The main objective of this thesis is the development of geometrical methods for the investigation of critical phenomena. In particular, a novel approach based on the Uhlmann curvature is introduced for the investigation of non-equilibrium steady-state quantum phase transitions (NESS-QPTs). Equilibrium phase transitions fall invariably into two markedly non-overlapping categories: classical phase transitions and quantum phase transitions. NESS-QPTs offer a unique arena where such a distinction fades off. We propose a method to reveal and quantitatively assess the quantum character of such critical phenomena. We apply this tool to a paradigmatic class of lattice fermion systems with local reservoirs, characterised by Gaussian non-equilibrium steady states. The relations between the behaviour of the Uhlmann curvature, the divergence of the correlation length, the character of the criticality and the dissipative gap are demonstrated. We argue that this tool can shade light upon the nature of non equilibrium steady state criticality in particular with regard to the role played by quantum vs classical fluctuations.

GEOMETRY OF DISSIPATIVE PHASE TRANSITIONS.

GEOMETRY OF DISSIPATIVE PHASE TRANSITIONS

Carollo, Angelo

Abstract

The main objective of this thesis is the development of geometrical methods for the investigation of critical phenomena. In particular, a novel approach based on the Uhlmann curvature is introduced for the investigation of non-equilibrium steady-state quantum phase transitions (NESS-QPTs). Equilibrium phase transitions fall invariably into two markedly non-overlapping categories: classical phase transitions and quantum phase transitions. NESS-QPTs offer a unique arena where such a distinction fades off. We propose a method to reveal and quantitatively assess the quantum character of such critical phenomena. We apply this tool to a paradigmatic class of lattice fermion systems with local reservoirs, characterised by Gaussian non-equilibrium steady states. The relations between the behaviour of the Uhlmann curvature, the divergence of the correlation length, the character of the criticality and the dissipative gap are demonstrated. We argue that this tool can shade light upon the nature of non equilibrium steady state criticality in particular with regard to the role played by quantum vs classical fluctuations.
Quantum phase transition. Non-equilibrium phase transition. Geometric phase. Information geometry. Quantum information. Quantum parameter estimation.
GEOMETRY OF DISSIPATIVE PHASE TRANSITIONS.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/265982
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