共查询到20条相似文献,搜索用时 15 毫秒
1.
B.Mirza M.Mohadesi 《理论物理通讯》2004,42(5):664-668
We study the Dirac and the Klein-Gordon oscillators in a noncommutative space. It is shown that the Klein-Gordon oscillator in a noncommutative space has a similar behaviour to the dynamics of a particle in a commutative space and in a constant magnetic field. The Dirac oscillator in a noncommutative space has a similar equation to the equation of motion for a relativistic fermion in a commutative space and in a magnetic field, however a new exotic term appears, which implies that a charged fermion in a noncommutative space has an electric dipole moment. 相似文献
2.
We give a definition of a universal entangling machine that entangles a system in an unknown state to a specially prepared ancilla. We describe explicitly such a machine for one qubit; i.e., we show how a qubit in an a priori unknown state can be entangled to a four-level ancilla by means of a unitary transformation. As a result, a fixed state-independent amount of entanglement is generated in exchange for a fixed degradation of qubit state fidelity. 相似文献
3.
We propose a new way to generate an observable geometric phase by means of a completely incoherent phenomenon. We show how to imprint a geometric phase to a system by adiabatically manipulating the environment with which it interacts. As a specific scheme, we analyze a multilevel atom interacting with a broadband squeezed vacuum bosonic bath. As the squeezing parameters are smoothly changed in time along a closed loop, the ground state of the system acquires a geometric phase. We also propose a scheme to measure such a geometric phase by means of a suitable polarization detection. 相似文献
4.
《Journal of Geometry and Physics》2001,40(2):176-200
The notion of a generalized Lie bialgebroid (a generalization of the notion of a Lie bialgebroid) is introduced in such a way that a Jacobi manifold has associated a canonical generalized Lie bialgebroid. As a kind of converse, we prove that a Jacobi structure can be defined on the base space of a generalized Lie bialgebroid. We also show that it is possible to construct a Lie bialgebroid from a generalized Lie bialgebroid and, as a consequence, we deduce a duality theorem. Finally, some special classes of generalized Lie bialgebroids are considered: triangular generalized Lie bialgebroids and generalized Lie bialgebras. 相似文献
5.
The instability of a period-1 spiral wave resulting in a period-2 spiral wave with a line defect is investigated for the first time in a laboratory system. At the very onset the transition proceeds by an emergence of a spiraling line defect, "breathing" intermittently while retaining its symmetry of a period-1 spiral wave. With a further change in a control parameter, the line defect undergoes a meandering transition producing a compound tip trajectory, following a dynamic shape transition. The observed transitions have a strong analogy to the phase synchronization transition of two coupled nonlinear oscillators and the meandering transition of a period-1 spiral wave. 相似文献
6.
F. J. Elmer 《Zeitschrift für Physik B Condensed Matter》1987,68(1):105-114
The pattern formation process in a transversal circular pumped ferromagnetic resonance system above the second order Suhl instability is studied in a model which is a spatially one-dimensional partial integro-differential equation of motion with a periodic boundary condition. Instead of a bifurcation into a spatially periodic pattern, the homogeneous state bifurcates into a solution with a fast spatial oscillation which is modulated by a slow oscillation. Only for higher pumpfields a second bifurcation into a simple periodic state occurs.This work was performed within the program of the Sonderforschungsbereich 65 Darmstadt-Frankfurt 相似文献
7.
《Physics letters. A》1996,223(4):267-272
The effects of a magnetic field on a modulated phase are studied. A modulated phase is found to have two critical fields H1 and H2. For a large enough magnetic field, H1 and H2 can be approximated by a linear law. As a result, the minimum magnetic field needed to destroy a modulated phase is a constant. The minimum magnetic field also greatly depends on the order of a commensurate phase. A very high order commensurate phase and an incommensurate phase cannot survive a magnetic field. The behaviour of a magnetoelastic chain in a magnetic field can be described by a harmless devil's staircase. The inverse temperature is found to play a role similar to that of a special magnetic field. The deeper physics underlying these new phenomena is the breaking of the left-right symmetry of a phase diagram. As a result a controllable path to a modulated phase is found. 相似文献
8.
Ben-Kish A DeMarco B Meyer V Rowe M Britton J Itano WM Jelenković BM Langer C Leibfried D Rosenband T Wineland DJ 《Physical review letters》2003,90(3):037902
Using a single, harmonically trapped 9Be(+) ion, we experimentally demonstrate a technique for generation of arbitrary states of a two-level particle confined by a harmonic potential. Rather than engineering a single Hamiltonian that evolves the system to a desired final state, we implement a technique that applies a sequence of simple operations to synthesize the state. 相似文献
9.
Kazuya Hayata 《Optical Review》1997,4(2):303-304
It is shown that, at a critical point where the effective refractive index of a mode coincides with the bulk index of a cladding region, optical waveguide modes exhibiting a lognormal feature are supportable for a hyperlongrange refractive-index profile. As a typical example of waveguides that support lognormal modes a parabolic-index core surrounded by a depressed-index cladding is presented. 相似文献
10.
Ricci M Sciarrino F Cerf NJ Filip R Fiurásek J De Martini F 《Physical review letters》2005,95(9):090504
An application of quantum cloning to optimally interface a quantum system with a classical observer is presented; in particular, we describe a procedure to perform a minimal disturbance measurement on a single qubit by adopting a 1-->2 cloning machine followed by a generalized measurement on a single clone and the anticlone or on the two clones. Such a scheme can be applied to enhance the transmission fidelity over a lossy quantum channel. 相似文献
11.
We define the notion of a pendulum on a surface of constant curvature and study the motion of a mass at a fixed distance from
a pivot. We consider some special cases: first a pivot that moves with constant speed along a geodesic, and then a pivot that
undergoes acceleration along a fixed geodesic.
相似文献
12.
In Hele-Shaw flows, a boundary of a viscous fluid develops unstable fingering patterns. At vanishing surface tension, fingers
evolve to cusp-like singularities preventing a smooth flow. We show that the Hele-Shaw problem admits a weak solution where
a singularity triggers viscous shocks. Shocks form a growing, branching tree of a line distribution of vorticity where pressure
has a finite discontinuity. A condition that the flow remains curl-free at a macroscale uniquely determines the shock graph
structure. We present a self-similar solution describing shocks emerging from a generic (2, 3)-cusp singularity—an elementary
branching event of a branching shock graph. 相似文献
13.
《Waves in Random and Complex Media》2013,23(1):156-178
This paper is devoted to scattering from a canonical object above a sea-like one-dimensional rough surface (two-dimensional problem). Such a problem involves a high number of unknowns and cannot be solved easily with a Method of Moments by using a direct LU inversion. Thus, a recently developed fast numerical method called Extended-PILE combined with FB-SA is used. First, a parametrization is proposed for the FB-SA by considering the sea surface only. Then, the convergence of E-PILE+FB-SA is tested for the scattering from a cylinder, a plate and a cross located above a rough surface obeying a Gaussian process with the Elfouhaily et al. spectrum. After generating several surface realizations, a Monte Carlo process is applied on the scattered fields in order to discuss on the Normalized Radar Cross-Section (NRCS) for a maritime application at microwave frequencies. Eventually, the study focuses on the case of low grazing incidence. 相似文献
14.
This study proposes a beam shaper for converting a circle beam profile generated with a Gaussian intensity distribution by an 808 nm diode laser into a line beam profile for silicon surface treatment applications. To produce a hand-held and low-cost device with a large spot-size laser, this study uses a portable optical system consisting of a diode laser source, a collimator, a cylindrical lens, and a plano-convex lens to generate an approximately 40 × 3:5mm2 line beam profile at a working distance of 200 mm. The silicon surface treated by the line-shaped laser beam has significantly reduced reflectance spectra. The proposed system is also suitable for the surface cleaning of materials. 相似文献
15.
A non-abelian phase space, or a phase space of a Lie algebra, is a generalization of the usual (abelian) phase space of a vector space. It corresponds to a para-Kähler structure in geometry. Its structure can be interpreted in terms of left-symmetric algebras. In particular, a solution of an algebraic equation in a left-symmetric algebra which is an analogue of classical Yang–Baxter equation in a Lie algebra can induce a phase space. In this paper, we find that such phase spaces have a symplectically isomorphic property. We also give all such phase spaces in dimension 4 and some examples in dimension 6. These examples can be a guide for a further development. 相似文献
16.
G. Brida M. Genovese M. G. A. Paris F. Piacentini E. Predazzi E. Vallauri 《Optics and Spectroscopy》2007,102(1):90-97
The propagation of pulses of the pump and its second harmonic in a quadratically nonlinear medium whose linear properties are characterized by a negative refractive index at the pump frequency and by a positive refractive index at the harmonic frequency is considered theoretically. In the case of a low intensity of the interacting waves, the pump and second-harmonic pulses propagate in the opposite directions, but sufficiently powerful pulses can form a simulton—a solitary two-frequency wave propagating in a certain direction as a single whole. Solutions to a set of equations are found which describe the steady-state propagation of a solitary wave and of a nonlinear periodic (cnoidal) wave. 相似文献
17.
The quantum mechanical formulation of the screening of a point charge by surface plasmons is extended to describe the coupling of a fluctuating atomic dipole with a metallic surface of planar, spherical or cylindrical shape. This allows for the calculation of the nonretarded Van der Waals attraction of an atom by a solid surface in the three different geometries. Applications of the theoretical formulae are made to obtain numerical values of the dispersion energy by a spherical particle, a spherical pore, a thin film, a slot-like prore, a cylindrical fiber or a cylindrical pore. 相似文献
18.
A. A. Vikharev G. G. Denisov Vl. V. Kocharovsky S. V. Kuzikov V. V. Parshin N. Yu. Peskov A. N. Stepanov D. I. Sobolev M. Yu. Shmelev 《Radiophysics and Quantum Electronics》2007,50(10-11):786-793
We study, both numerically and experimentally, a microwave commutator (phase shifter), whose active element comprises a metal plane mirror with a semiconductor plate on it. Phase shifting of the reflected microwave beam is attained by creating a conducting layer in the semiconductor by a laser with quantum energy approximately equal to the forbidden band width. Using a disk of high-purity silicon and a titatnium-sapphire pulsed laser, we study experimentally a 180° phase shifter operated with a Gaussian wave beam at a frequency of 30 GHz. Efficient phase shifting of the wave beam over a time of several nanoseconds is shown at a low power level. 相似文献
19.
Deformation quantisation is applied to ordinary Quantum Mechanics by introducing the star product in a configuration space combining a Riemannian structure with a Poisson one. A Hilbert space compatible with such a configuration space is designed. The dynamics is expressed by a Hermitian Hamiltonian containing a scalar potential and a one-form potential. As a simple illustration, it is shown how a particular type of non-commutativity of the star product is interpretable as generating the Zeeman effect of ordinary Quantum Mechanics. 相似文献
20.
The distribution of axes of easy magnetization close to a homogeneous distribution is revealed in each half-thickness of a ribbon after annealing it in a helical magnetic field. The transition from magnetic reversal of a ribbon by the displacement of two domain walls formed near a middle plane of a ribbon to magnetic reversal of a ribbon by displacement of two domain walls formed near to the main surfaces of a ribbon is found out during each half-period of a magnetic reversal. 相似文献