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Title: Kondo physics from quasiparticle poisoning in Majorana devices

Here, we present a theoretical analysis of quasiparticle poisoning in Coulomb-blockaded Majorana fermion systems tunnel-coupled to normal-conducting leads. Taking into account finite-energy quasiparticles, we derive the effective low-energy theory and present a renormalization group analysis. We find qualitatively new effects when a quasiparticle state with very low energy is localized near a tunnel contact. For M = 2 attached leads, such “dangerous” quasiparticle poisoning processes cause a spin S = 1/2 single-channel Kondo effect, which can be detected through a characteristic zero-bias anomaly conductance peak in all Coulomb blockade valleys. For more than two attached leads, the topological Kondo effect of the unpoisoned system becomes unstable. A strong-coupling bosonization analysis indicates that at low energy the poisoned lead is effectively decoupled and hence, for M > 3, the topological Kondo fixed point re-emerges, though now it involves only M–1 leads. As a consequence, for M = 3, the low-energy fixed point becomes trivial corresponding to decoupled leads.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [1]
  1. Heinrich-Heine-Univ., Dusseldorg (Germany)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Heinrich-Heine-Univ., Dusseldorg (Germany); Univ. Grenoble Alpes, Grenoble (France); CEA, INAC-SPSMS, Grenoble (France)
Publication Date:
OSTI Identifier:
1255721
Report Number(s):
BNL--112202-2016-JA
Journal ID: ISSN 2469-9950; PRBMDO; R&D Project: PO015; KC0202030
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 93; Journal Issue: 10; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY