Periodic Function Of Magnetic Flux Research Articles

Transport through a quantum dot coupled to two Majorana bound states

We investigate electron transport inside a ring system composed of a quantum dot (QD) coupled to two Majorana bound states confined at the ends of a one-dimensional topological superconductor nanowire. By tuning the magnetic flux threading through the ring, the model system we consider can be switched into states with or without zero-energy modes when the nanowire is in its topological phase. We find that the Fano profile in the conductance spectrum due to the interference between bound and continuum states exhibits markedly different features for these two different situations, which consequently can be used to detect the Majorana zero-energy mode. Most interestingly, as a periodic function of magnetic flux, the conductance shows $2\pi$ periodicity when the two Majorana bound states are nonoverlapping (as in an infinitely long nanowire) but displays $4\pi$ periodicity when the overlapping becomes nonzero (as in a finite length nanowire). We map the model system into a QD--Kitaev ring in the Majorana fermion representation and affirm these different characteristics by checking the energy spectrum.

Magnetic Properties of Toroidal Carbon Nanotubes

Persistent currents in thin toroidal carbon nanotubes (TCN's) are linearly periodic functions of magnetic flux (φ) with a period φ 0 ( h c / e ). This result is a manifestation of the Aharonov-Bohm (AB) effect. They depend on the toroid structure (such as curvature, radius, and height), the temperature, and the Zeeman effect. The curvature effect due to the misorientation of π-electron orbitals affects the electronic states, and thus the persistent current. Consequently, most of armchair-zigzag TCN's exhibit diamagnetism. The current amplitude is inversely proportional to the toroid radius. A temperature increase significantly reduces the persistent current, while the periodical AB oscillation remains unchanged. Measurements of the persistent currents could be used to verify the predicted electronic states and the AB effect.

Observation of thermal electromotive force oscillations versus magnetic vector potential field in superconducting loop with two Josephson SNS junctions

Superconducting loop with two Josephson SNS junction was investigated. The junctions were biased by a heat flow. A voltage across the junctions was observed when the heat flow exceeded the critical value. This critical heat flow was a periodical function of magnetic flux in the loop. The period and the magnitude of modulation of this curve coincide with the parameters of the dependence of critical current through the same sample upon the magnetic flux in the absence of the heat flow.