates on the clock. In particular we focus on medium-term and long-term stability issues that are key parameters in commercial atomic clocks, as well as the wide temperature operational range and...
We present an improved model relating the frequency shift between 133Cs hyperfine Zeeman substates to the Lorentz-violating coefficients of the Standard-Model Extension (SME) framework. This model is based on a second order boost Lorentz transformation, which enables us to constrain the isotropic coefficient CTT. It also takes into account the nuclear structure, beyond the usual Schmidt model, extending...
We propose a low temperature process of alkali-metal vapor cells for microfabricated atomic clocks using alkali-metal source tablets (AMSTs) as alkali metal dispensers. An AMST contains precise quantities of cesium aside (CsN3) inside the porous alumina that is used to produce of Cs by thermal decomposition of CsN3. The AMST technology together with sequential plasma activated Si/glass bonding is...
We present the current status of the Sr+ optical atomic ion clock at the National Research Council of Canada including the study of the quantum projection noise (QPN) limited stability and the progress on the evaluation of the blackbody radiation (BBR) shift uncertainty. The latest QPN limited stability of NRC's Sr+ clock is 3 × 10−15 at 1 sec averaging time. The fractional evaluated accuracy of the...
We describe progress at NIST to develop a series of “chip-scale”, SI-traceable electromagnetic reference instruments based on microfabricated alkali vapor cells. We anticipate being able to realize the second, the meter, the volt, the ampere and the kelvin using microfabrication techniques and spectroscopic measurement of alkali atom energy levels. We report here on initial fabrication efforts to...
While phasor measurement units (PMUs) are used primarily in transmission networks, researchers envisage using them in distribution networks. The rapid proliferation of renewable sources in distribution networks introduces volatility that could be compensated with storage elements. The active control of these storage devices requires the knowledge of the system state based on frequent PMU measurements...
In this paper, we propose a dual-mode Ramsey cavity for a dual Rb/Cs atomic clock, with resonances at 6.83GHz and 9.19GHz under the two different operating modes, respectively. Thus, the proposed cavity can excite Rb atoms and Cs atoms clock transition in the same environment (e.g., static magnetic field, temperature, and/or the asymmetric length between the two arms due to a single U-shaped structure)...
We demonstrate a synchronously stimulation method for achieving coherent population beating (CPB) atomic clock with the CPB signal which have continuous wave and higher signal-to-noise ratio. In this method we synchronously apply the coherent population trapping (CPT) resonant stimulating lights together with the detuned detecting lights to obtain continuous CPB oscillation signal. Under the stimulation,...
A lin-par-lin Ramsey-CPT microwave atomic clock with dispersion detection is investigated in this paper, in which high signal contrast and narrow linewidth are obtained. The pulsed transmitted laser is synchronously detected by a sample-and-hold amplifier and a lock-in amplifier. The frequency shift of the microwave, represented by the output of the lock-in amplifier is acquired. An instability is...
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