Haidekker Galambos Tamás
ContactDepartment of PhysicsUniversity of Basel Klingelbergstrasse 82 CH4056 Basel, Switzerland

Short CV
2017present: Ph.D. student in the Condensed Matter Theory & Quantum Computing group at the University of Basel, supervisors: Prof. Klinovaja and Prof. Loss2017: Diplome d´Ingénieur des Arts et Manufactures (Ecole Centrale Paris, ECP)
2016/2017: Master's Thesis at BME: Development of Path Integral Monte Carlo simulations in magnetic field, Supervisor: Dr. Tőke Csaba
20152017: M.Sc. in Physics at the Budapest University of Technology and Economics (BME), Budapest, Hungary
2014/2015: Bachelor's Thesis at BME: A simple application of the Path Integral Monte Carlo method, Supervisor: Dr. Tőke Csaba
20122014: Double Degree Programme (T.I.M.E.) at Ecole Centrale Paris (ECP), Paris, France
20102015: B.Sc. in Physics at the Budapest University of Technology and Economics (BME), Budapest, Hungary
Publications
Show all abstracts.1.  Crossed Andreev reflection in spinpolarized chiral edge states due to the Meissner effect 
Tamás Haidekker Galambos, Flavio Ronetti, Bence Hetényi, Daniel Loss, and Jelena Klinovaja. Phys. Rev. B 106, 075410 (2022); arXiv:2203.05894.
We consider a hybrid quantum Hallsuperconductor system, where a superconducting finger with oblique profile is wedged into a twodimensional electron gas in the presence of a perpendicular magnetic field, as considered by Lee et al., Nat. Phys. 13, 693 (2017). The electron gas is in the quantum Hall regime at filling factor
ν=1. Due to the Meissner effect, the perpendicular magnetic field close to the quantum Hallsuperconductor boundary is distorted and gives rise to an inplane component of the magnetic field. This component enables nonlocal crossed Andreev reflection between the spinpolarized chiral edge states running on opposite sides of the superconducting finger, thus opening a gap in the spectrum of the edge states without the need of spinorbit interaction or nontrivial magnetic textures. We compute numerically the transport properties of this setup and show that a negative resistance exists as a consequence of nonlocal Andreev processes. We also obtain numerically the zeroenergy local density of states, which systematically shows peaks stable to disorder. The latter result is compatible with the emergence of Majorana bound states.
 
2.  Superconducting Quantum Interference in Edge State Josephson Junctions 
Tamás Haidekker Galambos, Silas Hoffman, Patrik Recher, Jelena Klinovaja, and Daniel Loss. Phys. Rev. Lett. 125, 157701 (2020); arXiv:2004.01733.
We study superconducting quantum interference in a Josephson junction linked via edge states in twodimensional (2D) insulators. We consider two scenarios in which the 2D insulator is either a topological or a trivial insulator supporting onedimensional (1D) helical or nonhelical edge states, respectively. In equilibrium, we find that the qualitative dependence of critical supercurrent on the flux through the junction is insensitive to the helical nature of the mediating states and can, therefore, not be used to verify the topological features of the underlying insulator. However, upon applying a finite voltage bias smaller than the superconducting gap to a relatively long junction, the finitefrequency interference pattern in the nonequilibrium transport current is qualitatively different for helical edge states as compared to nonhelical ones.
 
3.  Pathintegral Monte Carlo study of electronic states in quantum dots in an external magnetic field 
Csaba Tőke and Tamás Haidekker Galambos. Phys. Rev. B 100, 165136 (2019); arXiv:1905.07802.
We explore the correlated electron states in harmonically confined fewelectron quantum dots in an external magnetic field by the pathintegral Monte Carlo method for a wide range of the field and the Coulomb interaction strength. Using the phase structure of a preceding unrestricted HartreeFock calculation for phase fixing, we find a rich variety of correlated states, often completely different from the prediction of meanfield theory. These are finite temperature results, but sometimes the correlations saturate with decreasing temperature, providing insight into the groundstate properties.
 
4.  Pathintegral Monte Carlo simulation of timereversal noninvariant bulk systems with a case study of rotating Yukawa gases 
Tamás Haidekker Galambos and Csaba Tőke. Phys. Rev. E 97, 022140 (2018); arXiv:1702.01710.
We elaborate on the methodology to simulate bulk systems in the absence of timereversal symmetry by the phasefixed pathintegral Monte Carlo method under (possibly twisted) periodic boundary conditions. Such systems include twodimensional electrons in the quantum Hall regime and rotating ultracold Bose and Fermi gases; timereversal symmetry is broken by an external magnetic field and the Coriolis force, respectively. We provide closedform expressions in terms of Jacobi elliptic functions for the thermal density matrix (or the Euclidean propagator) of a single particle on a flat torus under very general conditions. We then modify the multislice sampling method in order to sample paths by the magnitude of the complexvalued thermal density matrix. Finally, we demonstrate that these inventions let us study the vortex melting process of a twodimensional Yukawa gas in terms of the de Boer interaction strength parameter, temperature, and rotation (Coriolis force). The bosonic case is relevant to ultracold FermiFermi mixtures of widely different masses under rotation.
