News

New paper in Nature Communications

A recent study from Ádám Gali’s research group, published in Nature Communications, has proven that the kinetics of defect complex formation in semiconductors may prohibit reaching thermal equilibrium. This could change defect engineering simulation strategies for next generation quantum computing and other applications. From the research group, spread accross at the Wigner Research Centre for Physics and the BME Department of Atomic Physics, the BME co-authors of the publication are research associate Péter Udvarhely and professor Ádám Gali. 
 
Peter Deák, Péter Udvarhelyi, Gergő Thiering, and Adam Gali

 
Point defects in semiconductors and insulators play a pivotal role in electronic, photovoltaic and optical devices. Recently, point defects in solids have emerged as main actors in quantum technology hardware elements, where the tight control of their location is of utmost importance [1]. With today's fabrication techniques, point defects can be deterministically placed into the host material, even those that do not form in nature. The implantation and irradiation techniques revolutionized materials science and industrial sectors relying on it. However, irradiation techniques often introduce mobile defects beside the target quantum hardware defects that can combine with each other and form stable complex configurations. Understanding the atomistic processes behind the formation and the stability of the target defect and parasitic complexes paves the way to realize reliable devices. Furthermore, the urgent quest to find novel solutions, e.g., seeking point defects for given functionalities, for the emerging technologies calls for atomistic simulation techniques that have high predictive power and can guide the research and development directions [2,3]. Recent developments in search algorithms and the increasing computation power have directed the computational discovery of target point defects to the application of machine learning techniques. The vast majority of point defects are complexes that may exist in various configurations, and current machine learning algorithms are conditioned to find the energetically most stable defects configuration for the given applications. It is a common assumption that the most stable defect complexes will form, i.e., the thermal equilibrium of the defect complex configurations can be eventually reached.
 
Ádám Gali’s group has demonstrated by means of accurate atomistic simulations that the kinetics of the formation of defect complex configurations can prohibit to reach the thermal equilibrium [4]. In particular, this effect has been exemplified on a key defect complex in silicon which can be a basic unit for future quantum communication and quantum computation devices. The results imply that the machine learning techniques conditioned to search for thermal equilibrium defect complexes would overlook a key candidate for quantum technology applications. This study may turn the attention to the importance of kinetics in the simulation of implanted or irradiated semiconductors for defect engineering.  
 
References
 
[1] Quantum guidelines for solid-state spin defects
, Gary Wolfowicz, F. Joseph Heremans, Christopher P. Anderson, Shun Kanai, Hosung Seo, Adam Gali, Giulia Galli, David D. Awschalom
, Nature Reviews Materials 6, 906 (2021).
 
[2] Ab initio theory of the nitrogen-vacancy center in diamond
, Adam Gali
, Nanophotonics 8 1907 (2019).
 
[3] Recent advances in the ab initio theory of solid-state defect qubits, 
Ádám Gali
, Nanophotonics, on-line (2023).
 
[4] The kinetics of carbon pair formation in silicon prohibits reaching thermal equilibrium
, Peter Deák, Péter Udvarhelyi, Gergő Thiering, Adam Gali
, Nature Communications 14, 361 (2023).

 

ERC Consolidator Grant for Péter Makk

The European Research Council awarded almost 2 million euros to support the nanoelectronics research of Péter Makk, associate professor of the BME Insitute of Physics. Congratulations!

 

News item in Hungarian, at bme.hu-n: https://www.bme.hu/hirek/20230131/Ismet_muegyetemi_gyoztes_Europa_legran...

 

Web page of the Momentum Research Group of Péter Makk: https://nanoelectronics.physics.bme.hu/vdWaals_intro

 

Results of the ERC Consolidator Grant 2022: https://erc.europa.eu/news-events/news/erc-2022-consolidator-grants-results

 

 

Strong spin-lattice coupling in Swedenborgites

New experimental results of an international collaboration, led by BME associate professor Sándor Bordács, has been published in Physical Review Letters. 

 

The team, consisting of Japanese, Estonian and Hungarian researchers, have observed an unusual form of spin-lattice coupling using infrared spectroscopy.  In multiferroic Swedenborgites, the lifetime of lattice vibrations (phonons) is strongly suppressed, and the phonons are scattered by the magnetic fluctuations of the disordered paramagnetic phase. According to the explanation of the authors, the orbital degrees of freedom of the transition metal electrons play a key role in the enhanced spin-lattice interaction. The results have been published in Physical Review Letters. 

 

Vilmos Kocsis, Yusuke Tokunaga, Toomas Rõõm, Urmas Nagel, Jun Fujioka, Yasujiro Taguchi, Yoshinori Tokura, and Sándor Bordács
Spin-Lattice and Magnetoelectric Couplings Enhanced by Orbital Degrees of Freedom in Polar Multiferroic Semiconductors
 

Novel semiconductors studied at BME

BME physicists embark on a new four-year project funded by the European Union, to research the physics and applications of optically active silicon nanostructures. 

 

The project, entitled ONCHIPS (On-Chip Integration of Quantum Electronics and Photonics) is led by Floris Zwanenburg, professor at the University of Twente (Netherlands), and the BME research group is led by András Pályi, associate professor at the BME Department of Theoretical Physics. Further consortium partners: Eindhoven University of Technology, TU Munich, Center de Nanosciences et de Nanotechnologies, CNRS (Paris), Single Quantum BV (Delft) and the University of Konstanz. The starting date was November 1, 2022, and a short report on the kick-off meeting is already available here
 

Web: https://www.onchips.eu/

Twitter: https://twitter.com/ONCHIPS_EU

LinkedIn: https://www.linkedin.com/in/onchips-eu-1b487624a

 

Physicis-Engineer BSc starts in September 2023

BME’s Faculty of Natural Sciences launches a new Physicist-Engineer BSc program in September 2023.

 

In response to an overwhelming demand from technology intensive R&D companies in Hungary and worldwide, BME launches a new program to train Physicist-Engineers with strong R&D potential.

 

Our program focuses on rapidly developing technological areas such as quantum and nanotechnology, data science and artificial intelligence, photonics, quantum optics and materials science, sustainable energetics, and nuclear technology. In collaboration with our industrial partners, we offer worldwide competitive, versatile knowledge in these fields to answer novel technological challenges.

 

https://fizikusmernok.bme.hu/en/

 

Prima Primissima Prize

The 2022 edition of the Prima Primissima Prize in the category `Education in Hungary' was awarded to our colleague Károly Härtlein. Congratulations!

 

 

 

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