Josephson junction with two superconducting current components
- PDF / 756,126 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 70 Downloads / 197 Views
DISORDER, AND PHASE TRANSITION IN CONDENSED SYSTEM
Josephson Junction with Two Superconducting Current Components K. V. Kulikova,b,*, R. Davudc, E. P. Nakhmedovd,e, and Yu. M. Shukrinova,b a Bogoliubov
Laboratory for Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia b State University “Dubna,” Dubna, Moscow oblast, 141980 Russia c University of Cairo, Cairo, Egypt d Baku Branch, Moscow State University, Baku, AZ1144 Azerbaijan e Institute of Physics, National Academy of Sciences of Azerbaijan, Baku, AZ1143 Azerbaijan *e-mail: [email protected] Received February 16, 2017
Abstract—The properties of a Josephson junction with the 2π- and 4π-periodic superconducting current component have been analyzed. In the range of low voltages, such a junction exhibits the 4π periodicity of the phase difference for the Majorana current amplitude much smaller than the Josephson current, which makes it possible to observe Josephson current oscillations with a fractional period for small dissipation β < 1 in the hysteresis region. The effect the 4π-periodic Majorana current component is also manifested in a change in the sequence of steps in the ladder structure emerging on the current–voltage (I–V) characteristic of the junction. We have determined the interval of external electromagnetic radiation amplitudes, in which the manifestation of the fractional Josephson effect on the I–V characteristic is most significant. DOI: 10.1134/S1063776117070202
1. INTRODUCTION Majorana fermions (particles identical to their antiparticles, which are described by real-valued wavefunctions) have attracted enormous attention in recent years in view of their possible application as cubits in quantum computers. Several propositions were put forth on detection of such fermions in systems of condensed state [1–8]. In particular, Majorana fermions can be obtained as localized intragap states in a superconductor [4–8]. Such a state can be formed at the ends of a one-dimensional (1D) semiconductor wire with a strong spin–orbit coupling in a magnetic field under the action of the proximity effect of an s-wave superconductor [5, 6]. In such a case, both conventional 2π-periodic Josephson current and the Majorana current can flow through the junction [9, 10]. The Josephson junction (JJ) in the presence of the Majorana bound states exhibits 4π-periodic oscillations of superconducting current [11], and the current–voltage (I–V) characteristic of such a JJ demonstrates only even Shapiro steps in contrast to its trivial analogs. This property was called the fractional Josephson effect and was actively investigated in recent years in various systems, because it may serve as an experimental evidence of the formation of such fermions. Another possibility of detecting Majorana states is the measurement of the tunnel conductivity peak within the superconducting gap [12].
The results of experiments on the observation of Majorana fermions in systems of the condensed state, which have been performed earlier, are ambiguou
Data Loading...
