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Updated: Jun 3, 2026

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
Published on: August 2, 2019
Complex critical exponents for percolation transitions in Josephson-junction arrays, antiferromagnets, and
Rafael M Fernandes1, Jörg Schmalian
1Ames Laboratory, Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
Abstract:
We show that the critical behavior of the XY quantum-rotor model undergoing a percolation transition is dramatically affected by its topological Berry phase 2π ρ. In particular, for irrational ρ, its low-energy excitations emerge as spinless fermions with fractal spectrum. As a result, critical properties not captured by the usual Ginzburg-Landau-Wilson description of phase transitions arise, such as complex critical exponents, log-periodic oscillations and dynamically broken scale invariance.
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