اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدStability of ground state degeneracy to long-range interactions
120
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We show that some gapped quantum many-body systems have a ground state degeneracy that is stable to long-range (e.g., power-law) perturbations, in the sense that any ground state energy splitting induced by such perturbations is exponentially small in the system size. More specifically, we consider an Ising symmetry-breaking Hamiltonian with several exactly degenerate ground states and an energy gap, and we then perturb the system with Ising symmetric long-range interactions. For these models we prove (1) the stability of the gap, and (2) that the residual splitting of the low-energy states below the gap is exponentially small in the system size. Our proof relies on a convergent polymer expansion that is adapted to handle the long-range interactions in our model. We also discuss applications of our result to several models of physical interest, including the Kitaev p-wave wire model perturbed by power-law density-density interactions with an exponent greater than 1.
قيم البحث
اقرأ أيضاً
We investigate the thermal and transport properties of CexLa1-xRu2Al10 to clarify the origin of the recently discovered mysterious phase below T0=27 K in CeRu2Al10 where a large magnetic entropy is released, however, the existence of an internal magn
etic field is ruled out by 27Al-NQR measurement. We find that T0 decreases with decreasing x and disappears at x~0.45. T0 of CeRu2Al10 is suppressed down to 26 K under H=14.5 T along the a-axis. These results clearly indicate that the transition has a magnetic origin and is ascribed to the interaction between Ce ions. Considering the results of specific heat, magnetic susceptibility, thermal expansion, and electrical resistivity and also 27Al NQR, we propose that the transition originates from the singlet pair formation between Ce ions. Although its properties in a Ce dilute region is basically understood by the impurity Kondo effect, CeRu2Al10 shows a Kondo-semiconductor-like behavior. The phase transition at T0 may be characterized as a new type of phase transition that appears during the crossover from the dilute Kondo to the Kondo semiconductor.
We study the thermodynamics and critical behavior of su($m|n$) supersymmetric spin chains of Haldane-Shastry type with a chemical potential term. We obtain a closed-form expression for the partition function and deduce a description of the spectrum i
n terms of the supersymmetric version of Haldanes motifs, which we apply to obtain an analytic expression for the free energy per site in the thermodynamic limit. By studying the low-temperature behavior of the free energy, we characterize the critical behavior of the chains with $1le m,nle2$, determining the critical regions and the corresponding central charge. We also show that in the su($2|1$), su($1|2$) and su($2|2$) chains the bosonic or fermionic densities can undergo first-order (discontinuous) phase transitions at $T=0$, in contrast with the previously studied su(2) case.
We have calculated the isotropic $C_6$ coefficients characterizing the long-range van der Waals interaction between two identical heteronuclear alkali-metal diatomic molecules in the same arbitrary vibrational level of their ground electronic state $
X^1Sigma^+$. We consider the ten species made up of $^7$Li, $^{23}$Na, $^{39}$K, $^{87}$Rb and $^{133}$Cs. Following our previous work [M.~Lepers textit{et.~al.}, Phys.~Rev.~A textbf{88}, 032709 (2013)] we use the sum-over-state formula inherent to the second-order perturbation theory, composed of the contributions from the transitions within the ground state levels, from the transition between ground-state and excited state levels, and from a crossed term. These calculations involve a combination of experimental and quantum-chemical data for potential energy curves and transition dipole moments. We also investigate the case where the two molecules are in different vibrational levels and we show that the Moelwyn-Hughes approximation is valid provided that it is applied for each of the three contributions to the sum-over-state formula. Our results are particularly relevant in the context of inelastic and reactive collisions between ultracold bialkali molecules, in deeply bound or in Feshbach levels.
In this paper, we consider the long time dynamics of radially symmetric solutions of nonlinear Schrodinger equations (NLS) having a minimal mass ground state. In particular, we show that there exist solutions with initial data near the minimal mass g
round state that oscillate for long time. More precisely, we introduce a coordinate defined near the minimal mass ground state which consists of finite and infinite dimensional part associated to the discrete and continuous part of the linearized operator. Then, we show that the finite dimensional part, two dimensional, approximately obeys Newtons equation of motion for a particle in an anharmonic potential well. Showing that the infinite dimensional part is well separated from the finite dimensional part, we will have long time oscillation.
The magnetic ground state of the hyper-kagome lattice in Na4Ir3O8 is explored via combined bulk magnetization, muon spin relaxation, and neutron scattering measurements. A short-range, frozen, state comprised of quasi-static moments develops below a
characteristic temperature of T_F=6 K, revealing an inhomogeneous distribution of spins occupying the entirety of the sample volume. Quasi-static, short-range, spin correlations persist until at least 20 mK and differ substantially from the nominally dynamic response of a quantum spin liquid. Our data demonstrate that an inhomogeneous magnetic ground state arises in Na4Ir3O8 driven either by disorder inherent to the creation of the hyper-kagome lattice itself or stabilized via quantum fluctuations.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
