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1.
Several years ago, in quantum mechanics, Davies proposed a method to calculate particle’s traveling time with the phase difference of wave function. The method is convenient for calculating the sojourn time inside a potential step and the tunneling time through a potential hill. We extend Davies’ non-relativistic calculation to relativistic quantum mechanics, with and without particle-antiparticle creation, using Klein–Gordon equation and Dirac Equation, for different forms of energy-momentum relation. The extension is successful only when the particle and antiparticle creation/annihilation effect is negligible. 相似文献
2.
We explore the tunneling behavior of a quantum particle on a finite graph in the presence of an asymptotically large potential
with two or three potential wells. The behavior of the particle is primarily governed by the local spectral symmetry of the
graph around the wells. In the case of two wells the behavior is stable in the sense that it can be predicted from a sufficiently
large neighborhood of the wells. However in the case of three wells we are able to exhibit examples where the tunneling behavior
can be changed significantly by perturbing the graph arbitrarily far from the wells. 相似文献
3.
We have established a set of balance equations to demonstrate the hot electron effect in the quantum tunneling processes by using the well-known effective tunneling Hamiltonian model. The high field effects both in reservoirs and in barrier region are discussed in detail. We also find a new field-dependent characteristic time due to nonequilibrium of reservoirs (the left-and right-sides of the barrier region) in the double-barrier structure. 相似文献
4.
We propose a quantum tweezer for extracting a desired number of neutral atoms from a reservoir. A trapped Bose-Einstein condensate is used as the reservoir, taking advantage of its coherent nature, which can guarantee a constant outcome. The tweezer is an attractive quantum dot, which may be generated by red-detuned laser light. By moving at certain speeds, the dot can extract a desired number of atoms from the condensate through Landau-Zener tunneling. The feasibility of our quantum tweezer is demonstrated through realistic and extensive model calculations. 相似文献
5.
《Superlattices and Microstructures》1995,17(2):197-200
A novel planar electron waveguide coupler is proposed as an electronic switch. The structure consists of two quantum wires interconnected by a dual branch coupling scheme which is assumed to be controlled by an electrostatic potential. Switching is provided by tuning the phase relations between the different scattered waves by the two coupling branch lines. Assuming ballistic transport, the analysis is conducted by solving the time independent two-dimensional Schrödinger equation in order to derive the conductance characteristics. At a resonant energy of 25 meV and for a waveguide width of 27.4 nm, over 90% of the electron wave has been transferred with a half picosecond time response. 相似文献
6.
Folman R Kruger P Cassettari D Hessmo B Maier T Schmiedmayer J 《Physical review letters》2000,84(20):4749-4752
Atoms can be trapped and guided using nanofabricated wires on surfaces, achieving the scales required by quantum information proposals. These atom chips form the basis for robust and widespread applications of cold atoms ranging from atom optics to fundamental questions in mesoscopic physics, and possibly quantum information systems. 相似文献
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8.
A quantum black hole has been presented by Kenmoku et al. (1998), and its surface gravity is divergent. We find that its tunneling probability is essentially different from Boltzmann distribution. It is interesting that two peaks appears in the spectrum when the black hole mass decreases close to Planck mass, which is different from black body radiation.
PACS: 04.70.Dy 相似文献
9.
Zhao-Xian Yu Zhi-Yong Jiao Fu-Ping Liu 《International Journal of Theoretical Physics》2008,47(4):1092-1094
We have studied quantum tunneling in an order-parameter-preserving antiferromagnet with the help of Holstein-Primakoff transformation.
It is found that, when the system being prepared in a coherent state, there exist the quantum tunneling between lattices k and k+1, k and k−1, respectively. In particular, when the lattice is infinitely long and the spin excitations are in the long-wavelength limit,
quantum tunneling disappear between lattices k and k+1, and that k and k−1, in this case the magnetic soliton appears. 相似文献
10.
11.
The adsorption of rare gases on metal surfaces serves as the paradigm of weak adsorption where it is typically assumed that the adsorbate occupies maximally coordinated hollow sites. Density-functional theory calculations using the full-potential linearized augmented plane wave method for Xe adatoms on Mg(0001), Al(111), Ti(0001), Cu(111), Pd(111), and Pt(111), show, however, that Xe prefers low coordination on-top sites in all cases. We identify the importance of polarization and a site-dependent Pauli repulsion in actuating the site preference and the principle nature of the rare-gas atom-metal surface interaction. 相似文献
12.
LI Hui-Ling YANG Shu-Zheng QI De-Jiang 《理论物理通讯》2006,46(6):991-994
Based on particles in a dynamical geometry, extending the Parikh 's method of quantum tunneling, radiation, we deeply investigate the quantum tunneling radiation of Kerr-NUT bhck hole. When self-gravitating action, energy conservation, and angular momentum conservation are taken into account, the emission rate of the particle on the event horizon is related to the change of Bekenstein-Hawking entropy and the emission spectrum is not precisely thermal, but is consistent with an underlying unitary theory. 相似文献
13.
为捕获于光阱中的冷原子拍照,需要配合使用一个快速“闪光”,将它们照亮。而不幸的是,闪光会使冷原子热起来,并将它们从光阱逐出。两个新实验绕过了这个问题,通过使用一组激光光束,在冷却原子的同时,成功地拍摄到一个个冷原子的空间占位。这类量子气显微镜用于成像费米冷原子,尚属首次。新实验为使用冷原子模拟强关联系统中的电子提供了机会,例如模拟高温超导体和超巨磁电阻材料。在过去的几年里,研究人员已经对光学晶格中的玻色原子实现了量子气显微镜成像。使用光频饴(光学粘胶)和其他技术, 在成像过程中保持原子气冷却。与玻色原子相比,费米原子不容易“上像”。这主要是因为,作为费米原子,如锂-6和钾-40,它们更难被冷却。但现在,两个研究组已经成功地摄取了冷费米原子的图像:Zwierlein和他在麻省理工学院的同事展示了他们针对钾原子气的成像技术;而哈佛大学的Greiner等则是完成了对锂原子的成像。 相似文献
14.
LI Hui-Ling YANG Shu-Zheng QI De-Jiang 《理论物理通讯》2006,46(12)
Based on particles in a dynamical geometry, extending the Parikh‘s method of quantum tunneling radiation,we deeply investigate the quantum tunneling radiation of Kerr-NUT black hole. When self-gravitating action, energyconservation, and angular momentum conservation are taken into account, the emission rate of the particle on the event horizon is related to the change of Bekenstein-Hawking entropy and the emission spectrum is not precisely thermal, but is consistent with an underlying unitary theory. 相似文献
15.
Ishikawa K Yamamoto T Takagi Y 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2006,179(2):234-240
We measured the spin relaxation of polarized xenon atoms dissolved in deuterated ethanol. Surface relaxation was suppressed by coating the cell walls with deuterated eicosane. From the dependence of the decay rate on temperature and static magnetic field, we obtained the correlation time of random fluctuations of the local field at the liquid-solid interface. By varying the cell volume, the wall coating, and the surface area of the eicosane, we measured the contribution of the spin-rotation interaction to the relaxation. The use of both deuterated molecules enables us to distinguish surface relaxation from the magnetic dipole-dipole and spin-rotation interactions in solution. 相似文献
16.
We present a complete scheme for quantum information processing using the unique features of alkaline-earth-metal atoms. We show how two completely independent lattices can be formed for the 1S0 and 3P0 states, with one used as a storage lattice for qubits encoded on the nuclear spin, and the other as a transport lattice to move qubits and perform gate operations. We discuss how the 3P2 level can be used for addressing of individual qubits, and how collisional losses from metastable states can be used to perform gates via a lossy blockade mechanism. 相似文献
17.
By measurements of the electron energy distribution function in a Xe afterglow plasma, the rate constants of the binary ionizing collisions between metastable Xe atoms were determined. The value of β22 = (7.3 ± 1) × 10?10cm3s?1 satisfactorily agrees with the value for a van der Waals capture. 相似文献
18.
We investigate the coherent tunneling phenomenon of the laser-driven atomic ensembles confined in a well-separated double-well potential. By generalizing the Frohlich canonical transformation to adiabatically eliminate the light field variable, a BCS-like effective Hamiltonian is obtained to depict the residual interaction between the two atomic ensembles. The number of the tunneling collective low excitations and its relationship to the ratios gr/gl and Nr/Nl are given. 相似文献
19.
<正>We discuss the feasibility of realizing a cold atom space clock with counter-propagating cold atoms in microgravity.The design of the space clock is based on an atomic beam clock with Ramsey cavity,except that magneto-optical trap(MOT) is placed at each side.Cold atoms are launched simultaneously from the MOTs at both sides of the clock and they move at the counter-direction towards each other.The velocity of the launched atoms is precisely controlled to Ramsauer-Townsend resonance so that no additional collision frequency shift takes place.Such configuration can efficiently cancel the frequency shift resulting from cavity phase shift and increase the signal-to-noise ratio(SNR). 相似文献
20.
N. V. Sidorkov 《Russian Physics Journal》1983,26(4):417-420