Metastable quantum phase transitions in a periodic one-dimensional Bose gas. II. Many-body theory

2010 ◽  
Vol 81 (2) ◽  
Author(s):  
R. Kanamoto ◽  
L. D. Carr ◽  
M. Ueda
2006 ◽  
Vol 20 (19) ◽  
pp. 2612-2623
Author(s):  
RAYMOND F. BISHOP ◽  
SVEN E. KRÜGER

It is nowadays acknowledged that the coupled cluster method (CCM) provides one of the most powerful and most widely used of all ab initio techniques of microscopic quantum many-body theory. It has been applied to a broad range of both finite and extended physical systems defined on a spatial continuum, where it has generally yielded numerical results which are among the most accurate available. This widespread success has spurred many recent applications to quantum systems defined on a lattice. We discuss here a typical example of a two-dimensional spin-half Heisenberg magnet with two kinds of competing nearest-neighbour bonds. We show how the CCM can successfully describe the influence of strong quantum fluctuations on the zero-temperature phases and their quantum phase transitions. The model shows how the CCM can successfully describe the effects of competition between magnetic bonds with and without the presence of frustration. The frustrated case is particulary important since many other methods, including quantum Monte Carlo simulations, typically fail in this regime.


2021 ◽  
Vol 3 (2) ◽  
pp. 253-261
Author(s):  
Angel Ricardo Plastino ◽  
Gustavo Luis Ferri ◽  
Angelo Plastino

We employ two different Lipkin-like, exactly solvable models so as to display features of the competition between different fermion–fermion quantum interactions (at finite temperatures). One of our two interactions mimics the pairing interaction responsible for superconductivity. The other interaction is a monopole one that resembles the so-called quadrupole one, much used in nuclear physics as a residual interaction. The pairing versus monopole effects here observed afford for some interesting insights into the intricacies of the quantum many body problem, in particular with regards to so-called quantum phase transitions (strictly, level crossings).


2021 ◽  
Vol 103 (14) ◽  
Author(s):  
Xiaowen Zhang ◽  
Zheng He ◽  
Yiqing Hao ◽  
Yao Shen ◽  
Shoudong Shen ◽  
...  

2008 ◽  
Vol 22 (06) ◽  
pp. 561-581 ◽  
Author(s):  
SHI-LIANG ZHU

Quantum phase transition is one of the main interests in the field of condensed matter physics, while geometric phase is a fundamental concept and has attracted considerable interest in the field of quantum mechanics. However, no relevant relation was recognized before recent work. In this paper, we present a review of the connection recently established between these two interesting fields: investigations in the geometric phase of the many-body systems have revealed the so-called "criticality of geometric phase", in which the geometric phase associated with the many-body ground state exhibits universality, or scaling behavior in the vicinity of the critical point. In addition, we address the recent advances on the connection of some other geometric quantities and quantum phase transitions. The closed relation recently recognized between quantum phase transitions and some of the geometric quantities may open attractive avenues and fruitful dialogue between different scientific communities.


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