News

BME Best Teacher Award for Péter Vankó

Péter Vankó, associate professor of the Department of Physics, receives the Best Teacher Award of BME in 2019 Fall semester. Interview (in Hungarian) in the student's magazine Műhely.

 

,,Szakmai biztonság, felszabadultság, emberség''
interview (in Hungarian) with Péter Vankó
Műhely, XVIII. évfolyam, 6. szám, 2020. április 20.
http://ehk.bme.hu/muhely/20200420/megjelent-a-nbsp-xviii-evf-6-lapszam
 

The Yu-Shiba-Rusinov state

BME physicists find an unexpectedly large extension of the Yu-Shiba-Rusinov (YSR) state in a superconducting nanostructure, a result which paves the way toward topologically protected qubits. The work is published in Nature Communications, in collaboration with colleagues University of Basel.

 

Recent years have bought new quantum bit proposals, which are based on low-energy bound states in superconducting environment. These qubits would combine the properties of spin-based and superconductor-based qubits, and they are robust against noise-induced information loss. One such qubit is based on the so-called Yu-Shiba-Rusinov (YSR) state: a linear chain, engineered from such bound states, could host noise-protected quantum states. Due to the very small spatial extension of these states, making two of them interact with one another is difficult. Up to now, this was only possible by a very delicate technique, where individual ferromagnetic atoms are deposited next to each other.

 

In their new study, the MTA-BME Momentum Nanoelectronics Research Group realizated the YSR state in an alternative way: they attached an artificial atom to the superconductor's surface. This is the first time that the spatial extension of such a YSR state is measured. The measurement brought a surprising result: The size of the YSR state reaches 50-200 nanometers, which is significantly larger than the spatial extension observed in the case of real, ferromagnetic atoms. With state-of-the-art nanotechnology, artificial atoms can be routinely fabricated at such distances, which paves the way to realize YSR chains. The large extension of the YSR state has been theoretically explained in collaboration with another research group of BME’s Institute of Physics, the BME-MTA Exotic Quantum Phases Momentum Group.

 

Figure: Measurement of the spatial extension of the Yu-Shiba-Rusinov state. As an artificial atom (quantum dot, QD) is attached to a superconductor (SC), a Yu-Shiba-Rusinov state (blue) forms at the quantum dot and its surrounding in the superconductor. The YSR state is probed by measuring the current (IT) through an electrode on the left side of the superconductor. Despite the relatively large, 200 nanometer width of the superconductor, the YSR state was observed by the tunnel probe. In agreement with our calculations, the size of the YSR state increases further in a finite external magnetc field.

 
Zoltán Scherübl, Gergő Fülöp, Cătălin Paşcu Moca, Jörg Gramich, Andreas Baumgartner, Péter Makk, Tosson Elalaily, Christian Schönenberger, Jesper Nygård, Gergely Zaránd, Szabolcs Csonka
Large spatial extension of the zero-energy Yu-Shiba-Rusinov state in magnetic field
Nature Communications 11, 1834 (2020).
https://www.nature.com/articles/s41467-020-15322-9
https://arxiv.org/abs/1906.08531.

PIN code of atomic synapses revealed

Single-atom-sized wires carry the electric current in the memristors created by our colleagues in the Nanoelectronics research group. Research published in Nano Letters.

 

Tímea Nóra Török, Miklós Csontos, Péter Makk, András Halbritter
Breaking the Quantum PIN Code of Atomic Synapses
Nano Lett. 20, 1192 (2020)
https://doi.org/10.1021/acs.nanolett.9b04617

 

 

Website of the research group: http://nanoelectronics.physics.bme.hu/

Mechanically controlled pattern formation

Our colleagues in a collaboration with researchers from Bilkent University showed the formation of periodic patterns by a diffusion–precipitation reaction in a stretchable hydrogel and the control of the obtained patterns by the unprecedented and uncommon method of mechanical input. The study has been published in Advanced Materials.

 

Mohammad Morsali, Muhammad Turab Ali Khan, Rahym Ashirov, Gábor Holló, H. Tarik Baytekin, Istvan Lagzi, Bilge Baytekin
Mechanical Cntrol of Periodic Precipitation in Stretchable Gels to Retrieve Information on Elastic Deformation and for the Complex Patterning of Matter
Advanced Materials (2018 impact factor: 25.809)
doi:10.1002/adma.201905779

Novobátzky Prize for Balázs Pozsgai

Our colleague was awarded the Novobátzky Prize of the Eötvös Loránd Physical Society for his pioneering contributions in the theoretical description of the non-equilibrium dynamics of integrable quantum spin chains.

 

Currently, Balázs is a member of the MTA-BME Quantum Dynamics and Correlations Research Group, based at BME Department of Theoretical Physics. Previously, he was a member of the "Lendület Statistical Field Theory Research Group" at the same department, where he has been the recipient of the MTA Premium Postdoctoral Grant as well as the MTA Bolyai and Bolyai+ Grants.

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