Some basic aspects of quantum phase transitions

TL;DR

This paper reviews fundamental aspects of quantum phase transitions, focusing on quantum correlations, disorder effects, and various theoretical methods, while presenting new ideas and highlighting open problems in the field.

Contribution

It provides a comprehensive review of quantum phase transition theory using diverse statistical physics methods and introduces new ideas and results in the area.

Findings

Quantum correlations significantly influence phase transition properties.

Quenched disorder affects the nature of quantum phase transitions.

The paper presents new theoretical insights and discusses unresolved problems.

Abstract

Several basic problems of the theory of quantum phase transitions are reviewed. The effect of the quantum correlations on the phase transition properties is considered with the help of basic models of statistical physics. The effect of quenched disorder on the quantum phase transitions is also discussed. The review is performed within the framework of the thermodynamic scaling theory and by the most general methods of statistical physics for the treatment of phase transitions: general length-scale arguments, exact solutions, mean field approximation, Hubbard-Stratonovich transformation, Feynman path integral approach, and renormalization group in the field theoretical variant. Some new ideas and results are presented. Outstanding theoretical problems are mentioned.