Quantum computers promise to revolutionize computing by performing certain tasks exponentially faster than classical computers. Quantum bits, or qubits, are the building blocks of quantum computers but suffer from decoherence due to unwanted couplings to environment. In topological quantum computation, the quantum information is stored in non-local topological degrees of freedom with the promise of longer coherence times. Most topological qubit proposals are based on topological superconducting "islands" that have a significant charging energy, protecting the qubit from detrimental quasiparticle poisoning. In this talk I will focus on a more primitive device, the “Majorana charge qubit”. This non-topological qubit consists of two Coulomb-blockaded islands hosting Majorana zero modes. The frequency of the qubit is determined by coherent single electron tunneling between the two islands originating from the hybridization energy E_M of two Majorana zero modes. I will discuss the sequential tunneling current through the qubit device coupled to normal metal leads. The current-voltage characteristics can be used to probe E_M and forms the basis for time-domain Rabi measurements. I will also discuss the decoherence mechanisms of the qubit focusing on intrinsic dephasing due to tunneling of above-gap quasiparticles. The Majorana charge qubit serves as an important step towards a full-fledged topological qubit.
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