TY - JOUR

T1 - Quantum criticality in Ising chains with random hyperuniform couplings

AU - Crowley, P. J.D.

AU - Laumann, C. R.

AU - Gopalakrishnan, S.

N1 - Publisher Copyright:
© 2019 American Physical Society.

PY - 2019/10/17

Y1 - 2019/10/17

N2 - We study quantum phase transitions in transverse-field Ising spin chains in which the couplings are random but hyperuniform, in the sense that their large-scale fluctuations are suppressed. We construct a one-parameter family of disorder models in which long-wavelength fluctuations are increasingly suppressed as a parameter α is tuned. For α=0, one recovers the familiar infinite-randomness critical point. For 0<α<1, we find a line of infinite-randomness critical points with continuously varying critical exponents; however, the Griffiths phases that flank the critical point at α=0 are absent at any α>0. When α>1, randomness is a dangerously irrelevant perturbation at the clean Ising critical point, leading to a state we call the critical Ising insulator. In this state, thermodynamics and equilibrium correlation functions behave as in the clean system. However, all finite-energy excitations are localized, thermal transport vanishes, and autocorrelation functions remain finite in the long-time limit. We characterize this line of hyperuniform critical points using a combination of perturbation theory, renormalization-group methods, and exact diagonalization.

AB - We study quantum phase transitions in transverse-field Ising spin chains in which the couplings are random but hyperuniform, in the sense that their large-scale fluctuations are suppressed. We construct a one-parameter family of disorder models in which long-wavelength fluctuations are increasingly suppressed as a parameter α is tuned. For α=0, one recovers the familiar infinite-randomness critical point. For 0<α<1, we find a line of infinite-randomness critical points with continuously varying critical exponents; however, the Griffiths phases that flank the critical point at α=0 are absent at any α>0. When α>1, randomness is a dangerously irrelevant perturbation at the clean Ising critical point, leading to a state we call the critical Ising insulator. In this state, thermodynamics and equilibrium correlation functions behave as in the clean system. However, all finite-energy excitations are localized, thermal transport vanishes, and autocorrelation functions remain finite in the long-time limit. We characterize this line of hyperuniform critical points using a combination of perturbation theory, renormalization-group methods, and exact diagonalization.

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U2 - 10.1103/PhysRevB.100.134206

DO - 10.1103/PhysRevB.100.134206

M3 - Article

AN - SCOPUS:85074542561

SN - 2469-9950

VL - 100

JO - Physical Review B

JF - Physical Review B

IS - 13

M1 - 134206

ER -