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1.
Light-shift induced by two unbalanced spontaneous decay rates in EIT (CPT) spectroscopies under Ramsey pulse excitation 下载免费PDF全文
Xiaoyan Liu 《中国物理 B》2021,30(8):83203-083203
Light shift is important and inevitably affects the long-term stability of an atomic clock. In this work, considering two unbalanced branches of the spontaneous decay rate in a three-level system, we studied the frequency shifts of electromagnetically induced transparency (EIT) and coherent population trapping (CPT) clocks operating under the pulse sequence regime by numerically solving the Liouville density matrix equations. The results show that the frequency shifts are larger when the two branches of spontaneous emission rate are not equal compared to the equal case. In addition, in EIT-Ramsey, the effect of the unbalanced branches of the spontaneous decay rate and relaxations of low-energy states on the frequency shift is greater than that of Rabi frequency. In CPT-Ramsey, the relaxations of low-energy states play a dominant role in frequency shift. 相似文献
2.
We measure the signal amplitude and linewidth of a dark line in coherent population trapping in the Rb vapour cell filled with mixed buffer gas N2 and Ar as a function of cell temperature. We find that the dark line signal amplitude increases with temperature up to a maximum at 49℃ and then drops at higher temperatures due to quenching effects of N2. The linewidth of the dark line remains basically constant, at 1080 Hz. We also measure the linewidth of the dark line as a function of laser intensity. The linewidth increases linearly with laser intensity. An intrinsic linewidth (FWHM=896 Hz at 3.4 GHz) of the Rb cell is obtained. 相似文献
3.
We report the observation of bichromatic coherent population trapping under the transition ^87 RbFg = 1 → Fc = 0 with two linearly polarized laser beams by means of a Hanle effect configuration. The mechanism behind this effect is identified, and numerical solutions for the pump rates equations are presented. 相似文献
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5.
Transparency and Strong Gain Without Population Inversion in Photonic Bandgap Crystals 总被引:1,自引:0,他引:1 下载免费PDF全文
Without using the weak-field approximation,we investigate the transient properties of a Λ-type atom with one transition near resonant with a photonic bandgap edge.Whatever the initial state of the atom is,the atom can become transparent to a probe field,and strong gain without population inversion is also possible if the atom has been pre-excited.The defect mode formed by atomic doping can have a strong effect on the absorption properties of the atom. 相似文献
6.
We have numerically investigated the biphoton generation rate as a function of several parameters in the spontaneous four-wave mixing in cold atoms.It has been found that the biphoton generation rate can easily reach saturation with the intensity of the coupling laser increasing.The saturation intensity is mainly dependent on the dephasing rate of the ground states,unrelated to the pumping laser.It implies that though the biphoton waveform can be manipulated by the coupling laser,the generation rate of the biphoton cannot increase markedly after the saturation.The saturation effect also suggests that there is an optimal coupling laser for obtaining the largest biphoton generation rate with a sufficiently long coherence time. 相似文献
7.
Considering all the ground-state atom interactions,we investigate the population transfer of two Bose-Einstein condensate (BEC) states,which are trapped in diffecent potential wells,or two ground states of the BEC in the same trap using the stimulated Raman adiabatic process.With a proper choice of pulsed geometric parameters,the dark state exists.By simply choosing ground-state detunings,the effects of the interatomic interaction can be suppressed and a high population transfer rate can be obtained. 相似文献
8.
We have investigated the dispersive properties of excited-doublet four-level atoms interacting with a weak probe field and an intense coupling laser field. We have derived an analytical expression of the dispersion relation for a general excited-doublet four-level atomic system subject to a one-photon detuning. The numerical results demonstrate that for a typical rubidium D1 line configuration, due to the unequal dipole moments for the transitions of each ground state to double excited states, generally there exists no exact dark state in the system. Close to the two-photon resonance, the probe light can be absorbed or gained and propagate in the so-called superluminal form. This system may be used as an optical switch. 相似文献
9.
We have proposed a model of periodic axial magnetized hollow tube for atom guidance (1999 Opt. Commun. 160 72-4). In the present paper, an analytic solution of the magnetic field inside the tube is obtained and the transport efficiency of the cold atoms in the magnetic tube at different tube intensities of magnetization is discussed. The effect of the curvature of magnetic tube on the atom transport efficiency is also considered. We have found that the tube has a cooling effect on the transverse temperature of the transported atoms. 相似文献
10.
Transient coherent oscillations in a closed Λ system under far-off resonant Raman fields were investigated theoretically. It has been found that the coherent superposition of the ground states can be formed due to the absorption even for initial maximal mixed ground states. The absorption oscillates with a period depending on the two-photon detuning when the system is initially in a transparent state and the two-photon Raman detuning is suddenly changed. The amplitude of the absorption decays with the decay rate of the ground states, which is different from the case when the lasers are applied resonantly. These transient coherent oscillations can be used to measure the relaxation rate of the ground states. 相似文献