We consider a strongly interacting quantum dot connected to two leads held at quite different temperatures. Our aim is to study the behavior of the Kondo effect in the presence of large thermal biases. We use three different approaches, namely, a perturbation formalism based on the Kondo Hamiltonian, a slave-boson mean-field theory for the Anderson model at large charging energies and a truncated equation-of-motion approach beyond the Hartree-Fock approximation. The two former formalisms yield a suppression of the Kondo peak for thermal gradients above the Kondo temperature, showing a remarkably good agreement despite their different ranges of validity. The third technique allows us to analyze the full density of states within a wide range of energies. Additionally, we have investigated the quantum transport properties (electric current and thermocurrent) beyond linear response. In the voltage-driven case, we reproduce the split differential conductance due to the presence of different electrochemical potentials. In the temperature-driven case, we observe a strongly nonlinear thermocurrent as a function of the applied thermal gradient. Depending on the parameters, we can find nontrivial zeros in the electric current for finite values of the temperature bias. Importantly, these thermocurrent zeros yield direct access to the system's characteristic energy scales (Kondo temperature and charging energy).
Consistent bosonization-debosonization II: The two-lead Kondo problem and the fate of its non-equilibrium Toulouse point
随着一个方案的发展,玻色化和去玻色化一致[N。Shah和C.J.Bolech,Phys.Rev B 93,085440(2016); arXiv:1508.03078],我们详细介绍了双引线近藤结模型的图卢兹点解析解。可解点的存在性和位置没有改变,但计算方法和观测量的最终表达式与已有结果相比有明显的变化。这个可解点是相关系统中非平衡输运的极少数精确结果之一。它产生相对简单的解析表达式的电流在整个范围内的温度,磁场和电压。它还显示了精确的,在图卢兹微调的限制,如何运输演变取决于铅间和铅内近藤交换耦合的相对强度从弱到强。因此,对它的进一步了解是未来研究的重要基石。
Nonperturbative approach to quench dynamics. II. Universal electric current of the nonequilibrium Kondo model
在前一篇文章中,我们发现了在偏压驱动下的非平衡Kondo模型中失超后的平均电流的级数表达式。在这里,我们评估的稳态电流的强耦合和弱耦合的制度。我们在通常的弱反铁磁区得到了标准的首阶结果,并且我们还发现了一个新的具有Kondo温度的强铁磁耦合区$T_K = D e^{\frac{3π^2}{8} ρJ}$。在这种情况下,微分电导$dI/dV$在大电压或温度下渐近地达到么正性极限$2e^2/h$。
Experimental Evidence of Fractional Entropy in Critical Kondo Systems
Université Paris-Saclay(巴黎萨克雷大学);CNRS(法国国家科学研究中心);Centre de Nanosciences et de Nanotechnologies(纳米科学与纳米技术中心);University College Dublin(都柏林大学学院);Centre for Quantum Engineering, Science, and Technology(量子工程、科学与技术中心);Université Paris Cité(巴黎西岱大学)
Cooper pair charge Kondo effect in a hybrid quantum dot - superconductor device
SISSA(的里雅斯特国际高等研究学院);INFN Sezione di Trieste(意大利国家核物理研究所的里雅斯特分部);Dipartimento di Fisica e Astronomia “G. Galilei”, Università degli Studi di Padova(帕多瓦大学伽利略物理与天文系);Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Padova(意大利国家核物理研究所帕多瓦分部);Dipartimento di Fisica dell’Università di Pisa and INFN, sezione di Pisa(比萨大学物理系及意大利国家核物理研究所比萨分部)
Many-body wavefunctions for quantum impurities out of equilibrium. I. The nonequilibrium Kondo model
我们在这里介绍一个方法的细节[A. B.卡尔弗和N. Andrei,Phys. Rev. B 103,L201103(2021)],用于计算局部猝灭后的时间相关多体波函数。我们应用该方法的电压驱动的非平衡Kondo模型,以找到确切的时间演化波函数淬火后,点突然连接到引线在$t=0$。该方法不使用Bethe模,也适用于其它量子杂质模型,可能具有更广泛的适用性。我们证明了Kondo模型随时间演化的波函数的长时间极限(首先将系统尺寸取为无穷大)是满足Lippmann-Schwinger方程的载流非平衡稳态。我们表明,电流的时间演化波函数给出了一个系列的表达,可以扩大无论是在弱耦合或强耦合,收敛到所有的订单在任何情况下的稳态极限。该系列同意领先的顺序与已知的结果在弱反铁磁耦合的研究制度,也揭示了一个普遍的制度强铁磁耦合与近藤温度$T_K^{(F)} = D e^{-\frac{3π^2}{8} ρ|J|}$($J<0$,$ρ|J|\to\infty$)。在这种情况下,微分电导$dI/dV$在大电压或温度下渐近地达到么正性极限$2e^2/h$。
Discovery of an Antiferromagnetic Topological Nodal-line Kondo Semimetal
Beijing Normal University(北京师范大学);Zhejiang University(浙江大学);Donostia International Physics Center (DIPC)(多诺斯蒂亚国际物理中心);University of Oxford(牛津大学);Diamond Light Source(钻石光源);Institute of Physics, Chinese Academy of Sciences(中国科学院物理研究所);Nanjing University(南京大学);ShanghaiTech University(上海科技大学);Tsinghua University(清华大学);MAX IV Laboratory, Lund University(隆德大学MAX IV实验室);Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory(斯坦福同步辐射光源,SLAC国家加速器实验室);Swiss Light Source, Paul Scherrer Institute(瑞士光源,保罗谢尔研究所);Tokyo Institute of Technology(东京工业大学);Princeton University(普林斯顿大学)