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Design and test of the microwave cavity in an optically-pumped Rubidium beam frequency standard 下载免费PDF全文
We are developing a compact rubidium atomic beam frequency standard with optical pumping and detection.The cavity for microwave interrogation is an important part of the clock.The cavity in our design is a Ramsey-type,E-bend one,which is the same as the conventional method in most cesium beam clocks.Requirements for the design are proposed based on the frequency shift associated with the cavity.The basic structure of the cavity is given by theoretical analysis and detailed dimensions are determined by means of electromagnetic field simulation with the help of commercial software.The cavity is manufactured and fabricated successfully.The preliminary test result of the cavity is given,which is in good agreement with the simulation.The resonant frequency is 6.835 GHz,equal to the clock transition frequency of87Rb,and the loaded quality factor is 500.These values are adjustable with posts outside the cavity.Estimations on the Ramsey line width and several frequency shifts are made. 相似文献
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数字化和小型化是铷原子频标(RAFS)发展的重要方向.在传统铷原子频标电路中,6 840 MHz微波信号与频率综合器产生的5.312 5 MHz信号进行混频,得到用于激励铷原子跃迁的6 834.687 5 MHz微波探寻信号.早期铷频标的频率综合器大量使用了分立的模拟器件,数字化程度低、参数优化工作繁杂、电路体积较大.目前常用直接数字频率合成器(DDS)方案直接产生5.312 5 MHz信号,但这种数字电路方案通常需要对10 MHz信号进行倍频,它存在频谱纯度较低、相位噪声高等缺点.本文介绍一种产生5.312 5 MHz信号的频率综合器解决方案,这种设计方案在应用DDS器件时无需使用10 MHz倍频电路,它具有频谱纯度较高、相位噪声低、输出频率和相位可调等优点. 相似文献
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A. V. Kozlovskiĭ 《Journal of Experimental and Theoretical Physics》2008,107(3):356-363
The dynamics of energy exchange between an atom moving in a high-Q cavity and the cavity field is analyzed by taking into account the Roentgen interaction. A two-level atom coupled to a Fock or coherent state of an optical or microwave cavity is considered. The mean cavity photon number required for high-frequency Doppler-Rabi oscillations to occur is relatively high for both Fock-and coherent-state cavity fields and increases with the atomic transition frequency. Conditions are found when the Roentgen interaction plays a key role in the Doppler-Rabi oscillations and must be taken into account, in addition to the conventional electric field-dipole interaction. 相似文献
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Md. Mijanur Rahman 《Optik》2011,122(8):660-665
A novel approach for representing logic states in the quantum nodes and transferring the states from one node to another is proposed. Both transmit and receive nodes consist of a rubidium atom (87Rb) placed at the center of a two-mode cavity. Representation of logic states by two subspaces of the space of 87Rb atom hyperfine states eliminates the need for the transmitting node to change logic state during logic transfer through Raman process. The atom is excited by simultaneous application of two laser beams - one for each subspace. Based on the logic state, the atom emits a photon of appropriate frequency and polarization through Raman process within the corresponding subspace. The emitted photon leaks out of the cavity, reaches the receiving node, and initiates logic dependent transitions there. A simulation platform is developed through the system Hamiltonians for transmit and receive nodes followed by the formulation of the time evolution of the density matrices for the nodes. The efficacy of the simulation approach is emphasized. 相似文献
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A cavity quantum electrodynamics (QED) based approach for transferring quantum state between quantum nodes has been proposed, wherein a rubidium (87Rb) atom trapped inside a two-mode optical cavity forms the quantum node and photons serve as the information carrier between two such nodes. Information is encoded into polarized photon states generated through the application of a system of lasers. The focus is made on the phase-space analysis of the approach, wherein two subspaces of the hyperfine energy levels with magnetic sub-levels of rubidium (87Rb) atom represent the logic states ‘0’ and ‘1’. The system of lasers initiates a cavity assisted Raman process which, in turn, generates a right- or left-circularly polarized photon depending on the logic state of the transmit node. Once the photon is received (at the receive node), the logic state of the transmit node is restored into the receive node through a cavity QED process. 相似文献
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We propose a method to test Bohr complemetarity with cavity QED techniques. It involves an atomic beam passing through two Ramsey zones and a nonresonant cavity initially filled with a strong coherent field. In the absence of the cavity field the probability of finding the atom in a definite state exhibits interference. Due to the dispersive atom-field interaction the paths by which the atom reach the definite state are remarked and thus the interference is destroyed. The associated quantum eraser is also presented. 相似文献
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Negativity has been adopted to investigate the entanglement in a system composed of a two-level atom and a two-mode cavity field. Effects of Kerr-like medium and the number of photon inside the cavity on the entanglement are studied. Our results show that atomic initial state must be superposed, so that the two cavityfield modes can be entangled. Moreover, we also conclude that the number of photon in the two cavity mode should be equal. The interaction between modes, namely, the Kerr effect, has a significant negative contribution. Note that the atom frequency and the cavity frequency have an indistinguishable effect, so a corresponding approximation has been made in this article. These results may be useful for quantum information in optics systems. 相似文献
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Engineering three-dimensional maximally entangled states for two modes in a bimodal cavity 下载免费PDF全文
An alternative scheme is proposed for engineering three-dimensional
maximally entangled states for two modes of a superconducting
microwave cavity. In this scheme, an appropriately prepared
four-level atom is sent through a bimodal cavity. During its passing
through the cavity, the atom is coupled resonantly with two cavity
modes simultaneously and addressed by a classical microwave pulse
tuned to the required transition. Then the atomic states are detected
to collapse two modes onto a three-dimensional maximally entangled
state. The scheme is different from the previous one in which two
nonlocal cavities are used. A comparison between them is also made. 相似文献
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时间频率基准装置——铯原子喷泉钟, 在标准时间产生和保持、基础物理研究中发挥了重要的作用. 介绍了铯原子喷泉钟的工作原理, 对影响其性能的各项噪声源和频移项给出了分析, 影响频率稳定度性能的主要因素为Dick 效应相关的原子团装载时间、微波激励源相位噪声和探测激光的频率噪声, 影响频率不确定性能主要频移项为: 黑体辐射频移、冷原子碰撞频移、腔相位分布频移和微波泄露频移; 总结和比较了当前具有先进性能的铯原子喷泉钟采用的技术; 介绍了铯原子喷泉钟的主要应用方向、空间冷原子铯钟的研制情况和光学频率原子钟进展. 相似文献
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Shi-Biao Zheng 《Optics Communications》2007,273(2):460-463
We propose a scheme to realize strong squeezing for a cavity field with a single three-level atom. In the scheme the atom is sent through the cavity initially filled with a coherent field. The atom dispersively interacts with the cavity field, which is displaced by a microwave resource during the interaction. Then, a selective measurement on the atom collapses the field to a superposition of an even coherent state with a vacuum state, which exhibits strong squeezing. The scheme can also be generalized to the two-mode case. 相似文献
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Xiaochi Liu 《中国物理 B》2022,31(4):43201-043201
We present a coherent population trapping clock system based on laser-cooled $^{87}$Rb atoms. The clock consists of a frequency-stabilized CPT interrogation laser and a cooling laser as well as a compact magneto-optical trap, a high-performance microwave synthesizer, and a signal detection system. The resonance signal in the continuous wave regime exhibits an absorption contrast of $\sim 50$%. In the Ramsey interrogation method, the linewidth of the central fringe is 31.25 Hz. The system achieves fractional frequency stability of ${2.4\times }{{10}}^{{-11}}/\sqrt \tau $, which goes down to ${1.8\times }{{10}}^{{-13}}$ at 20000 s. The results validate that cold atom interrogation can improve the long-term frequency stability of coherent population trapping clocks and holds the potential for developing compact/miniature cold atoms clocks. 相似文献
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A. V. Kozlovskiĭ 《Journal of Experimental and Theoretical Physics》2007,104(4):515-526
A numerical analysis of dispersive quantum nondemolition measurement of the photon number of a microwave cavity field is presented. Simulations show that a key property of the dispersive atom-field interaction used in Ramsey interferometry is the extremely high sensitivity of the dynamics of atomic and field states to basic parameters of the system. When a monokinetic atomic beam is sent through a microwave cavity, a qualitative change in the field state can be caused by an uncontrollably small deviation of parameters (such as atom path length through the cavity, atom velocity, cavity mode frequency detuning, or atom-field coupling constants). The resulting cavity field can be either in a Fock state or in a super-Poissonian state (characterized by a large photon-number variance). When the atoms have a random velocity spread, the field is squeezed to a Fock state for arbitrary values of the system’s parameters. However, this makes detection of Ramsey fringes impossible, because the probability of detecting an atom in the upper or lower electronic state becomes a random quantity almost uniformly distributed over the interval between zero and unity, irrespective of the cavity photon number. 相似文献
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Md. Mijanur Rahman 《Optik》2011,122(1):84-88
A novel approach for transferring logic states from one quantum node to other is proposed. Logic states ‘0’ and ‘1’ are represented by two subspaces of the hyperfine states space of rubidium atom (87Rb). The atom, placed at the center of a two-mode cavity, is excited by simultaneous application of two laser beams, one for each subspace. Based on the logic state of the atom, it makes a transition to a higher energy level within the corresponding subspace. When the atom relaxes back to a lower state within the subspace, a left- or right-circularly polarized photon is emitted depending on whether the initial state was logic ‘0’ or logic ‘1’. The polarized photon leaks out of the cavity, reaches the receive node and gets detected therein. Simulation results show the efficacy of the approach. 相似文献