Seminar DON presented by Denis JANKOVIC

Dr. Denis JANKOVIC – Theory of Quantum-Coherence of Spin-qubits on Surfaces ; Center for Quantum Nanoscience ; Institute of Basic Science & Ewha Womans University (Seoul, South Korea)

Dr. Denis Jankovic uses quantum optimal control to push surface-based qubits/qudits—single-molecule magnets, holmium single-atom magnets (nuclear-spin qudits with an exceptionally small Landau–Zener gap), and STM-addressed spins—showing how tailored pulses and realistic modeling unlock scalable operations.

Contact: Giovanni Manfredi (giovanni.manfredi@ipcms.unistra.fr)

Abstract

 

Seminar presented by Dr. Salambô Dago

Speaker : Dr. Salambô Dago

Vienna Center for Quantum Science and Technology (VCQ) University of Vienna)

Résumé : Feedback control provides a versatile tool for manipulating nanoscale systems dominated by thermal or quantum fluctuations. We present two experimental applications of feedback to explore non equilibrium physics. First, we demonstrate how a feedback loop can create a virtual double potential for an underdamped micromechanical oscillator, enabling a 1-bit memory platform to perform fast logical operations and investigate the energetic cost of information processing [1-5].
Second, we introduce FLIP (Feedback Stabilization on an Inverted Potential), a novel feedback scheme combining Kalman filtering with optical trapping to achieve quantum control [6] and ground-state cooling of levitated nanospheres. This approach allows stable levitation in a double-well configuration while mitigating absorption, opening new routes for optical manipulation at the quantum limit [7].

[1] S. Dago, J. Pereda, S. Ciliberto, and L. Bellon,. JSTAT, 2022(5):053209, (2022).
[2] S. Dago, J. Pereda, N. Barros, S. Ciliberto, and L. Bellon, Phys. Rev. Lett., 126:170601 (2021).
[3] S. Dago, and L. Bellon, Phys. Rev. Lett., 128, 070604 (2022)
[4] S. Dago, L. Bellon, Phys. Rev. E 108, L022101 (2023)
[5] S. Dago, S. Ciliberto and L. Bellon, PNAS Vol.120, No 39
[6] L. Magrini, P. Rosenzweig, C. Bach, A. Deutschmann-Olek, S. G. Hofer, S. Hong, N. Kiesel, A. Kugi
Nature 595, 373 (2021).
[7] S. Dago, J. Rieser, M. Ciampini, V. Mlynar, M. Aspelmeyer, A. Deutschmann-Olek et N. Kiesel Optics
Express 32, 45133-45141 (2024

Contact : Cyriaque Genet
genet@unistra.fr / 03 68 85 51 96

DMO Seminar presented by Prof. PACHAIYAPPAN RAJAMALLI

Speaker : Prof Pachaiyappan RAJAMALLI

Abstract : Thermally activated delayed fluorescence (TADF) emitters have garnered much attention due to 100% exciton utilization and toxic metal-free design. However, most of the TADF emitters experience a concentration-quenching effect due to which emitting layers are dispersed into the host matrix. There is an urgent need to develop emitters that give the same performance and emission wavelength irrespective of the concentration of emitters. Herein, two TADF emitters (2BPy-pTC and 2BPy-oTC) are designed and synthesized. For both emitters, the nature and energetics of the lowest excited singlet and triplet together with the extent of through-bond exciton transfer (TBET) and through-space exciton transfer (TSET) are unveiled using reliable quantum-chemical calculations. While 2BPy-pTC exhibits pre-dominantly TBET, a greater extent of TSET is found in 2BPy-oTC. 2BPy-pTC displays blue color with emission maxima at 469 nm while 2BPy-oTC exhibits green color with emission maxima at 509 nm in toluene. Both emitters show a low singlet-triplet energy gap (ΔEST) of 0.20 eV for 2BPy-pTC and 0.01 eV for 2BPy-oTC and a delayed lifetime of 147.4 μs for 2BPy-pTC and 7.4 μs for 2BPy-oTC. 2BPy-pTC shows EQEmax of 12% with an Electroluminescence (EL) peak at 467 nm while 2BPy-oTC shows EQEmax of 24% with EL maxima of 500 nm. In the case of 2BPy-pTC, upon increasing the concentration of the dopant from 5 wt% to 100 wt%, the EL peak experiences a bathochromic shift from 467 to 495 nm and EQEmax drops from 12% to 5.5%. On the other hand, 2BPy-oTC maintains EQEmax of ~24% and EL maxima of 500 nm while increasing the concentration of dopant from 5 wt% to 100 wt%. Hence, 2BPy-oTC acts as a universal dopant for both doped and non-doped OLEDs through which the tedious co-deposition process can be avoided.

References

[1] Chem. Commun., 2024,60, 9234.

[2] J. Mater. Chem. C, 2023, 11, 16368.

[4] ACS Appl. Electron. Mater, 2023, 5, 4959. [5] Adv. Optical Mater.2024, 2402820.

DSI Seminar presented by Gracie Chaney

Gracie Chaney (Sorbonne Université, Laboratoire de Chimie Theorique PARIS)

Abstract : Although ab initio molecular dynamics (AIMD) can predict the chemical reactions in materials with quantum accuracy, it suffers from computational inefficiency that constrains simulations in size (<1000 atoms) and time (<100 ps). Machine learned interatomic potentials (MLIPs) bridge the gap between quantum accuracy and classical efficiency by learning the potential energy surface of the system from the AIMD data and using it as the force field in classical molecular dynamics (CMD) simulations. In this presentation, I will feature two very different systems for which I have used MLIPS. The first is the interface of a solid-state battery consisting of a Li-metal anode and an argyrodyte Li6PS5Cl solid-state electrolyte. By using a moment-tensor potential scheme we were able to generate an MLIP that accurately predicted the short- and long-term growth of the solid-electrolyte interphase region initiated by reduction of the electrolyte by the anodic Li [2]. The second system consists of a dense liquid of NH3/H2O/CH4 subjected to extreme temperatures (3000 K) and pressures (22-69GPa). In this case, we used an equivariant neural network potential [3] trained on an even distribution of NH3/H2O/CH4 structures of various NH3 amounts (4, 8, and 12). Both the AIMD and MLIP+MD simulations showed that increasing pressure at high temperature induces water ionization and begins a process involving the formation of transient CH5+ molecules and highly reactive carbocations that drive hydrocarbon chain growth toward nanodiamonds. Such results could be useful for understanding the dynamics within icy giant planets, such as Uranus and Neptune.

[1] Ivan S Novikov et al. 2021 Mach. Learn.: Sci. Technol. 2, 025002

[2] Gracie Chaney et al. 2024 ACS Appl. Mater. Interfaces 16, 19, 24624–24630

[3] Musaelian, A., Batzner, S., Johansson, A. et al. (2023) Nat Commun 14, 579

Contactc : Hervé Bulou (0388107095 – herve.bulou@ipcms.unistra.fr) et Christine Goyhenex (0388107097 – christine.goyhenex@ipcms.unistra.fr)

Seminar : Joël Bellessa

Joël Bellessa (Institut Lumière Matière, CNRS-Université Lyon 1)

The proximity of nanostructures or metallic films to semiconductors significantly affects their properties, particularly optical ones. First, we will describe the strong light–matter coupling between organic semiconductors (J-aggregate molecules) and a surface plasmon mode. We will specifically discuss the collective effects between different molecules induced by light–matter hybridization. By structuring the material on the scale of the coherent mode extension, we will show that it is possible to create an original type of active polaritonic metasurface, as well as to achieve efficient energy transfer. In a second part, we will address structures composed of metals and inorganic semiconductors (gallium arsenide). The potential applications of these structures for the realization of surface lasers will be described.