报告题目：Conceptualizing laser-induced quantum-logic operations for nanospintronic devices 

报 告 人：  Dr. habil. Georg Lefkidis（德国凯泽斯劳滕工业大学）

报告时间：2018年8月20日（星期一），上午10:30

报告地点：美高梅mgm7991六层学术报告厅（致知楼3623-3624）

报告摘要：

Due to the rapid development of conventional computer devices, the applied semiconductor-based technologies are slowly reaching their physical limits with respect to both size and speed. Therefore, for future nanoscale functional devices it becomes more and more important to investigate alternative ideas. One promising road is to use the spin degree of freedom (spintronics) and to combine it with optical control (nano-spintronics).

In this talk I will first introduce some fundamental ideas needed for the logic functionalization of magnetic systems based on ab initio quantum many-body theory. The unitary time evolution of both extended and molecular systems allows for the description of coherent dynamics on the subpicosecond time scale. The first-principles separation of laser-induced spin and charge dynamics benefits from the strong electronic correlations in magnetic materials [1]. The Λ process represents a mechanism which allows for the rapid optical manipulation of the magnetic state of realistic molecules [2,3] bypassing slow dynamical degrees of freedom.

Based on these concepts I will then present several results, which show that the molecular spins can encode information in a variety of laser-driven, logical processes, going far beyond simple information storage. As main examples of functionalities on magnetic molecules I will address the implementation of Boolean logic (AND, OR, and XOR gates), the spin-SHIFT register, as well as the ERASE operation. Finally, I will address some new concepts such as mechanically controlled spin dynamics [4], the inclusion of the molecular rotation [5], as well as the which-path interference, in which the final state of the spin reveals the path followed during the spin-transfer process [6].

References:

       [1]   G. P. Zhang, W. Hübner, G. Lefkidis, Y. Bai, and T. F. George, Nature Physics 5, 499 (2009).

       [2]   W. Jin, F. Rupp, K. Chevalier, M. M. N. Wolf, M. Colindres Rojas, G. Lefkidis, H.-J. Krüger, R. Diller, and W.  Hübner, Phys. Rev. Lett. 109, 267209 (2012).

       [3]   D. Chaudhuri, W. Jin, G. Lefkidis, and W. Hübner, J. Chem. Phys. 143, 174303 (2015).

       [4]   C. Li, J. Liu, S. Zhang, G. Lefkidis, and W. Hübner, Carbon 87, 153 (2015).

       [5]   W. Jin, D. Chaudhuri, C. Li, G. Lefkidis, and W. Hübner, J. Supercond. Nov. Magn 30, 801 (2017).

       [6]   D. Chaudhuri, G. Lefkidis, and W. Hübner, Phys. Rev. B 96, 184413 (2017).

报告人简介：

Dr. habl. Georgios Lefkidis received his M.S degree and doctoral degree in Aristotle University Thessaloniki in 1995 and 2002, respectively. From 2003, he worked in Kaiserslautern University of Technology as a Post-doctoral researcher for four years. Currently he is a tenured lecturer with a Habilitation title in TU Kaiserslautern. His main research fields are electronic ab-initio theory of magneto-optics, laser-induced spin and charge dynamics, quantum thermodynamics, and logic functionalization of magnetic nanostructures for logic units and spintronics devices. Till now he has contributed 57 peer reviewed publications (PRL, Nature Physics, PRB et al.), 1 book chapter, and 35 invited talks. Also, he is a referee for several journals (e.g., American Physical Society and Physica Status Solidi).

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