scholarly journals Exceptional dynamical quantum phase transitions in periodically driven systems

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ryusuke Hamazaki
Keyword(s):  
Free Energy ◽  
Phase Transitions ◽  
Fundamental Problem ◽  
Quantum Phase Transitions ◽  
Quantum Phase ◽  
Exceptional Point ◽  
Many Body ◽  
Periodically Driven ◽  
Time Regime ◽  
Short Time

AbstractExtending notions of phase transitions to nonequilibrium realm is a fundamental problem for statistical mechanics. While it was discovered that critical transitions occur even for transient states before relaxation as the singularity of a dynamical version of free energy, their nature is yet to be elusive. Here, we show that spontaneous symmetry breaking can occur at a short-time regime and causes universal dynamical quantum phase transitions in periodically driven unitary dynamics. Unlike conventional phase transitions, the relevant symmetry is antiunitary: its breaking is accompanied by a many-body exceptional point of a nonunitary operator obtained by space-time duality. Using a stroboscopic Ising model, we demonstrate the existence of distinct phases and unconventional singularity of dynamical free energy, whose signature can be accessed through quasilocal operators. Our results open up research for hitherto unknown phases in short-time regimes, where time serves as another pivotal parameter, with their hidden connection to nonunitary physics.

scholarly journals Interaction between Different Kinds of Quantum Phase Transitions

2021 ◽  
Vol 3 (2) ◽  
pp. 253-261
Author(s):  
Angel Ricardo Plastino ◽  
Gustavo Luis Ferri ◽  
Angelo Plastino
Keyword(s):  
Phase Transitions ◽  
Nuclear Physics ◽  
Body Problem ◽  
Quantum Phase Transitions ◽  
Quantum Phase ◽  
Exactly Solvable Models ◽  
Solvable Models ◽  
Many Body ◽  
Pairing Interaction ◽  
Exactly Solvable

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).

scholarly journals GEOMETRIC PHASES AND QUANTUM PHASE TRANSITIONS

2008 ◽  
Vol 22 (06) ◽  
pp. 561-581 ◽  
Author(s):  
SHI-LIANG ZHU
Keyword(s):  
Phase Transitions ◽  
Geometric Phase ◽  
Quantum Phase Transitions ◽  
Condensed Matter ◽  
Quantum Phase ◽  
Many Body ◽  
Scientific Communities ◽  
Geometric Phases ◽  
Many Body Systems ◽  
The Many

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.

scholarly journals Diagonal entropy in many-body systems: Volume effect and quantum phase transitions

2020 ◽  
Vol 384 (16) ◽  
pp. 126333
Author(s):  
Zhengan Wang ◽  
Zheng-Hang Sun ◽  
Yu Zeng ◽  
Haifeng Lang ◽  
Qiantan Hong ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Quantum Phase Transitions ◽  
Volume Effect ◽  
Quantum Phase ◽  
Many Body ◽  
Many Body Systems

scholarly journals MICROSCOPIC CALCULATIONS OF QUANTUM PHASE TRANSITIONS IN FRUSTRATED MAGNETIC LATTICES

2006 ◽  
Vol 20 (19) ◽  
pp. 2612-2623
Author(s):  
RAYMOND F. BISHOP ◽  
SVEN E. KRÜGER
Keyword(s):  
Phase Transitions ◽  
Quantum Monte Carlo ◽  
Quantum Phase Transitions ◽  
Quantum Phase ◽  
Cluster Method ◽  
Many Body ◽  
Many Body Theory ◽  
Body Theory ◽  
Quantum Monte Carlo Simulations ◽  
Spatial Continuum

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.

scholarly journals Quantum critical dynamics in a spinor Hubbard model quantum simulator

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Jared O. Austin ◽  
Zihe Chen ◽  
Zachary N. Shaw ◽  
Khan W. Mahmud ◽  
Yingmei Liu
Keyword(s):  
Phase Transitions ◽  
Hubbard Model ◽  
Quantum Phase Transitions ◽  
Three Dimensional ◽  
Quantum Phase ◽  
Critical Dynamics ◽  
Scaling Effects ◽  
Many Body ◽  
Quantum Simulator ◽  
Quantum Critical

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.

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