Half-integer charge injection by a Josephson junction without excess noise

Abstract

A Josephson junction in a topological superconductor can inject a charge e/2 into a normal-metal contact, carried by chiral Majorana edge modes. Here we address the question whether this half-integer charge is a sharp observable, without quantum fluctuations. Because the Majorana modes are gapless, they support charge fluctuations in equilibrium at zero temperature. But we find that the excess noise introduced out of equilibrium by the e/2 charge transfer vanishes. We discuss a strategy to reduce the equilibrium fluctuations, by means of a heavy-tailed time-dependent detection efficiency, to achieve a nearly noiseless half-integer charge transfer.

11 pages, 4 figures; V2: added an appendix on the alternative calculation via bosonisation

References in corpus (8)

• Electrically detected interferometry of Majorana fermions in a topological insulator
• Electron fractionalization in two-dimensional graphenelike structures
• Minimal excitation states of electrons in one-dimensional wires
• Electron quantum optics in quantum Hall edge channels
• A note on the Full Counting Statistics of paired fermions
• Scattering Approach to Counting Statistics in Quantum Pumps
• Allowed charge transfers between coherent conductors driven by a time-dependent scatterer
• Fredholm determinants and the statistics of charge transport