21 research outputs found
Out-of-Equilibrium Admittance of Single Electron Box Under Strong Coulomb Blockade
We study admittance and energy dissipation in an out-of-equlibrium single
electron box. The system consists of a small metallic island coupled to a
massive reservoir via single tunneling junction. The potential of electrons in
the island is controlled by an additional gate electrode. The energy
dissipation is caused by an AC gate voltage. The case of a strong Coulomb
blockade is considered. We focus on the regime when electron coherence can be
neglected but quantum fluctuations of charge are strong due to Coulomb
interaction. We obtain the admittance under the specified conditions. It turns
out that the energy dissipation rate can be expressed via charge relaxation
resistance and renormalized gate capacitance even out of equilibrium. We
suggest the admittance as a tool for a measurement of the bosonic distribution
corresponding collective excitations in the system
Zero-voltage conductance peak from weak antilocalization in a Majorana nanowire
We show that weak antilocalization by disorder competes with resonant Andreev
reflection from a Majorana zero-mode to produce a zero-voltage conductance peak
of order e^2/h in a superconducting nanowire. The phase conjugation needed for
quantum interference to survive a disorder average is provided by particle-hole
symmetry - in the absence of time-reversal symmetry and without requiring a
topologically nontrivial phase. We identify methods to distinguish the Majorana
resonance from the weak antilocalization effect.Comment: 13 pages, 8 figures. Addendum, February 2014: Appendix B shows
results for weak antilocalization in the circular ensemble. (This appendix is
not in the published version.
Majorana qubits in a topological insulator nanoribbon architecture
We describe designs for the realization of topological Majorana qubits in terms of proximitized topological insulator nanoribbons pierced by a uniform axial magnetic field. This platform holds promise for particularly robust Majorana bound states, with easily manipulable interstate couplings. We propose proof-of-principle experiments for initializing, manipulating, and reading out Majorana box qubits defined in floating devices dominated by charging effects. We argue that the platform offers design advantages which make it particularly suitable for extension to qubit network structures realizing a Majorana surface code