scholarly journals Excited states of quasi-one-dimensional hexagonal quantum antiferromagnets

2013 ◽  
Vol 87 (17) ◽  
Author(s):  
M. Merdan ◽  
Y. Xian
Keyword(s):  
Excited States ◽  
One Dimensional ◽  
Quantum Antiferromagnets

Dilution-induced order in quasi-one-dimensional quantum antiferromagnets

1991 ◽  
Vol 66 (18) ◽  
pp. 2384-2387 ◽  
Author(s):  
Eugene F. Shender ◽  
Steven A. Kivelson
Keyword(s):  
One Dimensional ◽  
Quantum Antiferromagnets

Theory of Photoinduced Phase Transitions: From Semiclassical to Quantum Aspects

2006 ◽  
Vol 112 ◽  
pp. 21-38
Author(s):  
Tetsuo Ogawa
Keyword(s):  
Phase Transitions ◽  
Excited States ◽  
Domain Walls ◽  
Particle Density ◽  
Structural Phase ◽  
Electron Hole ◽  
One Dimensional ◽  
First Order Phase Transition ◽  
New Material ◽  
First Order Phase

We review recent progress of theoretical studies for the photoinduced phase tran- sitions (PIPTs) to clarify what the PIPTs are. There are two types of the PIPTs: (a) global change via optically excited states and (b) new material phase creation in optically excited states. First, concerning (a), photoinduced structural phase transitions via excited electronic states are discussed using a minimal one-dimensional model composed of localized electrons and lattices. We show that the global structural change by photoexcitation only at a single site is possible under the adiabatic or diabatic approximation. This dynamics of the domain bound- aries (domain walls) is called the “photoinduced domino process,” which is the photoinduced nucleation in nonequilibrium first-order phase transition. Second, concerning (b), we discuss quantum orders of electron-hole (e-h) systems, which are optically excited states of insulators consisting of many electrons and holes in two bands. In particular, the “exciton Mott transi- tion,” i.e., the “from-insulator-to-metal” transition of the e-h systems as the particle density increases is introduced. We stress that this transition depends strongly on dimensionality of the system.

SEPARABILITY AND STABILITY OF SOLUTIONS OF THE 1-DIMENSIONAL NLSE WITH RESPECT TO EXTENSION INTO 2 AND 3 DIMENSIONS, AND TO INITIAL PERTURBATION BY WHITE NOISE

2001 ◽  
Vol 15 (10n11) ◽  
pp. 1668-1671
Author(s):  
WILLIAM P. REINHARDT ◽  
MARY ANN LEUNG ◽  
LINCOLN D. CARR
Keyword(s):  
White Noise ◽  
Excited States ◽  
Initial Perturbation ◽  
Einstein Condensate ◽  
One Dimensional ◽  
Bose Einstein Condensate ◽  
Variable Step ◽  
Direct Numerical Integration ◽  
Bose Einstein ◽  
Pseudo Spectral

Stationary states of the nonlinear Schrödinger equation (NLSE) found analytically in previous work are extended into 2 and 3 dimensions by the simplest possible ansatz: namely, it is assumed that the direct product of one dimensional solutions for each dimension will yield a stationary state. The solutions considered mimic the dynamics of a repulsive Bose-Einstein condensate (BEC) in a trap of high aspect ratio. This assumption of separability, as established by direct numerical integration of the NLSE via variable step 4th order Runge-Kutta using a pseudo spectral basis, is found to work well for both ground and excited states for box transverse confinement, and for either box or periodic boundary conditions along the longest trap axis. Addition of white noise at t = 0, followed by similar numerical propagation in either 2 or 3 dimensions, is found to lead to instability once the transverse confining dimension are greater than approximately 6 healing lengths. Such instabilites eventually manifest themselves as vortices fathered by the well known snake instability of the NLSE solitons in dimensionalities higher than 1. The dynamics of interacting solitons may become chaotic as the solitons themselves become unstable in the presence of noise.

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