Denis Janković

Denis Janković
University of Strasbourg | UNISTRA · UFR de physique et d'ingénierie

PhD Student


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Citations since 2017
2 Research Items
0 Citations
Graduated in condensed matter and nanophysics. Currently studying : Hyperfine interactions in lanthanide-based single molecule magnets used in Quantum Information Processing. PhD thesis under the supervision of Paul-Antoine Hervieux from IPCMS and Pr. Dr. Mario Ruben from KIT.
Additional affiliations
September 2020 - present
University of Strasbourg
  • PhD Student
  • Hyperfine Interactions in lanthanide-organic complexes for Quantum Information Processing.
February 2020 - July 2020
University of Strasbourg
  • Intern
  • Theoretical study of the hyperfine interaction in the Single Molecule Magnet Pc2Tb that can be used in Quantum Information Processing. In collaboration with Pr. Dr. Mario Ruben from KIT.
January 2019 - April 2019
University of Basel
  • Intern
  • Theoretical study and modelization of the electronic current through a double quantum dot in a Ge Nanowire that can be used as a qubit.
September 2018 - July 2020
University of Strasbourg
Field of study
  • Physics - Condensed Matter and Nanophysics


Publications (2)
An overview of my Master Internship where I tried to explain the linear hyperfine Stark Effect observed in the Pc2Tb SMM through configuration interaction, in this poster a case study of PrCl3 is presented.
This report first introduces the research topic i.e. Quantum Information Processing and the use of Single-Molecule Magnets (SMM) in this domain. It also presents the hyperfine Stark effect observed experimentally in the specific SMM case of Pc2Tb. A second part then explores a theoretical model devised to try to explain the latter effect by the me...


Question (1)
In Gaussian's output files, one can see :
Electronic spatial extent (au): <R**2>= 5374.1715
Charge= -6.0000 electrons
Dipole moment (field-independent basis, Debye):
X= 0.0005 Y= -0.0004 Z= -0.0000 Tot= 0.0006
Quadrupole moment (field-independent basis, Debye-Ang):
XX= -283.8668 YY= -283.8665 ZZ= -290.8814
XY= -0.0001 XZ= -0.0000 YZ= 0.0000
Traceless Quadrupole moment (field-independent basis, Debye-Ang):
XX= 2.3381 YY= 2.3384 ZZ= -4.6765
XY= -0.0001 XZ= -0.0000 YZ= 0.0000
Octapole moment (field-independent basis, Debye-Ang**2):
XXX= -38.6039 YYY= 10.9116 ZZZ= -0.0000 XYY= 38.6092
XXY= -10.9151 XXZ= -0.0000 XZZ= 0.0025 YZZ= -0.0021
YYZ= -0.0000 XYZ= 0.0000
Hexadecapole moment (field-independent basis, Debye-Ang**3):
XXXX= -3299.0791 YYYY= -3299.0809 ZZZZ= -3536.0818 XXXY= -0.0007
XXXZ= 0.0000 YYYX= -0.0008 YYYZ= 0.0000 ZZZX= -0.0000
ZZZY= 0.0000 XXYY= -1099.6932 XXZZ= -1203.6362 YYZZ= -1203.6302
XXYZ= 0.0000 YYXZ= -0.0000 ZZXY= -0.0019
What is this field-independent basis ?
This is the output file of a charged molecular ion, and I know that in case of a non-neutral charge distribution, the multipoles are not uniquely defined, and depend on the choice of origin, what is the choice of origin of Gaussian ?
I figured it was the basis in which the energy is independent of the electric field to the first order (a.k.a. no dipole), since there is always a choice of origin for which the dipole is zero for non-neutral charge distributions. But I am not sure.
Could anyone enlighten me ?


Projects (2)
As an extension of the well-known two-level quantum bits (qubits), multilevel systems, the so-called qudits, where d represents the dimension of the Hilbert space, have been predicted to reduce the number of iterations in quantum-computation algorithms. This has been tested experimentally in single-molecule magnets (i.e. metal-organic complex TbPc2) where multilevels are originated from the nuclear spins and the associated dipole and quadrupole hyperfine interactions (HIs) [1]. Controlling or modifying these interactions may open the way to the manipulation of the multilevel systems’ properties thus leading to improvements or elaboration of new quantum-computation algorithms. In close collaboration with experimental physicists and materials chemists from KIT we propose to establish a theoretical framework to answer this issue. This project will profit from existing local and external collaborations, both with quantum chemists, nuclear physicists and experimentalists from KIT who synthesize, characterize and manipulate single-molecule magnets. The project is structured in three main objectives: • We will explore the possibility to modify the hyperfine interactions by using a static electric field compatible with the experimental limitations; • The possibility to synthetically upscaling of a molecular Qudit permits to increase significantly the number of accessible nuclear states and therefore the computational power of the quantum device. The role played by the electronic spin making the link between the nuclear spins is under debate. In order to solve this issue we will develop a theoretical model which combines both itinerant (electronic) and localized (nuclear) magnetism and their interplay through various magnetic exchange mechanisms [2]. • For optical read-out purposes, the effect of the nuclear spin on the optical properties of lanthanide complexes will be also explored theoretically. [1] W. Wernsdorfer and M. Ruben, Adv. Mater. 31, 1806687 (2019). [2] J. Hurst, P. –A. Hervieux, and G. Manfredi, Phys. Rev. B 97, 014424 (2018); Philosophical Transactions A 375, 2092 (2017).
This project is an internship and the goal is to make some ab-initio calculations to study the nuclear effects of the central Terbium atom on the electronic structure of the said atom and then obtain the shift in energy of the hyperfine levels due to an applied external electric field. The more general use of this SMM (Single Molecule Magnet) is in QIP (Quantum Information Processing) as molecular qudit of dimension 4.