Stability of Floquet Majorana Box Qubits

In one-dimensional topological superconductors driven periodically with the frequency omega, two types of topological edge modes may appear, the well-known Majorana zero mode and a Floquet Majorana mode located at the quasienergy PLANCK CONSTANT OVER TWO PI omega/2. We investigate two Josephson-coupled topological quantum wires in the presence of Coulomb interactions, forming a so-called Majorana box qubit. An oscillating gate voltage can induce Floquet Majorana modes in both wires. This allows for the encoding of three qubits in a sector with fixed electron parity. If such a system is prepared by increasing the amplitude of oscillations adiabatically, it is inherently unstable as interactions resonantly create quasiparticles. This can be avoided by using instead a protocol where the oscillation frequency is increased slowly. In this case, one can find a parameter regime where the system remains stable.

Automated summary

Investigated two Josephson-coupled topological quantum wires with Coulomb interactions, inducing Floquet Majorana modes through oscillating gate voltage, enabling encoding of three qubits in a sector with fixed electron parity. Avoided system instability by gradually increasing oscillation frequency.