A quantum critical trio: Solvable models of finite temperature crossovers near quantum phase transitions

Author(s):  
Subir Sachdev
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 4 (1) ◽  
Author(s):  
Jared O. Austin ◽  
Zihe Chen ◽  
Zachary N. Shaw ◽  
Khan W. Mahmud ◽  
Yingmei Liu

AbstractThree-dimensional (3D) strongly correlated many-body systems, especially their dynamics across quantum phase transitions, are prohibitively difficult to be numerically simulated. We experimentally demonstrate that such complex many-body dynamics can be efficiently studied in a 3D spinor Bose–Hubbard model quantum simulator, consisting of antiferromagnetic spinor Bose–Einstein condensates confined in cubic optical lattices. We find dynamics and scaling effects beyond the scope of existing theories at superfluid–insulator quantum phase transitions, and highlight spin populations as a good observable to probe the quantum critical dynamics. Our data indicate that the scaling exponents are independent of the nature of the quantum phase transitions. We also conduct numerical simulations in lower dimensions using time-dependent Gutzwiller approximations, which qualitatively describe our observations.


2020 ◽  
pp. 2150002
Author(s):  
Biaoliang Ye ◽  
Zhanjun Zhang

In this paper, we explore the quantum phase transitions in the XY chain and the XXZ model. The quantum correlated coherence has been introduced by Tan and Jeong [Phys. Rev. Lett. 121, 220401 (2018)]. We utilize the quantum correlated coherence to investigate the quantum critical systems. We also demonstrate the Hellinger distance which shows the quantum critical behaviors. The numerical results are presented and analyzed in details.


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