Bose-Spin Systems

Willi-Hans Steeb, Yorick Hardy

Ola Bratteli, Derek W. Robinson

Isaac Goldhirsch

An exact Bose expansion for general spin S is presented. It is a generalisation of a previously derived expansion for S= 1 / 2 . The analysis of the resulting Bose-Hilbert space yields a new understanding of existing Bose expansions and of the meaning of the spin-boson transformations in general. Bose expansions and of the meaning of the spin-boson transformations in general. The Bloch sum rule for spin systems is proven rigorously for any value of S and every temperature. It is argued that phase transitions in quantum spin systems can be regarded as generalised Bose condensation processes. Possible applications to quantum spin systems are mentioned.

G. J. Papadopoulos

The problem of obtaining the propagator of a spin-Bose system consisting of spins- 1/2 and several radiation modes in interaction is reduced to developing a bosonized Hamiltonian for the system from the propagator of which, by appropriate projection, the propagator relating to the original Hamiltonian is extracted. The analysis proceeds via functional integration involving the evaluation of two auxiliary propagators of Schrödinger equations whose Hamiltonians depend separately on radiation operators, and bosonized spin operators. These propagators are coupled through a complex field and the functional average of their product against a Gaussian measure of the field leads to the bosonized system’s propagator. The procedure is applied to the propagator for a single spin-Bose system which is obtained as a power series in the spin flipping energy. The analysis is also applied for an explicit evaluation in the case of a simplified spin-Bose Hamiltonian.

Chao Kong, Bin Yin, Jiaxin Wu +4 more

Abstract In this article, the modulation instability (MI) of open Bose–Bose mixtures with helicoidal spin–orbit coupling (SOC) was studied. Unlike previous spin–orbit (SO)-coupled Bose–Einstein condensate system with helicoidal gauge potential, the purpose of this article to study the input of the helicoidal SOC in the emergence of MI in open Bose–Bose mixtures by taking into account the Lee–Huang–Yang corrections to the coupled Gross–Pitaevskii equations. We present the detailed analyses of system parameters on the characteristics of MI and analytically conclude the parameter conditions for MI occurrence. Our results provide a potential way to manipulate the MI in the helicoidal SO-coupled open Bose–Bose mixtures.