共查询到20条相似文献,搜索用时 312 毫秒
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以非线性Rosen-Zener隧穿理论为基础,用两分量Bose-Einstein凝聚体设计了非线性Ramsey干涉计.通过数值模拟实验在时间域上观察到了丰富的Ramsey干涉图样,凝聚体中原子间重要的非线性相互作用导致这些干涉图样明显不同于线性Ramsey干涉时的正弦型条纹.通过进一步对干涉图样作Fourier分析,发现干涉图样的基频能够精确反映系统的非线性和不对称性特征,从而为测量原子的相关性质提供了理论依据.
关键词:
Bose-Einstein凝聚
非线性Ramsey干涉
Rosen-Zener隧穿 相似文献
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基于非线性Rosen-Zener隧穿理论, 利用高斯型脉冲研究了双势阱玻色-爱因斯坦凝聚体的非线性Ramsey干涉. 通过数值模拟得到了丰富的非线性Ramsey干涉图样, 分别讨论了粒子间相互作用和高斯型脉冲的周期对干涉图样的影响. 通过哈密顿正则关系得到了干涉条纹的基频表达式, 并借助傅里叶变换对Ramsey干涉条纹的频率进行分析, 得到了干涉条纹的基频随粒子间相互作用及脉冲周期的变化关系. 比较数值和解析结果发现两者符合得很好.
关键词:
玻色-爱因斯坦凝聚
Ramsey干涉
高斯型脉冲 相似文献
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本文研究含有一个费米子杂质的玻色爱因斯坦凝聚体在光学微腔作用下的隧穿动力学性质,探讨腔对单粒子隧穿过程的影响。从光学微腔与双阱中玻色子-费米子混合凝聚体耦合体系的哈密顿量出发,推导出与光学腔耦合强度有关的粒子隧穿基态能级差的解析表达式以及相对粒子数差的期望值。研究结果表明:光学腔与原子的耦合强度能够影响优先隧穿的粒子种类以及粒子隧穿的阶梯图形。 相似文献
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研究了玻色-费米超流混合体系中的相互作用调制隧穿动力学特性,其中玻色子位于对称双势阱中,费米子位于对称双势阱中心的简谐势阱中.采用双模近似方法得到描述双势阱玻色-爱因斯坦凝聚的动力学特性方程组,并将其与简谐势阱中分子玻色-爱因斯坦凝聚的Gross-Pitaevskii方程进行耦合.通过对不同参数下玻色-费米混合体系中的隧穿现象进行数值研究,发现简谐势阱中费米子与双势阱中玻色子的相互作用使双势阱玻色-爱因斯坦凝聚的隧穿动力学特性更加丰富.不但驱使双势阱中玻色-爱因斯坦凝聚从类约瑟夫森振荡转变为宏观量子自囚禁,而且宏观量子自囚禁表现为三种不同的形式:相位与时间呈负相关并随时间单调减小的自囚禁、相位随时间演化有界的自囚禁以及相位与时间呈正相关并随时间单调增大的自囚禁. 相似文献
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The nonlinear Ramsey interferometry of Fermi superfluid gases in a double-well potential is investigated in this paper. We found that the frequency of the Ramsey fringes exactly reflects the strength of nonlinearity, or the scattering length of the Fermi superfluid gases. The cases of sudden limit, the adiabatic limit and the general case are studied. The analytical result is in good agreement with the numerical ones. The adiabatic condition is proposed. In general situation, the zero-frequency point emerge. Finally the possible applications of the theory are discussed. 相似文献
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D. Bambusi 《Physics letters. A》2008,372(12):2039-2042
We study numerically the dynamics of a chain of particles subjected to an on site restoring nonlinear force and a first neighbor harmonic coupling. We excite the first linear mode and investigate the distribution of the average harmonic energies at metastable regime, in the spirit of Fermi Pasta Ulam experiment. The limit distribution turns out to strongly depend on the boundary conditions. A theoretical discussion of the phenomenon is also given. 相似文献
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We show that both DC and AC Josephson effects with superfluid Fermi atoms in the BCS-BEC crossover can be described at zero temperature by a nonlinear Schrodinger equation (NLSE). By comparing our NLSE with mean-field extended BCS calculations, we find that the NLSE is reliable in the AAN side of the crossover up to the unitarity limit. The NLSE can be used for weakly-linked atomic superfluids also in the BCS side of the crossover by taking the tunneling energy as a phenomenological parameter. 相似文献
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We investigate a normal-metal-superconductor (point) contact in the limit where the number of conducting channels in the metallic
wire is reduced to few channels. As the effective Fermi energy drops below the gap energy, a conducting band with a width
twice the Fermi energy is formed. Depending on the mode of operation, the conduction band can be further squeezed, leading
to various nonlinear effects in the current-voltage characteristics such as current saturation, a N-shaped negative differential
resistance, bistability, and hysteresis.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 7, 572–577 (10 October 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
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Nascimbène S Navon N Pilati S Chevy F Giorgini S Georges A Salomon C 《Physical review letters》2011,106(21):215303
We measure the magnetic susceptibility of a Fermi gas with tunable interactions in the low-temperature limit and compare it to quantum Monte Carlo calculations. Experiment and theory are in excellent agreement and fully compatible with the Landau theory of Fermi liquids. We show that these measurements shed new light on the nature of the excitations of the normal phase of a strongly interacting Fermi gas. 相似文献
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Michael K.-H. Kiessling 《Communications in Mathematical Physics》2002,226(3):607-626
In the semi-classical limit the relativistic quantum mechanics of a stationary beam of counter-streaming (negatively charged)
electrons and one species of positively charged ions is described by a nonlinear system of finite-temperature Thomas–Fermi
equations. In the high temperature/low density limit these Thomas–Fermi equations reduce to the (semi-)conformal system of
Bennett equations discussed earlier by Lebowitz and the author. With the help of a sharp isoperimetric inequality it is shown
that any hypothetical particle density function which is not radially symmetric about and decreasing away from the beam's
axis would violate the virial theorem. Hence, all beams have the symmetry of the circular cylinder.
Received: 8 December 2000 / Accepted: 14 December 2001 相似文献
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We calculate the oscillation frequencies of trapped Fermi condensate with particular emphasis on the equation of state of the interacting Fermi system. We confirm Stringari's finding that the frequencies are independent of the interaction in the unitary limit, and we extend the theory away from that limit, where the interaction does affect the frequencies of the compressional modes only. 相似文献
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E. A. Kuznetsov 《JETP Letters》2017,105(2):125-129
We give a qualitative conceptual explanation of the Fermi–Pasta–Ulam (FPU) like recurrence in the onedimensional focusing nonlinear Schrodinger equation (NLSE). The recurrence can be considered as a result of the nonlinear development of the modulation instability. All known exact localized solitary wave solutions describing propagation on the background of the modulationally unstable condensate show the recurrence to the condensate state after its interaction with solitons. The condensate state locally recovers its original form with the same amplitude but a different phase after soliton leave its initial region. Based on the integrability of the NLSE, we demonstrate that the FPU recurrence takes place not only for condensate, but also for a more general solution in the form of the cnoidal wave. This solution is periodic in space and can be represented as a solitonic lattice. That lattice reduces to isolated soliton solution in the limit of large distance between solitons. The lattice transforms into the condensate in the opposite limit of dense soliton packing. The cnoidal wave is also modulationally unstable due to soliton overlapping. The recurrence happens at the nonlinear stage of the modulation instability. Due to generic nature of the underlying mathematical model, the proposed concept can be applied across disciplines and nonlinear systems, ranging from optical communications to hydrodynamics. 相似文献