Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 10: Topology: Majorana Physics I

TT 10.4: Talk

Monday, March 18, 2024, 15:45–16:00, H 2053

Braiding of Majorana box qubits in open quantum systems — •Kunmin Wu, Sadeq S. Kadijani, Johan Ekström, and Thomas Schmidt — Department of Physics and Materials Science, University of Luxembourg, 1511 Luxembourg, Luxembourg

We propose a braiding protocol in an open quantum system consisting of three coupled Majorana boxes harboring Majorana bound states (MBSs). Each MBS is coupled to a quantum dot placed in a Markovian bosonic bath. In the limit of weak coupling, the dissipation in the Majorana sector will be governed by a master equation of Lindblad form. The existence of a dark state subspace makes it possible to engineer nontrivial steady states by controlling the tunnel coupling between quantum dots and MBSs. Since braiding requires a degenerate ground state subspace with a given fermionic parity, we find that at least three Majorana boxes are needed. We start with a dark state stabilization protocol and subsequently propose a device geometry which allows the implementation of a braiding protocol. In this braiding process, the tunnel couplings are changed adiabatically and periodically, forcing the steady state to undergo a rotation on the Bloch sphere with a nontrivial winding number. Our proposal provides a template for performing braiding operations within decoherence-free subspaces in a fermionic system.

Keywords: Braiding; Topology by dissipation; Majorana bound states; Open quantum systems; The Lindblad equation