Aleksandr Svetogorov
ContactDepartment of PhysicsUniversity of Basel Klingelbergstrasse 82 CH4056 Basel, Switzerland

Short CV
2019  Present  Postdoc, University of Basel, Switzerland with Prof. Jelena Klinovaja 
2016  2019  Ph.D. at the University Grenoble Alpes with Dr. Denis Basko 
2014  2016  Master in Physics at the Moscow Institute of Physics and Technology with Prof. Yuriy Makhlin 
2010  2014  Bachelor in Physics at the Moscow Institute of Physics and Technology with Prof. Yuriy Makhlin 
Publications
Show all abstracts.1.  Insulating regime of an underdamped currentbiased Josephson junction supporting Z 3 and Z 4 parafermions 
Aleksandr Svetogorov, Daniel Loss, and Jelena Klinovaja. Phys. Rev. B 103, L180505 (2021)  
2.  Critical current for an insulating regime of an underdamped currentbiased topological Josephson junction 
Aleksandr E. Svetogorov, Daniel Loss, and Jelena Klinovaja. Phys. Rev. Research 2, 033448 (2020)
We study analytically an underdamped currentbiased topological Josephson junction. First, we consider a
simplified model at zero temperature, where the parity of the nonlocal fermionic state formed by Majorana
bound states (MBSs) localized on the junction is fixed, and show that a transition from insulating to conducting
state in this case is governed by singlequasiparticle tunneling rather than by Cooper pair tunneling, in contrast to
a nontopological Josephson junction. This results in a significantly lower critical current for the transition from
insulating to conducting state. We propose that if the length of the system is finite, the transition from insulating
to conducting state occurs at exponentially higher bias current due to hybridization of the states with different
parities as a result of the overlap of MBSs localized on the junction and at the edges of the topological nanowire
forming the junction. Finally, we discuss how the appearance of MBSs can be established experimentally by
measuring the critical current for an insulating regime at different values of the applied magnetic field.
 
3.  Theory of coherent quantum phaseslips in Josephson junction chains with periodic spatial modulations 
Aleksandr E. Svetogorov, Masahiko Taguchi, Yasuhiro Tokura, Denis M. Basko, and Frank W. J. Hekking. Phys. Rev. B 97, 104514 (2019)
We study coherent quantum phase slips which lift the ground state degeneracy in a Josephson junction ring, pierced by a magnetic flux of the magnitude equal to half of a flux quantum. The quantum phaseslip amplitude is sensitive to the normal mode structure of superconducting phase oscillations in the ring (MooijSchön modes). These, in turn, are affected by spatial inhomogeneities in the ring. We analyze the case of weak periodic modulations of the system parameters and calculate the corresponding modification of the quantum phaseslip amplitude.
 
4.  Effect of disorder on coherent quantum phase slips in Josephson junction chains 
A. E. Svetogorov and D. M. Basko. Phys. Rev. B 98, 054513 (2019)
We study coherent quantum phase slips in a Josephson junction chain, including two types of quenched disorder: random spatial modulation of the junction areas and random induced background charges. Usually, the quantum phaseslip amplitude is sensitive to the normalmode structure of superconducting phase oscillations in the ring (MooijSchön modes, which are all localized by the area disorder). However, we show that the modes' contribution to the disorderinduced phaseslip action fluctuations is small, and the fluctuations of the action on different junctions are mainly determined by the local junction parameters. We study the statistics of the total quantum phaseslip amplitude on the chain and show that it can be nonGaussian for not sufficiently long chains.
 
5.  Nonadiabatic geometric phases and dephasing in an open quantum system 
A. E. Svetogorov and Yu. Makhlin. JETP Lett., 103(8), 535538 (2016)
We analyze the influence of a dissipative environment on geometric phases in a quantum system subject to nonadiabatic evolution. We find dissipative contributions to the acquired phase and modification of dephasing, considering the cases of both weak shortcorrelated noise and slow quasistationary noise. Motivated by recent experiments, we find the leading nonadiabatic corrections to the results, known for the adiabatic limit.
