Speaker: Manuel del Pino
Affiliation: Department of Physics and Astronomy, Rutgers
Date: Tuesday, 19 January 2016 at 14:30
Location: Seminar Room, Serrano 121 (CFMAC)
The search for Majorana bound states in solid-state physics has been limited to materials which display a gap in their bulk spectrum. We will show that such unpaired states appear in certain quasi-one-dimensional Josephson junctions arrays with gapless bulk excitations [1]. The bulk modes mediate a coupling between Majorana bound states via the Ruderman-Kittel-Yosida-Kasuya mechanism. As a consequence, the lowest energy doublet acquires a finite energy difference. For realistic set of parameters this energy splitting remains much smaller than the energy of the bulk eigenstates even for short chains of length L~10. In this talk, we first explain the JJA system and how to model it with an Ising-like Hamiltonian. Then, a qualitative argument is employed to obtain the low-energy effective theory using unpaired Majorana modes. We will show numerical results which confirm the validity of this effective theory and discuss problems that may arise in the experimental realization of our proposal.
[1] M. Pino, A. M. Tsvelik, and L. B. Ioffe, Phys. Rev. Lett. 115, 197001 (2015)