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1.
Collective coupling of multiple atoms with a cavity mode produces two normal modes that are separated in energy by Vacuum
Rabi splitting. We show that quantum coherence and interference can be produced by a control laser that couples the atoms
confined in the cavity mode from free space, which leads to suppression of the normal mode excitation, or polariton excitation
of the cavity-atom system. The control laser splits the normal mode of the cavity-atoms system and opens two excitation channels.
The destructive quantum interference between the two channels renders the cavity-atoms system opaque to the light coupled
into the cavity mode. We demonstrate suppression of the normal mode (polariton) excitation by the destructive quantum interference
in an experiment with cold Rb atoms confined in an optical cavity. 相似文献
2.
利用含时波包法研究三激光场中四态阶跃型K2分子光电子能谱的Autler-Townes(AT)分裂.研究第二束激光场强和波长对AT分裂的影响.共振时,光电子谱为对称三分裂,非共振时,不对称三分裂逐渐变为双分裂.波长增加,谱峰以不等位移向低能方向移动.边峰间距不随波长的改变而改变,随场强增强而增大.研究结果为进一步从第一性原理的理论研究提供有用的信息,为实现分子的光控制及量子调控提供重要参考. 相似文献
3.
We investigate photon-number dependent cavity vacuum induced transparency and magneto-optical rotation (MOR) in a cavity quantum electrodynamics system, which consists of two cavities and an ensemble of Λ-type atoms. We demonstrate that the probe photon coupled into one cavity can be transferred to the mode of another cavity via coherent Raman scattering. The transmission, the phase shift, as well as the vacuum Rabi splitting therefore strongly depend upon the probe photon number coupled into the cavity. The photon number dependent cavity vacuum induced transparency can be extended into four-level tripod atoms, leading to photon-number dependent MOR. This can be used to separate the single photon from higher photon number components in the direction of polarization and create a deterministic single photon source. 相似文献
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6.
C. Mavroyannis 《Applied physics. B, Lasers and optics》2001,73(1):39-50
We have considered the interference spectra that occur at the three-photon generated frequency arising from the interaction
of three laser fields with a four-level atom, where two of the laser fields are on two-photon resonance with the three levels
forming a “λ” scheme while the third laser operates between the second ground and the second excited state of the atom. At
low intensities of all three laser fields, the overall intensity of the peak at the three-photon generated frequency, describing
the spectrum of an electron in the second excited state, depends on the strength of the combined field of the two laser fields
that are on two-photon resonance and it takes negative values. This indicates that light amplification without population
inversion is likely to occur at the three-photon generated frequency. The combined field of the three laser fields induces
multiphoton excitations near the three-photon generated frequency, whose peaks are characterized by linewidths which are much
less than the natural linewidths of the atoms. These excitations describe absorption or stimulating emission processes depending
on the values of the detunings of the laser fields. The derived results are graphically presented and discussed.
Received: 24 January 2001 / Published online: 8 June 2001 相似文献
7.
Intra-cavity phase anisotropy causes each laser longitudinal mode to split into two orthogonally polarized frequencies. When the frequency difference generated by small anisotropy is about 40 MHz or less, only one frequency of the splitting mode oscillates while the other is always in lock-in state due to strong mode competition. In that case the longitudinal mode spacing deviates from its original value. And the spacing of two adjacent longitudinal modes shows differential variations depending on direction of cavity length tuning and mode polarization. In this paper, the relationship between spacing variation and small intra-cavity anisotropy is demonstrated experimentally and theoretically. The equivalent fast axis of anisotropy is determined additionally by its correlation with laser intensity tuning of the two orthogonally polarized components. The novel measurement method is successfully tested in several applications. 相似文献
8.
We report an experimental study of resonant six-wave mixing in coherently prepared Rb atoms. Electromagnetically induced transparency in a four-level atomic system suppresses the linear susceptibility and enhances the nonlinear susceptibilities, which leads to the resonantly enhanced, slow-photon six-wave mixing at low light intensities. The light emission in the six-wave mixing process can be viewed as resulting from diffraction of slow light off a resonant nonlinear grating induced in the four-level system by a standing-wave pump field. 相似文献
9.
M.A. Antón 《Optics Communications》2011,284(5):1262-1273
We theoretically examine the storage and retrieval of a light pulse in a medium comprised of four-level atoms of the V − Λ-type. The two intermediate levels are probed by a weak field and vacuum-induced coherence effects lead the system to transparency. The temporal variation of the intermediate levels' splitting is used as an external parameter which allows the transfer of the impinging field to a combination of spin coherences. An auxiliary and far-detuned control field in a standing-wave configuration is used to induce a variable photonic bandgap by cross-phase modulation. It is shown that dynamic control of such a bandgap can be used to coherently manipulate the previously stored probe pulse. We use a general scheme to take into account multiwave mixing effects and solve the combined Maxwell-Bloch equations for the relevant coherences. It is shown that the system acts as an all-optical router. 相似文献
10.
Tunable optomechanically induced transparency and fast–slow light in a loop-coupled optomechanical system
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《中国物理 B》2021,30(9):94205-094205
We theoretically explore the tunability of optomechanically induced transparency(OMIT) phenomenon and fast–slow light effect in a loop-coupled hybrid optomechanical system in which two optical modes are coupled to a common mechanical mode. In the probe output spectrum, we find that the interference phenomena OMIT caused by the optomechanical interactions and the normal mode splitting(NMS) induced by the strong tunnel coupling between the cavities can be observed. We further observe that the tunnel interaction will affect the distance and the heights of the sideband absorption peaks. The results also show that the switch from absorption to amplification can be realized by tuning the driving strength because of the existence of stability condition. Except from modulating the tunnel interaction, the conversion between slow light and fast light also can be achieved by adjusting the optomechanical interaction in the output field. This study may provide a potential application in the fields of high precision measurement and quantum information processing. 相似文献
11.
Yu-Yuan Chen Zhuan-Zhuan Liu Ren-Gang Wan 《International Journal of Theoretical Physics》2017,56(10):3117-3128
We propose a scheme for creating electromagnetically induced grating in a four-level double- Λ atomic system driven by a coupling field and an incoherent pump field. Owing to the incoherent pumping process, large refractivity accompanied with vanishing absorption or even gain across the probe field can be built up in the atoms, thus phase grating or gain-phase grating, which diffracts a probe light into different directions, can be formed with the help of a standing-wave coupling field. The diffraction efficiency of the gratings can be tuned by the coupling field intensity and the incoherent pump rate, hence the proposed gratings should be suitable for beam splitter and optical switching in optical communication and networking. 相似文献
12.
E. Silveira 《Solid State Communications》2011,151(11):846-849
Raman spectroscopy is used here to study pseudomorphic Si0.989C0.011/Si superlattices grown by molecular beam epitaxy. The high crystalline quality of the samples was tested by a high resolution X-ray diffraction experiment. The lineshape of the LO Si-Si peak shows an asymmetry, which correlates with the increase of the alloy layer width. The Raman spectra show three additional peaks in the high energy side above the LO mode of Si. One of them is due to the local vibration of the C substitutional atoms, and the other two can be attributed to the formation of short range order with C atoms occupying second and third nearest-neighbor places. On the low energy side of the LO Si-Si mode, we have observed two other peaks associated with the relaxation of the Si atoms around the substitutional C. Although the X-ray experiments show clear evidence of superperiodicity, no indication of the superlattice formation could be observed in the parallel polarized Raman spectra, where the folded acoustic modes are allowed. 相似文献
13.
The mode hopping phenomenon induced by optical feedback in single-mode microchip Nd:YAG lasers is presented. With optical feedback, mode hopping strongly depends on two factors: the ratio of external cavity length to intra-cavity length, and initial gains of the two hopping modes, When external cavity length equals an integral multiple of intracavity length, there is almost no mode hopping. However, if the external cavity length does not equal an integral multiple of intra-cavity length, mode hopping occurs. The ratio of external cavity length to intra-cavity length determines the position of two-mode hopping, The initial gains of the two hopping modes determine the corresponding peak values and oscillating periods of them in the intensity modulation curves. 相似文献
14.
The phenomenon of coherent population trapping for a four-level model of alkaline atoms with optical pumping by nonresonant
light is analytically investigated. Expressions for experimentally observed signals are derived for different variants of
induced magnetodipole transitions in the hyperfine structure of the ground state of atoms within the density matrix formalism.
No light-induced frequency shift of the signal of radio-optical resonance is observed irrespective of the radio field amplitude
and optical and thermal relaxation rates. It is demonstrated that with the use of modulation technique of phase detection
of experimentally observed signal, its discrimination power reaches a maximum under conditions of simultaneous modulation
of the pumping light intensity and radio-field frequency, which in principle is not observed in the classical two-level model
of optically oriented atoms in the magnetic resonance.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 12–16, August, 2006. 相似文献
15.
用紫外光电子能谱(UPS)研究了酞菁铜分子在Ag(110)单晶表面上的吸附,随着酞菁铜分子覆盖度增加,衬底Ag的3d电子信号逐渐减弱,在此能带区域出现两个新的谱峰,这两个与吸附有机分子轨道有关的谱峰的束缚能分别为4.45 和6.36 eV.随着覆盖度的增加,在结合能为1.51和9.20 eV处又出现了两个谱峰,它们同样来自吸附有机分子的轨道.随着覆盖度的继续增加,上述四个谱峰的强度逐渐增加,其能量位置均发生了明显的偏移.根据角分辨光电子能谱的实验结果,酞菁铜分子的分子平面基本与衬底表面平行.密度泛函理论计
关键词:
酞菁铜
紫外光电子谱
吸附电子态
密度泛函理论 相似文献
16.
An analytical model for cross-Kerr nonlinearity in a four-level N-type atomic system with Doppler broadening
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Dinh Xuan Khoa Nguyen Huy Bang Nguyen Le Thuy An Nguyen Van Phu Le Van Doai 《中国物理 B》2022,31(2):24201-024201
We present an analytical model for cross-Kerr nonlinear coefficient in a four-level N-type atomic medium under Doppler broadening.The model is applied to87 Rb atoms to analyze the dependence of the cross-Kerr nonlinear coefficient on the external light field and the temperature of atomic vapor.The analysis shows that in the absence of electromagnetically induced transparency(EIT)the cross-Kerr nonlinear coefficient is zero,but it is significantly enhanced when the EIT is established.It means that the cross-Kerr effect can be turned on/off when the external light field is on or off.Simultaneously,the amplitude and the sign of the cross-Kerr nonlinear coefficient are easily changed according to the intensity and frequency of the external light field.The amplitude of the cross-Kerr nonlinear coefficient remarkably decreases when the temperature of atomic medium increases.The analytical model can be convenient to fit experimental observations and applied to photonic devices. 相似文献
17.
利用阳光直接将水分解为不含碳的氢气燃料和氧气是面向全球能源危机环保且低成本的解决方案.得益于电子结构理论和量子模拟方法的进步,人们已经能够直接研究在纳米颗粒上等离激元诱导光解水过程在原子尺度上的反应机理和超快动力学.本文简述近年来的相关工作进展.吸附在氧化物薄膜上的金纳米颗粒很有希望成为水分解的高效新型光催化剂.在光激发条件下,水分解反应速率和光强、热电子转移之间有强相关性.水分解速率不仅取决于光吸收强度,还受到等离激元量子振动模式的调控.这对于太阳能光解水器件中纳米颗粒的设计有借鉴意义.我们发现液态水在金团簇等离激元催化下100 fs内就能产生氢气.超快量子动力学模拟表明,该过程中场增强起主导作用,从金属到水反键态的超快电荷转移也扮演着重要角色.综合这些原子尺度上的量子动力学研究,我们提出受激水分子中氢原子高速碰撞(速度远远超出其热速度)合成氢分子的"链式反应"机理. 相似文献
18.
D. Naidoo K. A?t-Ameur M. Brunel A. Forbes 《Applied physics. B, Lasers and optics》2012,106(3):683-690
In this paper we demonstrate experimentally the intra-cavity generation of a coherent superposition of Laguerre–Gaussian modes
of zero radial order but opposite azimuthal order. The superposition is created with a simple intra-cavity stop that creates
equal losses for the two azimuthal modes, and we show that by adjustment of the stop we can produce modes up to azimuthal
order 8. The fact that we have a coherent superposition rather than an incoherent superposition is verified by intensity measurements,
propagation measurements and a decomposition of the field by an inner product executed on a phase-only spatial light modulator.
Such fields have relevance in quantum information and optical trapping. 相似文献
19.
We propose a novel scheme for light amplification and gain equalization by
quantum interference. We find that the laser amplification can be observed at
three specific probe frequencies in a four-level system. Furthermore, we
show that three gain peaks can be combined into one to obtain
gain equalization. 相似文献
20.
Yadlowsky E.J. Hazelton R.C. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(1):24-29
Faraday rotation of a laser beam and emission spectroscopy to resolve Zeeman splitting provide information about the plasma magnetic field, integrated along the line of sight. Information about the local magnetic field strength can be obtained using a dye laser tuned off the center of an atomic or ionic transition by an amount δλz. If the absorption linewidth of the transition probed is less than the Zeeman splitting, only those atoms/ions residing in a magnetic field where the Zeeman splitting is δλz will resonantly absorb energy from the laser and fluoresce. The feasibility of this magnetic field contour technique was studied in a low-pressure neon discharge. A conductor insulated from the discharge generated a large magnetic field in the discharge free of the Stark broadening effects associated with large plasma currents. The laser-induced fluorescence (LIF) intensity profile measured along the laser beams had peaks at those spatial locations where local magnetic fields, inferred from the conductor current, agreed with the Zeeman shifted wavelength of the laser 相似文献