Speaker
Description
We study disorder-dominated quantum models, including Ising-like random-field systems and equilibrium pinned elastic-manifold problems, near their zero-temperature critical regimes. We provide an explicit field-theoretic calculation supporting the fluctuationless fixed point scenario, in which the infrared critical fixed point is classical and quantum fluctuations enter through a dangerously irrelevant temperature-like scaling variable. This establishes a close correspondence with classical random-field models, whose critical dynamics is commonly formulated in terms of Langevin relaxation and is dominated by activated processes over barriers that grow as a positive power of the length scale.
We derive the resulting extremely slow, activated dynamical scaling from the interplay between disorder and quantum fluctuations, and connect this mechanism to the renormalization-group flow of the dynamical kernel and of the longest relaxation time. In the quantum problem, the activated form of the scaling should be interpreted as arising from tunneling between competing configurations, rather than from thermal activation over effective barriers in configuration space. Related mechanisms may also be relevant at other disorder-dominated quantum critical points, including the superfluid-Bose-glass transition in disordered bosons, disorder controlled transitions of relativistic semimetals, such as the ballistic semimetal to diffusive metal transition, and strongly disordered quantum magnets in which disorder cumulants control the infrared scaling.
| Affiliation | Institute of Physics, Zagreb |
|---|---|
| Career status | Senior |