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Abstract |
Long-lived fluxon excitations can be trapped inside a superinductor ring, which can be realized with a long array of Josephson junctions, one of which offers the input/ output path for the magnetic flux [1]. The superinductor ring can be separated into smaller loops by a periodic sequence of Josephson junctions in the quantum regime, thereby allowing fluxons to tunnel between neighboring loops. This model is dual to that of two-leg ladder bosons, which have a rich phase diagram depending on flux and density [2]. By tuning the Josephson coupling, and implicitly the tunneling probability amplitude of fluxons, a wide class of 1D tight-binding lattice models may be implemented and populated with a stable number of fluxons. In this context, fluxons are lattice bosons with repulsive interactions. We illustrate this quantum simulation platform by discussing the Su-Schrieffer-Heeger model in the 1-fluxon subspace, which hosts a symmetry protected topological phase with fractionally charged bound states at the edges [3]. This pair of localized edge states could be used to implement a superconducting qubit increasingly decoupled from decoherence mechanisms.
[1] N. A. Masluk, I. M. Pop, A. Kamal, Z. K. Minev, and M. H. Devoret, Phys. Rev. Lett. 109, 137002 (2012).
[2] E. Orignac and T. Giamarchi, Phys. Rev. B 64, 144515 (2001); A. Petrescu and K. Le Hur, Phys. Rev. Lett. 111, 150601 (2013); M. Piraud, F. Heidrich-Meisner, I. P. McCulloch, S. Greschner, T. Vekua, and U. Schollwllwock, Phys. Rev. B 91, 140406 (2015); A. Petrescu, M. Piraud, G. Roux, I. P. McCulloch, and K. Le Hur, Phys. Rev. B 96, 014524 (2017).
[3] R. Jackiw and C. Rebbi, Phys. Rev. D 13, 3398 (1976); W. P. Su, J. R. Schrie-er, and A. J. Heeger, Phys. Rev. Lett. 42, 1698 (1979).
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