Based on the recent paper (Phys. Rev. Lett. 102, 216803, (2009)), we study the nonequilibrium occupation number and charge susceptibility of a resonance level close to a dissipative quantum phase transition of the Kosterlitz-Thouless (KT) type between a de-localized phase for weak dissipation and a localized phase for strong dissipation. The resonance level is coupled to two spinless fermionic baths with a finite bias voltage and an Ohmic bosonic bath representing the dissipative environment. The system is equivalent to an effective anisotropic Kondo model out of equilibrium. Within the nonequilibrium Renormalization Group (RG) approach, we calculate nonequilibrium magnetization and spin susceptibility in the effective Kondo model, corresponding to occupation number and charge susceptibility of a resonance level, respectively. We demonstrate the smearing of the KT transition in the nonequilibrium magnetization as a function of the effective anisotropic Kondo couplings, in contrast to a perfect jump in magnetization at the transition in equilibrium. In the limit of large bias voltages, we find both quantities at the KT transition and in the localized phase show deviations from the equilibrium Curie-law behavior. As the system gets deeper in the localized phase, both quantities decrease more rapidly to zero with increasing bias voltages.
Nonequilibrium susceptibility in photoinduced Floquet states is studied. We analyze an electron system coupled with a heat bath in a time-periodic oscillating electric field. Spin/charge susceptibility is formulated on the basis of the Floquet Green function method, and is calculated numerically in a wide range of amplitude and frequency of light. When the frequency is larger than the bandwidth, the susceptibility is enhanced due to the dynamical localization effect, and their peak positions in the momentum space are shifted by the Fermi surface deformation. In the case of the small frequency …
We study critical phenomena of nonequilibrium phase transitions by using the AdS/CFT correspondence. Our system consists of charged particles interacting with a heat bath of neutral gauge particles. The system is in current-driven nonequilibrium steady state, and the nonequilibrium phase transition is associated with nonlinear electric conductivity. We define a susceptibility as a response of the system to the current variation. We further define a critical exponent from the power-law divergence of the susceptibility. We find that the critical exponent and the critical amplitude ratio of the s…
Nonequilibrium transport through an interacting monitored quantum dot
Institute of Theoretical and Computational Physics, Graz University of Technology（格拉茨工业大学理论与计算物理研究所）；JEIP, UAR 3573 CNRS, Collège de France, PSL Research University（法国国家科学研究中心联合研究单位3573 JEIP，法兰西学院，巴黎文理研究大学）
Metal-insulator transition was microscopically investigated by orbital-resolved nuclear magnetic resonance (OR-NMR) spectroscopy in a single crystal of vanadium dioxide VO$_2$. Observations of the anisotropic $^{51}$V Knight shift and the nuclear quadrupole frequency allow us to evaluate orbital-dependent spin susceptibility and $d$ orbital occupations. The result is consistent with the degenerated $t_{2g}$ orbitals in a correlated metallic phase and the $d$ orbital ordering in a nonmagnetic insulating phase. The predominant orbital pointing along the chain facilitates a spin-singlet formation…
Local spin fluctuations provide the glue for orbital-singlet spin-triplet pairing in the doped Mott insulating regime of multi-orbital Hubbard models. At large Hubbard repulsion $U$, the pairing susceptibility is nevertheless very low, because the pairing interaction cannot overcome the suppression of charge fluctuations. Using nonequilibrium dynamical mean field simulations of the two-orbital Hubbard model, we show that out of equilibrium the pairing susceptibility in this large-$U$ regime can be strongly enhanced by creating a photo-induced population of the relevant charge states, and that …
We perform an ab-initio comparison between nonequilibrium dynamical mean-field theory and optical lattice experiments by studying the time evolution of double occupations in the periodically driven Fermi-Hubbard model. For off-resonant driving, the range of validity of a description in terms of an effective static Hamiltonian is determined and its breakdown due to energy absorption close to resonance is demonstrated. For near-resonant driving, we investigate the response to a change in driving amplitude and discover an asymmetric excitation spectrum with respect to the detuning. In general, we…
This comment clarifies the mixed definition of the cerium valence in the article entitled: Quantitative study of the $f$ occupation in CeMIn5 and other cerium compounds with hard X-rays, published in Journal of Electron Spectroscopy and Related Phenomena http://www.sciencedirect.com/science/article/pii/S0368204816300123 and available on arXiv:1601.03270. Indeed, it is unclear wether electrons belonging on hybridized f-states are part or not of the valence. When one tries to simulate the system, an Anderson impurity model only includes valence bands electrons and localized 4-f states. Therefore…
A quantum critical behavior of the magnetic susceptibility was observed in a quasicrystal containing ytterbium. At the same time, a mixed-valence feature of Yb ions was reported, which appears to be incompatible with the magnetic instability. We derive the magnetic susceptibility by expressing the quasiperiodicity as the distributed hybridization strength between Yb 4f and conduction electrons. Assuming a wide distribution of the hybridization strength, the most f electrons behave as renormalized paramagnetic states in the Kondo or mixed-valence regime, but a small number of f moments remain u…
We study the Hall conductance of a Chern insulator after a global quench of the Hamiltonian. The Hall conductance in the long time limit is obtained by applying the linear response theory to the diagonal ensemble. It is expressed as the integral of the Berry curvature weighted by the occupation number over the Brillouin zone. We identify a topologically driven nonequilibrium phase transition, which is indicated by the nonanalyticity of the Hall conductance as a function of the energy gap m_f in the post-quench Hamiltonian H_f. The topological invariant for the quenched state is the winding num…
We study formation of local magnetic moments in strongly correlated Hubbard model within dynamical mean field theory and associate peculiarities of temperature dependence of local charge $χ_c$ and spin $χ_s$ susceptibilities with different stages of local moment formation. Local maximum of temperature dependence of the charge susceptibility $χ_c$ is associated with beginning of local magnetic moments formation, while the minimum of the susceptibility $χ_c$ and double occupation, as well as low temperature boundary of the plateau of effective local magnetic moment $μ_{\rm eff}^2=Tχ_s$ temperatu…
Quantum criticality and nonequilibrium dynamics on a Lieb lattice of Rydberg atoms
Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；University of Toronto（多伦多大学）；QuEra Computing Inc.（QuEra计算公司）；Princeton University（普林斯顿大学）
Linear response theory (LRT) is one of the main approaches to the dynamics of quantum many-body systems. However, this approach has limitations and requires, e.g., that the initial state is (i) mixed and (ii) close to equilibrium. In this paper, we discuss these limitations and study the nonequilibrium dynamics for a certain class of properly prepared initial states. Specifically, we consider thermal states of the quantum system in the presence of an additional static force which, however, become nonequilibrium states when this static force is eventually removed. While for weak forces the rela…
