2 research outputs found
Dissipative quantum disordered models
This article reviews recent studies of mean-field and one dimensional quantum
disordered spin systems coupled to different types of dissipative environments.
The main issues discussed are: (i) The real-time dynamics in the glassy phase
and how they compare to the behaviour of the same models in their classical
limit. (ii) The phase transition separating the ordered -- glassy -- phase from
the disordered phase that, for some long-range interactions, is of second order
at high temperatures and of first order close to the quantum critical point
(similarly to what has been observed in random dipolar magnets). (iii) The
static properties of the Griffiths phase in random Ising chains. (iv) The
dependence of all these properties on the environment. The analytic and numeric
techniques used to derive these results are briefly mentioned.Comment: Contribution to the 12th International Conference on Recent Progress
in Many-Body Theories, Santa Fe, New Mexico, USA, August 2004; 10 pages no
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Effects of dissipation on disordered quantum spin models
We study the effects of the coupling to an Ohmic quantum reservoir on the
static and dynamical properties of a family of disordered SU(2) spin models in
a transverse magnetic field using a method of direct spin summation. The
tendency to form a glassy phase increases with the strength of the coupling of
the system to the environment. We study the influence of the environment on the
features of the phase diagram of the various models as well as the stability of
the possible phases.Comment: 24 pages, 8 fig