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Full-Text Articles in Physical Sciences and Mathematics
Absorbing-State Phase Transitions On Percolating Lattices, Man Young Lee, Thomas Vojta
Absorbing-State Phase Transitions On Percolating Lattices, Man Young Lee, Thomas Vojta
Physics Faculty Research & Creative Works
We study nonequilibrium phase transitions of reaction-diffusion systems defined on randomly diluted lattices, focusing on the transition across the lattice percolation threshold. To develop a theory for this transition, we combine classical percolation theory with the properties of the supercritical nonequilibrium system on a finite-size cluster. In the case of the contact process, the interplay between geometric criticality due to percolation and dynamical fluctuations of the nonequilibrium system leads to a different universality class. The critical point is characterized by ultraslow activated dynamical scaling and accompanied by strong Griffiths singularities. To confirm the universality of this exotic scaling scenario we …
Infinite-Randomness Quantum Critical Points Induced By Dissipation, Thomas Vojta, Chetan Kotabage, Jose A. Hoyos
Infinite-Randomness Quantum Critical Points Induced By Dissipation, Thomas Vojta, Chetan Kotabage, Jose A. Hoyos
Physics Faculty Research & Creative Works
We develop a strong-disorder renormalization group to study quantum phase transitions with continuous O(N) symmetry order parameters under the influence of both quenched disorder and dissipation. For Ohmic dissipation, as realized in Hertz's theory of the itinerant antiferromagnetic transition or in the superconductor-metal transition in nanowires, we find the transition to be governed by an exotic infinite-randomness fixed point in the same universality class as the (dissipationless) random transverse-field Ising model. We determine the critical behavior and calculate key observables at the transition and in the associated quantum Griffiths phase. We also briefly discuss the cases of super-Ohmic and sub-Ohmic …
Infinite-Randomness Critical Point In The Two-Dimensional Disordered Contact Process, Thomas Vojta, A. Farquhar, J. Mast
Infinite-Randomness Critical Point In The Two-Dimensional Disordered Contact Process, Thomas Vojta, A. Farquhar, J. Mast
Physics Faculty Research & Creative Works
We study the nonequilibrium phase transition in the two-dimensional contact process on a randomly diluted lattice by means of large-scale Monte Carlo simulations for times up to 1010 and system sizes up to 8000×8000 sites. Our data provide strong evidence for the transition being controlled by an exotic infinite-randomness critical point with activated (exponential) dynamical scaling. We calculate the critical exponents of the transition and find them to be universal, i.e., independent of disorder strength. The Griffiths region between the clean and the dirty critical points exhibits power-law dynamical scaling with continuously varying exponents. We discuss the generality of our …