scholarly journals Fermion condensation quantum phase transition versus conventional quantum phase transitions

2004 ◽  
Vol 329 (1-2) ◽  
pp. 108-115 ◽  
Author(s):  
V.R. Shaginyan ◽  
J.G. Han ◽  
J. Lee
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Quantum Phase Transition ◽  
Quantum Phase Transitions ◽  
Quantum Phase

scholarly journals Observation of generalized Kibble-Zurek mechanism across a first-order quantum phase transition in a spinor condensate

2020 ◽  
Vol 6 (21) ◽  
pp. eaba7292
Author(s):  
L.-Y. Qiu ◽  
H.-Y. Liang ◽  
Y.-B. Yang ◽  
H.-X. Yang ◽  
T. Tian ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Power Law ◽  
Quantum Phase Transition ◽  
Scaling Laws ◽  
Quantum Phase Transitions ◽  
Quantum Phase ◽  
Polar Phase ◽  
First Order ◽  
Spin Excitations

The Kibble-Zurek mechanism provides a unified theory to describe the universal scaling laws in the dynamics when a system is driven through a second-order quantum phase transition. However, for first-order quantum phase transitions, the Kibble-Zurek mechanism is usually not applicable. Here, we experimentally demonstrate and theoretically analyze a power-law scaling in the dynamics of a spin-1 condensate across a first-order quantum phase transition when a system is slowly driven from a polar phase to an antiferromagnetic phase. We show that this power-law scaling can be described by a generalized Kibble-Zurek mechanism. Furthermore, by experimentally measuring the spin population, we show the power-law scaling of the temporal onset of spin excitations with respect to the quench rate, which agrees well with our numerical simulation results. Our results open the door for further exploring the generalized Kibble-Zurek mechanism to understand the dynamics across first-order quantum phase transitions.

scholarly journals Quantum phase transitions of strongly correlated metals

2020 ◽  
pp. 6-13
Author(s):  
Martha Yolima Suárez Villagrán ◽  
Nikolaos Mitsakos ◽  
John H. Miller Jr
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Critical Temperature ◽  
Quantum Phase Transition ◽  
Open Problem ◽  
Quantum Phase Transitions ◽  
Quantum Phase ◽  
Strongly Correlated ◽  
Made In

In this article, we discuss several aspects of the quantum phase transition, with special emphasis on the metalinsulator transition. We start with a review of key experimental and theoretical works and then discuss how doping a system reduces the critical temperature of the overall phase transition. Although many aspects of the quantum phase transition still remain an open problem, onsiderable progress has been made in revealing the underlying physics, both theoretically and experimentally.

scholarly journals Topological Frustration can modify the nature of a Quantum Phase Transition

2021 ◽  
Author(s):  
Vanja Marić ◽  
Gianpaolo Torre ◽  
Fabio Franchini ◽  
Salvatore Giampaolo
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Quantum Phase Transition ◽  
Landau Theory ◽  
Continuous Phase ◽  
Quantum Systems ◽  
Quantum Phase ◽  
Local Order ◽  
Ginzburg Landau ◽  
One Dimensional

Abstract Ginzburg-Landau theory of continuous phase transitions implicitly assumes that microscopic changes are negligible in determining the thermodynamic properties of the system. In this work we provide an example that clearly contrasts with this assumption. In particular, we consider the 2-cluster-Ising model, a one-dimensional spin-1/2 system that is known to exhibit a quantum phase transition between a magnetic and a nematic phase. By imposing boundary conditions that induce topological frustration we show that local order is completely destroyed on both sides of the transition and that the two thermodynamic phases can only be characterized by string order parameters. Having proved that topological frustration is capable of altering the nature of a system's phase transition, this result is a clear challenge to current theories of phase transitions in complex quantum systems.

scholarly journals SCALING OF VON NEUMANN ENTROPY AT THE ANDERSON TRANSITION

2010 ◽  
Vol 24 (12n13) ◽  
pp. 1823-1840 ◽  
Author(s):  
Sudip Chakravarty
Keyword(s):  
Phase Transition ◽  
Wave Function ◽  
Phase Transitions ◽  
Ground State ◽  
Quantum Phase Transitions ◽  
Quantum Phase ◽  
Tuning Parameter ◽  
Von Neumann Entropy ◽  
Von Neumann ◽  
Anderson Transition

Extensive body of work has shown that for the model of a non-interacting electron in a random potential there is a quantum critical point for dimensions greater than two — a metal–insulator transition. This model also plays an important role in the plateau-to-plateu transition in the integer quantum Hall effect, which is also correctly captured by a scaling theory. Yet, in neither of these cases the ground state energy shows any non-analyticity as a function of a suitable tuning parameter, typically considered to be a hallmark of a quantum phase transition, similar to the non-analyticity of the free energy in a classical phase transition. Here we show that von Neumann entropy (entanglement entropy) is non-analytic at these phase transitions and can track the fundamental changes in the internal correlations of the ground state wave function. In particular, it summarizes the spatially wildly fluctuating intensities of the wave function close to the criticality of the Anderson transition. It is likely that all quantum phase transitions can be similarly described.

scholarly journals Classical and Quantum Signatures of Quantum Phase Transitions in a (Pseudo) Relativistic Many-Body System

2020 ◽  
Vol 5 (2) ◽  
pp. 26
Author(s):  
Maximilian Nitsch ◽  
Benjamin Geiger ◽  
Klaus Richter ◽  
Juan-Diego Urbina
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Quantum Phase Transitions ◽  
Mean Field ◽  
Finite Size ◽  
Quantum Phase ◽  
Effective Model ◽  
Field Analysis ◽  
Many Body ◽  
Linear Dispersion

We identify a (pseudo) relativistic spin-dependent analogue of the celebrated quantum phase transition driven by the formation of a bright soliton in attractive one-dimensional bosonic gases. In this new scenario, due to the simultaneous existence of the linear dispersion and the bosonic nature of the system, special care must be taken with the choice of energy region where the transition takes place. Still, due to a crucial adiabatic separation of scales, and identified through extensive numerical diagonalization, a suitable effective model describing the transition is found. The corresponding mean-field analysis based on this effective model provides accurate predictions for the location of the quantum phase transition when compared against extensive numerical simulations. Furthermore, we numerically investigate the dynamical exponents characterizing the approach from its finite-size precursors to the sharp quantum phase transition in the thermodynamic limit.

scholarly journals Spherical model and quantum phase transitions

2021 ◽  
Vol 2094 (2) ◽  
pp. 022027
Author(s):  
V N Udodov
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Critical Temperature ◽  
Critical Exponents ◽  
Quantum Phase Transitions ◽  
Dimensional Space ◽  
Spherical Model ◽  
Quantum Phase ◽  
Two Dimensional ◽  
Epsilon Expansion

Abstract The spherical Berlin-Katz model is considered in the framework of the epsilon expansion in one-dimensional and two-dimensional space. For the two-dimensional and threedimensional cases in this model, an exact solution was previously obtained in the presence of a field, and for the two-dimensional case the critical temperature is zero, that is, a “quantum” phase transition is observed. On the other hand, the epsilon expansion of critical exponents with an arbitrary number of order parameter components is known. This approach is consistent with the scaling paradigm. Some critical exponents are found for the spherical model in one-and twodimensional space in accordance with the generalized scaling paradigm and the ideas of quantum phase transitions. A new formula is proposed for the critical heat capacity exponent, which depends on the dynamic index z, at a critical temperature equal to zero. An expression is proposed for the order of phase transition with a change in temperature (developing the approach of R. Baxter), which also depends on the z index. An interpolation formula is presented for the effective dimension of space, which is valid for both a positive critical temperature and a critical temperature equal to zero. This formula is general. Transitions with a change in the field in a spherical model at absolute zero are also considered.

TOPOLOGICAL QUANTUM PHASE TRANSITIONS IN TWO-DIMENSIONAL HEXAGONAL LATTICE BILAYERS

SPIN ◽  
2013 ◽  
Vol 03 (02) ◽  
pp. 1330006 ◽  
Author(s):  
XUECHAO ZHAI ◽  
GUOJUN JIN
Keyword(s):  
Phase Transition ◽  
Band Gap ◽  
Quantum Phase Transition ◽  
Quantum Phase Transitions ◽  
Hexagonal Lattice ◽  
Short Review ◽  
Quantum Phase ◽  
Two Dimensional ◽  
Topological Quantum ◽  
Bulk Band

Since the successful fabrication of graphene, two-dimensional hexagonal lattice structures have become a research hotspot in condensed matter physics. In this short review, we theoretically focus on discussing the possible realization of a topological insulator (TI) phase in systems of graphene bilayer (GBL) and boron nitride bilayer (BNBL), whose band structures can be experimentally modulated by an interlayer bias voltage. Under the bias, a band gap can be opened in AB-stacked GBL but is still closed in AA-stacked GBL and significantly reduced in AA- or AB-stacked BNBL. In the presence of spin–orbit couplings (SOCs), further demonstrations indicate whether the topological quantum phase transition can be realized strongly depends on the stacking orders and symmetries of structures. It is observed that a bulk band gap can be first closed and then reopened when the Rashba SOC increases for gated AB-stacked GBL or when the intrinsic SOC increases for gated AA-stacked BNBL. This gives a distinct signal for a topological quantum phase transition, which is further characterized by a jump of the ℤ2 topological invariant. At fixed SOCs, the TI phase can be well switched by the interlayer bias and the phase boundaries are precisely determined. For AA-stacked GBL and AB-stacked BNBL, no strong TI phase exists, regardless of the strength of the intrinsic or Rashba SOCs. At last, a brief overview is given on other two-dimensional hexagonal materials including silicene and molybdenum disulfide bilayers.

Quantum phase transitions in composite matrix product states of one-dimensional spin-1/2 chains

2015 ◽  
Vol 29 (09) ◽  
pp. 1550071 ◽  
Author(s):  
Jing-Min Zhu
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Long Range ◽  
Quantum Correlation ◽  
Quantum Phase Transitions ◽  
Ferromagnetic State ◽  
Quantum Phase ◽  
Matrix Product ◽  
One Dimensional ◽  
Matrix Product States

For matrix product states of one-dimensional spin-1/2 chains, we investigate the properties of quantum phase transition of the proposed composite system. We find that the system has three different ferromagnetic phases, one line of the two ferromagnetic phases coexisting equally describes the paramagnetic state, and the other two lines of two ferromagnetic phases coexisting equally describe the ferrimagnetic states, while the three phases coexisting equally point describes the ferromagnetic state. Whether on phase transition lines or at the phase transition point, the system is always in an isolated mediate-coupling state, the physical quantities are discontinuous and the system has long-range correlation and has long-range classical correlation and long-range quantum correlation. We believe that our work is helpful for comprehensively and profoundly understanding the quantum phase transitions, and of some certain guidance and enlightening on the classification and measure of quantum correlation of quantum many-body systems.

scholarly journals Multi-critical topological transition at quantum criticality

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ranjith R. Kumar ◽  
Y. R. Kartik ◽  
S. Rahul ◽  
Sujit Sarkar
Keyword(s):  
Phase Transition ◽  
Critical Point ◽  
Quantum Phase Transition ◽  
Quantum Phase Transitions ◽  
Lorentz Invariance ◽  
Quantum Phase ◽  
Spin Interaction ◽  
Curvature Function ◽  
Topological Transition ◽  
Topological Quantum

AbstractThe investigation and characterization of topological quantum phase transition between gapless phases is one of the recent interest of research in topological states of matter. We consider transverse field Ising model with three spin interaction in one dimension and observe a topological transition between gapless phases on one of the critical lines of this model. We study the distinct nature of these gapless phases and show that they belong to different universality classes. The topological invariant number (winding number) characterize different topological phases for the different regime of parameter space. We observe the evidence of two multi-critical points, one is topologically trivial and the other one is topologically active. Topological quantum phase transition between the gapless phases on the critical line occurs through the non-trivial multi-critical point in the Lifshitz universality class. We calculate and analyze the behavior of Wannier state correlation function close to the multi-critical point and confirm the topological transition between gapless phases. We show the breakdown of Lorentz invariance at this multi-critical point through the energy dispersion analysis. We also show that the scaling theories and curvature function renormalization group can also be effectively used to understand the topological quantum phase transitions between gapless phases. The model Hamiltonian which we study is more applicable for the system with gapless excitations, where the conventional concept of topological quantum phase transition fails.

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