The notion of fidelity in quantum information science has been recently applied to analyze phase transitions from the viewpoint ground-state (GS) overlap for various many-body systems. In this work, we unveil intrinsic relation between GS and derivatives energy find that they play an equivalent role identifying transition. general connection two approaches enables us understand different singularity scaling behaviors exhibited systems on grounds. Our conclusions are illustrated via several...

A general method is proposed for constructing the Bethe ansatz equations of integrable models without U(1) symmetry. As an example, exact spectrum XXZ spin ring with a Möbius-like topological boundary condition derived by modified T-Q relation based on functional connection between eigenvalues transfer matrix and quantum determinant monodromy matrix. With solution, elementary excitations XX are discussed in detail. It found that excitation indeed shows nontrivial nature.

We study the competition of disorder and superconductivity for a one-dimensional p-wave superconductor in incommensurate potentials. With increase strength potential, system undergoes transition from topological superconducting phase to topologically trivial localized phase. The boundary is determined both numerically analytically various aspects characterized by presence Majorana edge fermions with open conditions. also calculate Z2 invariant bulk find it can be used distinguish different...

A one-dimensional Bose-Hubbard model with unidirectional hopping is shown to be exactly solvable. Applying the algebraic Bethe ansatz method, we prove integrability of and derive equations. The exact eigenvalue spectrum can obtained by solving these distribution roots reveals presence a superfluid-Mott insulator transition at ground state, critical point determined. By adjusting boundary parameter, demonstrate existence non-Hermitian skin effect even in interaction, but it completely...

We study the nonequilibrium spin transport through a quantum dot coupled to magnetic electrodes. A formula for spin-dependent current is obtained and applied discuss linear conductance magnetoresistance in interacting regime. show that Kondo resonance correlation-induced splitting of levels may be systematically controlled by internal magnetization As result, when electrodes are parallel configuration, characterized two spin-resolved peaks. Furthermore, presence spin-flip process splits into three

In this paper, we investigate the fidelity for Heisenberg chain with next-nearest-neighbor interaction (or J1-J2 model) and analyze its connections quantum phase transition. We compute between ground states find that transition point of model cannot be well characterized by ground-state finite-size systems. Instead, introduce calculate first excited states. Our results show can state even a small-size system.

We present an exact analytical solution of the fundamental systems quasi-one-dimensional spin-1/2 fermions with infinite repulsion for arbitrary confining potential. The eigenfunctions are constructed by combination Girardeau's hard-core contacting boundary condition and group theoretical method, which guarantees obtained states to be simultaneously eigenstates S S_{z} satisfy antisymmetry under odd permutation. show that total ground-state density profile behaves like polarized...

We study the Heisenberg antiferromagnet with single-ion anisotropy in two and three dimensions present self-consistent intuitive theory to show Bose-Einstein condensation-induced long-range order gapped magnetic systems, when energy gap is tuned zero by changing physical parameters or applying an external field. The recent experimental results on ${\mathrm{NiCl}}_{2}∙4\mathrm{SC}{({\mathrm{NH}}_{2})}_{2}$ are interpreted theory. Many other systems share same picture. also helpful...

The spin-1/2 XYZ model with both periodic and anti-periodic boundary conditions is studied via the off-diagonal Bethe ansatz method. exact spectra of Hamiltonians equations are derived by constructing inhomogeneous T-Q relations, which allow us to treat even N (the number lattice sites) odd cases simultaneously in an unified approach.

Iron-based superconductors exhibit many different antiferromagnetically ordered ground states. We construct a minimum effective magnetic model that displays all phases. This also captures three incommensurate phases as well, two of which have been observed experimentally. The characterizes the nature phase transitions between and explains variety properties, such spin-wave spectra electronic nematism. Most importantly, by unifying understanding magnetism, we cast insight on key ingredients...

In two previous papers [26], [27], the exact solutions of spin-12 chains with arbitrary boundary fields were constructed via off-diagonal Bethe ansatz (ODBA). Here we introduce a method to approach thermodynamic limit those models. The key point is that at sequence degenerate points crossing parameter η=ηm, equations (BAEs) can be reduced conventional ones. This allows us extrapolate formulae derived from BAEs η case O(N−2) corrections in N→∞. As an example, surface energy XXZ spin chain...

A bstract The thermodynamic limits of the XYZ spin chain with periodic or twisted boundary conditions are studied. By using technique characterizing eigenvalue transfer matrix by T − Q relation and zeros associated polynomial, we obtain constraints Bethe roots for eigenvalues. With help structure roots, distribution patterns zeros. Based on them, physical quantities such as surface energy excitation calculated. We find that both them depend parity sites number due to topological long-range...

Based on the inhomogeneous T-Q relation constructed via off-diagonal Bethe Ansatz, Bethe-type eigenstates of XXZ spin-1/2 chain with arbitrary boundary fields are constructed. It is found that by employing two sets gauge transformations, proper generators and reference state for constructing vectors can be obtained respectively. Given an eigenvalue, it proven resulting eigenstate transfer matrix, provided parameters satisfy associated Ansatz equations.

This work proposes an underwater wireless optical communication (UWOC) system based on computational temporal ghost imaging (CTGI) and a low-bandwidth high-sensitivity avalanche photodiode. After measuring the attenuation coefficient of water, series neutral density filters is used to attenuate power estimate distance UWOC. Experimental results show that under conditions 4 GHz transmitting frequency 144.37 m estimated distance, through CTGI, we can achieve error-free transmission, peak...

An integrable spin-ladder model with nearest-neighbor exchanges and biquadratic interactions is proposed. With the Bethe ansatz solutions of Hamiltonian, it found that there are three possible phases in ground state, i.e., a rung-dimerized phase spin gap, two massless phases. The fixed points system quantum critical behavior at point ${J=J}_{+}^{c}$ discussed.

We propose an integrable Kondo problem in a one-dimensional $t\ensuremath{-}J$ model. With the open boundary condition of wave functions at impurity sites, model can be exactly solved via Bethe ansatz for set ${J}_{L,R}$ (Kondo coupling constants) and ${V}_{L,R}$ (impurity potentials) parametrized by single parameter $c$. The value runs from negative infinity to positive infinity, which allows us study both ferromagnetic antiferromagnetic strongly correlated electron system. Generally, there...

We report the thickness-dependent (in terms of atomic layers) oscillation behavior perpendicular upper critical field ${H}_{c2\ensuremath{\perp}}$ in ultrathin lead films at reduced temperature ($t=T/{T}_{c}$). Distinct oscillations normal-state resistivity as a function film thickness have also been observed. Compared with ${T}_{c}$ oscillation, shows considerable large amplitude and $\ensuremath{\pi}$ phase shift. The oscillatory mean free path caused by quantum size effect plays role oscillation.

For the ballistic quantum transport, conductance of each channel is quantized to a value ${2e}^{2}/h.$ In presence defects, electrons will be scattered such that deviate from values conductance. We show an antiresonance scattering can occur when extra defect level introduced into conduction band. At scattering, exactly one one-dimensional wire disappears, in good agreement with ab initio calculations. The takes nonzero Fermi energy away scattering.

We present the study of Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairing states in $p$-orbital bands both two and three-dimensional optical lattices. Due to quasi one-dimensional band structure which arises from unidirectional hopping orthogonal $p$-orbitals, phase space is not affected by spin imbalance. Furthermore, interactions build up high dimensional coherence stabilizes FFLO 2D 3D lattices a large parameter regime diagram. These phases are stable with imposing inhomogeneous trapping...