Aleksandr Svetogorov

Contact

Department of Physics
University of Basel
Klingelbergstrasse 82
CH-4056 Basel, Switzerland
office:4.7

email:view address

tel: +41 61 207 36 94


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 current-biased 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 current-biased topological Josephson junction
Aleksandr E. Svetogorov, Daniel Loss, and Jelena Klinovaja.
Phys. Rev. Research 2, 033448 (2020)

We study analytically an underdamped current-biased 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 single-quasiparticle 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 phase-slips 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 phase-slip amplitude is sensitive to the normal mode structure of superconducting phase oscillations in the ring (Mooij-Schön 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 phase-slip 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 phase-slip amplitude is sensitive to the normal-mode structure of superconducting phase oscillations in the ring (Mooij-Schön modes, which are all localized by the area disorder). However, we show that the modes' contribution to the disorder-induced phase-slip 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 phase-slip amplitude on the chain and show that it can be non-Gaussian for not sufficiently long chains.

5.  Non-adiabatic geometric phases and dephasing in an open quantum system
A. E. Svetogorov and Yu. Makhlin.
JETP Lett., 103(8), 535-538 (2016)

We analyze the influence of a dissipative environment on geometric phases in a quantum system subject to non-adiabatic evolution. We find dissipative contributions to the acquired phase and modification of dephasing, considering the cases of both weak short-correlated noise and slow quasi-stationary noise. Motivated by recent experiments, we find the leading non-adiabatic corrections to the results, known for the adiabatic limit.