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1.
Optical absorption in asymmetric double quantum wells driven by two intense terahertz fields
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Optical absorption is investigated for asymmetric double quantum wells driven by a resonant terahertz field and a varied terahertz field both polarized along the growth direction. Rich nonlinear dynamics of the replica peak and the Autler-Townes splitting of various dressed states are systematically studied in undoped asymmetric double quantum wells by taking account of multiple factors, such as the frequency of the varied terahertz field and the strength of the resonant terahertz field. Each electron subband splits into two dressed states when the resonant terahertz field is applied in the absence of the varied terahertz field, the optical absorption spectrum shows the first order Autler-Townes splitting of the electron subbands. When a varied terahertz field is added into the resonant system, the replica peak and the second order Autler-Townes splitting of the dressed states near the band edge respectively emerge when the varied terahertz field is non-resonant and resonant with these dressed states. When the strength of the resonant terahertz field is increased, the first order Autler-Townes double peaks and the replica peak in the optical absorption spectrum shift with the shifts of the dressed states. The presented results have potential applications in electro-optical devices. 相似文献
2.
利用含时量子波包法理论研究了分子在强激光场条件下的量子调控.选取K2分子的三态模型(基态|X〉、激发态|B〉和电离态|X+〉)作为研究对象.在强激光场的作用下,激发态|B〉缀饰成两个子态:|α〉态和|β〉态.分析K2分子电离后的光电子能谱,可以得到缀饰态|α〉和|β〉的能量和概率分布信息.同时,根据分子的缀饰态理论,提出了K2分子的缀饰态选择性分布方案.研究表明:调节激光场的强度可以实现对缀饰态能量的调控,改变激光场的波长可以实现对缀饰态概率的选择性分布. 相似文献
3.
Pupillo G Griessner A Micheli A Ortner M Wang DW Zoller P 《Physical review letters》2008,100(5):050402
We study the realization of lattice models, where cold atoms and molecules move as extra particles in a dipolar crystal of trapped polar molecules. The crystal is a self-assembled floating mesoscopic lattice structure with quantum dynamics given by phonons. We show that within an experimentally accessible parameter regime extended Hubbard models with tunable long-range phonon-mediated interactions describe the effective dynamics of dressed particles. 相似文献
4.
Wilson CM Duty T Persson F Sandberg M Johansson G Delsing P 《Physical review letters》2007,98(25):257003
We measure longitudinal dressed states of a superconducting qubit, the single Cooper-pair box, and an intense microwave field. The dressed states represent the hybridization of the qubit and photon degrees of freedom and appear as avoided level crossings in the combined energy diagram. By embedding the circuit in an rf oscillator, we directly probe the dressed states. We measure their dressed gap as a function of photon number and microwave amplitude, finding good agreement with theory. In addition, we extract the relaxation and dephasing rates of these states. 相似文献
5.
We present a theoretical analysis of the implementation of an entangling quantum gate between two trapped Ca+ ions which is based on the dipolar interaction among ionic Rydberg states. In trapped ions, the Rydberg excitation dynamics is usually strongly affected by mechanical forces due to the strong couplings between electronic and vibrational degrees of freedom in inhomogeneous electric fields. We demonstrate that this harmful effect can be overcome using dressed states that emerge from the microwave coupling of nearby Rydberg states. At the same time. these dressed states exhibit long-range dipolar interactions which we use to implement a controlled adiabatic phase gate. Our study highlights a route toward a trapped ion quantum processor in which quantum gates are realized independently of the vibrational modes. 相似文献
6.
Duan LM 《Physical review letters》2005,95(24):243202
We derive the Hamiltonian for cold fermionic atoms in an optical lattice across a broad Feshbach resonance, taking into account both multiband occupations and neighboring-site collisions. Under typical configurations, the resulting Hamiltonian can be dramatically simplified to an effective single-band model, which describes a new type of resonance between the local dressed molecules and the valence bond states of fermionic atoms at neighboring sites. On different sides of such a resonance, the effective Hamiltonian is reduced to either a t-J model for the fermionic atoms or an XXZ model for the dressed molecules. The parameters in these models are experimentally tunable in the full range, which allows for observation of various phase transitions. 相似文献
7.
We consider dynamics of a two-component Bose–Einstein condensate, where the components correspond to different hyperfine states of the same sort of atoms. External microwave radiation leads to resonant transitions between the states. The condensate is loaded into the optical lattice. We invoke the tight-binding approximation and examine the interplay of spatial and internal dynamics of the mixture. We show that internal dynamics qualitatively depends on the intra-component interaction strength and the phase configuration of the initial state. We focus attention on two intriguing phenomena occurring at certain values of the parameters. The first phenomenon is the spontaneous synchronization of Rabi oscillations running inside neighboring lattice sites. The other one is demixing of the condensate with formation of immiscible solitons at sufficiently strong nonlinearity. Demixing is preceded by the transient regime with highly irregular behavior of the mixture. 相似文献
8.
The dressing of atomic states in a strong laser field modifies the structure of the incoherently scattered fraction of the laser intensity, which is described to a good approximation by the Mollow spectrum. The incoherent spectrum is generated by the fluctuations of the atomic dipole moment about its expectation value, and the positions of the peaks are approximately given by the energy differences between the dressed atomic energy levels. In this paper, we investigate radiative corrections received by the dressed states. Our calculations are motivated by the quest to understand in detail the interplay of a bound electron dressed by the highly populated laser mode and its interaction with the vacuum modes. Alternatively, this may be seen as an electron experiencing modified stimulated and spontaneous radiative corrections in a vacuum tailored by the laser field. We obtain dressed self-energy shifts that depend on the Rabi flopping frequency (and in turn on the laser intensity) and on the detuning of the laser field relative to the atomic resonance frequency. We find that the dressed radiative corrections differ in a nontrivial manner from the radiative shifts of the ‘bare’ atomic states. 相似文献
9.
Through picture of dressed states, this paper investigates
the spontaneous emission spectrum from a microwave-driven
three-level atom embedded in a double-band photonic crystals. The
physical dynamics of the phase dependent phenomenon is analysed by
comparing two models `upper level coupling' and `lower level
coupling'. When the phase is changed from 0 to $\pi$, the variety of
spontaneous emission spectra from either of the two models are
inverse to each other, in which the relative height and width of
peaks are determined by the density of states in photonic crystals. 相似文献
10.
A. Lindner H. Freese G. Quehl D. Reiß K. Schiller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):99-112
The time evolution of a damped two-level atom coupled to a damped field mode at resonance is calculated analytically as well
as numerically in the basis of dressed states. We study the dynamics of the density matrix and of observables, e.g. the number of field quanta. For the initial states we consider the field to be in a Fock or Glauber state and the atom in
the ground or excited state. We show the significant influence of the damping on the well-known phenomena of this model, e.g. collapse and revival.
Received 22 January 2001 and Received in final form 16 May 2001 相似文献
11.
基于原子与腔场共振相互作用及原子-场缀饰态,讨论了驻波腔场中两能级原子与场耦合强度相关时的原子质心的量子化平移运动对原子内态布居间的相互影响。结果表明原子平移运动敏感地依赖于原子的内态布居。特别地,当原子处于两内态等权重同位相迭加态时,平移运动呈现出很稳定的特征。 相似文献
12.
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14.
Prediction of kinetic demixing in a quaternary mixed oxide (A,B, C)O in an oxygen potential gradient
Kinetic demixing in quaternary mixed oxides has not been investigated previously, either theoretically or experimentally. In this theoretical study, we derive simple and exact analytical expressions that describe the steady-state cation concentration profiles resulting from kinetic demixing in mixed oxides of the (A, B, C)O type. The concentration profiles are expressed in terms of cation-vacancy exchange frequency ratios. We assume a random distribution of cations and make use of the Moleko-Allnatt exact sum-rule expression relating the phenomenological coefficients in the ternary random alloy to the vacancy mechanism operative. We employ Monte Carlo simulation of kinetic demixing to verify the result of the analysis. We discuss how kinetic demixing profiles can be processed to obtain atom-vacancy exchange frequency ratios. We also discuss how atom-vacancy exchange frequencies themselves might be obtained from available diffusivities in the quaternary oxide. 相似文献
15.
Gorshkov AV Manmana SR Chen G Ye J Demler E Lukin MD Rey AM 《Physical review letters》2011,107(11):115301
By selecting two dressed rotational states of ultracold polar molecules in an optical lattice, we obtain a highly tunable generalization of the t-J model, which we refer to as the t-J-V-W model. In addition to XXZ spin exchange, the model features density-density interactions and density-spin interactions; all interactions are dipolar. We show that full control of all interaction parameters in both magnitude and sign can be achieved independently of each other and of the tunneling. As a first step towards demonstrating the potential of the system, we apply the density matrix renormalization group method to obtain the 1D phase diagram of the simplest experimentally realizable case. Specifically, we show that the tunability and the long-range nature of the interactions in the t-J-V-W model enable enhanced superfluidity. Finally, we show that Bloch oscillations in a tilted lattice can be used to probe the phase diagram experimentally. 相似文献
16.
在偶极近似下,研究了激光场中双原子分子的修饰态(dressed state),讨论了修饰态之间的自发辐射;与没有激光时相应过程比较,结果表明激光影响下荧光呈多重结构。 相似文献
17.
In this Letter we study dressed bound states in Fermi-Bose mixtures near broad interspecies resonances, and implications on many-body correlations. We present the evidence for a first order phase transition between a mixture of Fermi gas and condensate, and a fully paired mixture where extended fermionic molecules occupy a single pairing channel instead of forming a molecular Fermi surface. We further investigate the effect of Fermi surface dynamics and pair fluctuations and discuss the validity of our results. 相似文献
18.
We present a unified model of shear-induced demixing and "mechanical" shear banding instabilities in polymeric and surfactant solutions, by combining a simple flow instability with a two-fluid approach to concentration fluctuations. Within this model, we calculate the "spinodal" limit of stability of initially homogeneous shear states to demixing/banding, and predict the selected length and time scales at which inhomogeneity first emerges after a shear start-up "quench" into the unstable region, finding qualitative agreement with experiment. Our analysis is the counterpart, for this driven phase transition, of the Cahn-Hilliard calculation for unsheared fluid-fluid demixing. 相似文献
19.
The final-state energy spectrum in the photoionization of an initially populated adiabatic dressed state is studied. For weak dressing interactions, Raman coupling between dressed states significantly alters the form of the spectrum. 相似文献
20.
We propose an efficient scheme to generate a macroscopical quantum superposition state with a cavity optomechanical system, which is composed of a quantum Rabi-Stark model coupling to a mechanical oscillator. In a low-energy subspace of the Rabi-Stark model, the dressed states and then the effective Hamiltonian of the system are given. Due to the coupling of the mechanical oscillator and the atom-cavity system, if the initial state of the atom-cavity system is one of the dressed states, the mechanical oscillator will evolve into a corresponding coherent state. Thus, if the initial state of the atom-cavity system is a superposition of two dressed states, a coherent state superposition of the mechanical oscillator can be generated. The quantum coherence and their distinguishable properties of the two coherent states are exhibited by Wigner distribution. We show that the Stark term can enhance significantly the feasibility and quantum coherence of the generated macroscopic quantum superposition state of the oscillator. 相似文献