1,127 research outputs found
Non-cyclic Geometric Phase due to Spatial Evolution in a Neutron Interferometer
We present a split-beam neutron interferometric experiment to test the
non-cyclic geometric phase tied to the spatial evolution of the system: the
subjacent two-dimensional Hilbert space is spanned by the two possible paths in
the interferometer and the evolution of the state is controlled by phase
shifters and absorbers. A related experiment was reported previously by
Hasegawa et al. [Phys. Rev. A 53, 2486 (1996)] to verify the cyclic spatial
geometric phase. The interpretation of this experiment, namely to ascribe a
geometric phase to this particular state evolution, has met severe criticism
from Wagh [Phys. Rev. A 59, 1715 (1999)]. The extension to a non-cyclic
evolution manifests the correctness of the interpretation of the previous
experiment by means of an explicit calculation of the non-cyclic geometric
phase in terms of paths on the Bloch-sphere.Comment: 4 pages, revtex
Quasi-Lagrangian Systems of Newton Equations
Systems of Newton equations of the form
with an integral of motion quadratic in velocities are studied. These equations
generalize the potential case (when A=I, the identity matrix) and they admit a
curious quasi-Lagrangian formulation which differs from the standard Lagrange
equations by the plus sign between terms. A theory of such quasi-Lagrangian
Newton (qLN) systems having two functionally independent integrals of motion is
developed with focus on two-dimensional systems. Such systems admit a
bi-Hamiltonian formulation and are proved to be completely integrable by
embedding into five-dimensional integrable systems. They are characterized by a
linear, second-order PDE which we call the fundamental equation. Fundamental
equations are classified through linear pencils of matrices associated with qLN
systems. The theory is illustrated by two classes of systems: separable
potential systems and driven systems. New separation variables for driven
systems are found. These variables are based on sets of non-confocal conics. An
effective criterion for existence of a qLN formulation of a given system is
formulated and applied to dynamical systems of the Henon-Heiles type.Comment: 50 pages including 9 figures. Uses epsfig package. To appear in J.
Math. Phy
Dynamics of the Tippe Top -- properties of numerical solutions versus the dynamical equations
We study the relationship between numerical solutions for inverting Tippe Top
and the structure of the dynamical equations. The numerical solutions confirm
oscillatory behaviour of the inclination angle for the symmetry
axis of the Tippe Top. They also reveal further fine features of the dynamics
of inverting solutions defining the time of inversion. These features are
partially understood on the basis of the underlying dynamical equations
Magnetic phase diagram of CePt3B1-xSix
We present a study of the main bulk properties (susceptibility,
magnetization, resistivity and specific heat) of CePt_3B_(1-x)Si-x, an alloying
system that crystallizes in a noncentrosymmetric lattice, and derive the
magnetic phase diagram. The materials at the end point of the alloying series
have previously been studied, with CePt_3B established as a material with two
different magnetic phases at low temperatures (antiferromagnetic below T_N =
7.8 K, weakly ferromagnetic below T_C ~ 5 K), while CePt3Si is a heavy fermion
superconductor (T_c = 0.75 K) coexisting with antiferromagnetism (T_N = 2.2 K).
From our experiments we conclude that the magnetic phase diagram is divided
into two regions. In the region of low Si content (up to x ~ 0.7) the material
properties resemble those of CePt3B. Upon increasing the Si concentration
further the magnetic ground state continuously transforms into that of CePt3Si.
In essence, we argue that CePt_3B can be understood as a low pressure variant
of CePt3Si.Comment: 7pages, 9figure
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