Title

Infinite-Randomness Critical Point in the Two-Dimensional Disordered Contact Process

Presenter Information

Adam Farquhar

Department

Physics

Major

Physics

Research Advisor

Vojta, Thomas

Advisor's Department

Physics

Funding Source

NSF

Abstract

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 findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder. Our results are of importance beyond absorbing state transitions because, according to a strong-disorder renormalization group analysis, our transition belongs to the universality class of the two-dimensional random transverse-field Ising model.

Biography

Adam Farquhar is a sophomore pursuing his B.S. in Physics. He is involved with the Society of Physics Students and is serving as president of the organization this semester. In addition to conducting research, he also works at RadioShack.

Research Category

Sciences

Presentation Type

Poster Presentation

Document Type

Poster

Award

Sciences poster session, Second place

Location

Upper Atrium/Hallway

Presentation Date

08 Apr 2009, 9:00 am - 11:45 am

Comments

Joint project with Jason Mast

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Apr 8th, 9:00 AM Apr 8th, 11:45 AM

Infinite-Randomness Critical Point in the Two-Dimensional Disordered Contact Process

Upper Atrium/Hallway

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 findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder. Our results are of importance beyond absorbing state transitions because, according to a strong-disorder renormalization group analysis, our transition belongs to the universality class of the two-dimensional random transverse-field Ising model.