scholarly journals Quantum discord and quantum phase transition in spin-1/2 frustrated Heisenberg chain

2013 ◽  
Vol 13 (5&6) ◽  
pp. 452-468
Author(s):  
Chu-Hui Fan ◽  
Heng-Na Xiong ◽  
Yixiao Huang ◽  
Zhe Sun
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Quantum Discord ◽  
Nearest Neighbor ◽  
Finite Size ◽  
Quantum Phase ◽  
Nonlinear Dependence ◽  
Heisenberg Chain ◽  
Transition Points ◽  
Analytical Result

By using the concept of the quantum discord (QD), we study the spin-1/2 antiferromagnetic Heisenberg chain with next-nearest-neighbor interaction. Due to the $SU(2)$ symmetry and $Z_{2}$ symmetry in this system, we obtain the analytical result of the QD and its geometric measure (GMQD), which is determined by the two-site correlators. For the 4-site and 6-site cases, the connection between GMQD (QD) and the eigenenergies was revealed. From the analytical and numerical results, we find GMQD (QD) is an effective tool in detecting the both the first-order and the infinite-order quantum-phase-transition points for the finite-size systems. Moreover, by using the entanglement excitation energy and a universal frustration measure we consider the frustration properties of the system and find a nonlinear dependence of the GMQD on the frustration.

scholarly journals Entanglement entropy in quasi-symmetric multi-qubit states

2015 ◽  
Vol 13 (02) ◽  
pp. 1550007 ◽  
Author(s):  
Zhi-Hua Li ◽  
An-Min Wang
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Entanglement Entropy ◽  
Ground States ◽  
Quantum Phase ◽  
Transition Points ◽  
Qubit States ◽  
Basis Vectors ◽  
Dicke States

We generalize the symmetric multi-qubit states to their q-analogs, whose basis vectors are identified with the q-Dicke states. We study the entanglement entropy in these states and find that entanglement is extruded towards certain regions of the system due to the inhomogeneity aroused by q-deformation. We also calculate entanglement entropy in ground states of a related q-deformed Lipkin–Meshkov–Glick (LMG) model and show that the singularities of entanglement can correctly signify the quantum phase transition points for different strengths of q-deformation.

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 Electrodynamics of Topologically Ordered Quantum Phases in Dirac Materials

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2914
Author(s):  
Musa A. M. Hussien ◽  
Aniekan Magnus Ukpong
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Ground State ◽  
Density Functional ◽  
Quantum States ◽  
Quantum Phase ◽  
Graphene Monolayer ◽  
Theoretic Approach ◽  
Dirac Materials ◽  
Transition Points

First-principles calculations of the electronic ground state in tantalum arsenide are combined with tight-binding calculations of the field dependence of its transport model equivalent on the graphene monolayer to study the emergence of topologically ordered quantum states, and to obtain topological phase diagrams. Our calculations include the degrees of freedom for nuclear, electronic, and photonic interactions explicitly within the quasistatic approximation to the time-propagation-dependent density functional theory. This field-theoretic approach allows us to determine the non-linear response of the ground state density matrix to the applied electromagnetic field at distinct quantum phase transition points. Our results suggest the existence of a facile electronic switch between trivial and topologically ordered quantum states that may be realizable through the application of a perpendicular electric or magnetic field alongside a staggered-sublattice potential in the underlying lattice. Signatures of the near field electrodynamics in nanoclusters show the formation of a quantum fluid phase at the topological quantum phase transition points. The emergent carrier density wave transport phase is discussed to show that transmission through the collective excitation mode in multilayer heterostructures is a unique possibility in plasmonic, optoelectronic, and photonic applications when atomic clusters of Dirac materials are integrated within nanostructures, as patterned or continuous surfaces.

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