visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
날짜 2016-09-21 16:00 
일시 4pm, Sep. 21 (Wed. 
장소 E6-2. #2502(2nd fl.) 
연사 Dr. Henrik Johannesson , University of Gothenburg (Sweden) and Beijing Computational Science Research Center (China) 

Entanglement probe of two-impurity Kondo physics

 

4pm, Sep. 21 (Wed.), E6-2. #2502(2nd fl.)
Dr. Henrik Johannesson , University of Gothenburg (Sweden) and Beijing Computational Science Research Center (China)


The two-impurity Kondo model has bearings on a number of topical problems, from heavy-fermion physics to spin-based quantum computing. In this talk I will review what is known about the model and also present a novel approach to its study, initiated in a collaboration with A. Bayat, S. Bose, and P. Sodano [1]. Specifically, we propose that real-space properties of the model can be obtained from an effective spin model where two single-impurity Kondo spin chains are joined via an RKKY interaction between the two impurity spins. We then use the Density Matrix Renormalization Group (DMRG) to study its features, using two complementary quantum-entanglement measures, the negativity and the von Neumann entropy. This nonperturbative approach enables us to uncover the Kondo screening cloud and its enhancement in the limit of large ferromagnetic RKKY coupling, thus corroborating a long-standing conjecture of ”Kondo resonance narrowing" for effectively large impurity spins. In a follow-up work [2], we extended our approach to study the entanglement spectrum of the model, and obtained the Schmidt gap, i.e. the difference between the two largest eigenvalues of the reduced density matrix. The Schmidt gap is found to signal the quantum phase transition between the Kondo and RKKY phases, in effect serving as an order parameter, correctly predicting the known scaling exponent for the Kondo crossover length at the critical point. Time permitting, I will briefly discuss also some more recent applications of our approach, to the study of local quantum quenches [3], the entanglement structure of the two-channel Kondo model [4], and impurity quantum thermodynamics [5].

 

[1] A. Bayat et al., Phys. Rev. Lett. 109, 066403 (2012)
[2] A. Bayat et al., Nat. Comm. 5, 3784 (2014)
[3] A. Bayat et al., Phys. Rev. B 92, 155141 (2015)
[4] B. Alkurtass et al., Phys. Rev. B 93, 081106(R) (2016)
[5] A. Bayat et al., Phys. Rev. B 93, 201106(R) (2016)

Contact: Heung Sun Sim, Physics Dept., (hs_sim@kaist.ac.kr)

번호 날짜 장소 제목
502 2016-07-08 11:00  #1323(E6-2. 1st fl.)  Isostatic magnetism
501 2016-11-11 13:30  #1323(E6-2. 1st fl.)  Bandgap Engineering of Black Phosphorus
500 2016-07-07 14:00  #1323(E6-2. 1st fl.)  Let there be topological superconductors
499 2017-02-01 14:00  #1323(E6-2. 1st fl.)  Quantum electron optics using flying electrons
498 2016-11-16 16:00  #1323(E6-2. 1st fl.)  Realizing Haldane Model in Fe-based Honeycomb Ferromagnetic Insulators
497 2018-10-19 10:00  #1323, E6-2  Energy conversion processes during magnetic reconnection in a laboratory plasma file
496 2018-05-31 16:00  #1323, E6-2  Dynamic control of optical properties with gated-graphene metamaterials file
495 2018-10-04 16:00  #1323, E6-2  Engineering light absorption in an ultrathin semiconductor metafilm file
494 2019-12-05 16:00  #1323, E6-2  Subwavelenth Photonic Devices: From Single Photon Sources to Solar Cell file
493 2019-10-15 16:00  #1323, E6-2  Moiré superlattices and graphene quasicrystal file
492 2018-10-16 10:00  #1323, E6-2  Capturing protein cluster dynamics and gene expression output in live cells file
491 2019-11-05 16:00  #1323, E6-2  Study on nanomaterials by the development of ultrahigh resolution laser-photoelectron microscopy (PEEM) file
490 2018-11-01 16:00  #1323, E6-2  Direct holography from a single snapshot file
489 2019-12-18 16:00  #1323, E6-2  Road to Higher Tc Superconductivity file
488 2018-05-09 16:00  #1323, E6-2  Recent advances in thermoelectric bulk composites file
487 2018-11-21 15:00  #1323, E6-2  Engineering topological quantum physics at the atomic scale file
486 2018-10-11 16:00  #1323, E6-2  Dirac electrons in a graphene quasicrystal file
485 2019-10-25 15:00  #1323, E6-2  Physics Seminar file
484 2019-09-18 16:00  #1323, E6-2  Exploring Synthetic Quantum Matter in Superconducting Circuits file
483 2018-10-15 16:00  #1323, E6-2  Universal properties of macroscopic current-carrying systems file