Interdiszciplináris fluktuáció és zajproblémák technológiai alkalmazásokkal: nanostrukturák, sztochasztikus rezonancia, szenzorok és más releváns alkalmazások = Interdisciplinary scientific problems of noise and fluctuations with technological applications: nanostructures, stochastic resonance, sensors and other relevant applications

A kutatások során numerikus szimulációkkal és mérésekkel is megmutattuk, hogy a sztochasztikus rezonancia segítségével jelentős jel/zaj viszony erősítés érhető el igen általános feltételek és bemenő jelek esetére. Az 1/f zaj időbeli szerkezetének vizsgálatához DSP alapú jelgenerátort fejlesztettünk ki, és empirikus formulát adtunk meg a zaj szintmetszési statisztikájának leírására. Neurokardiológiai kutatási erdeményeink közé tartozik a vérnyomásjelek spektrális analízisének új, artefaktumokra sokkal kevésbé érzékeny módszerének bevezetése és DSP alapú mérőműszerek kifejlesztése. Félvezető polimerek termikus és elektromos tulajdonságainak kutatásába, nanotechnológiai alapú kémiai szenzorok vizsgálatába is bekapcsolódtunk. Digitális műszereket fejlesztettünk ki impulzuslézerek késleltetésének sztochasztikus szabályozására és egy AFM mérőműszer precízebb vezérléséhez is. A virtuális méréstechnikában szerzett jártasságunkra alapozva szakmódszertani kutatásként demonstrációs kísérleteket fejlesztettünk ki. A kutatási eredmények publikációi: 3 könyv illetve konferenciakiadvány szerkesztése; 6 nemzetközi és 2 hazai meghívott előadás, 8 nemzetközi és 1 hazai cikk, 10 nemzetközi és 1 hazai konferenciaelőadás. | On the basis of numerical simulations and measurements we have shown that high signal-to-noise ratio gain can be obtained in systems showing stochastic resonance for quite general conditions and various signals. The time structure of 1/f type noises has been explored by universal DSP based noise generator developed by our group. We have introduced an empirical expression for the level-crossing statistics of 1/f noises. We have shown a new method for the spectral analysis of blood pressure which is much more straightforward and insensitive to artifacts than the commonly used resampling method. DSP based instruments supporting neurocardiological data acquisition have also been developed. We have started collaborations for the research of the thermal and electrical properties of semiconductor polymers, and nanotechnology-based chemical sensors. We have developed intelligent instruments for the stochastic control of laser pulse delays and a more precise control of an atomic force microscope (AFM). We have also developed demonstration experiments based on virtual instrumentation technology. Our results have been shown to the public in numerous publications: we have edited 3 books and conference proceedings, presented 6 international and 2 domestic invited talks, published 8 international and 1 domestic papers, presented 10 international and 1 domestic regular conference talks

UNCONDITIONAL SECURITY BY THE LAWS OF CLASSICAL PHYSICS

There is an ongoing debate about the fundamental security of existing quantum key exchange schemes. This debate indicates not only that there is a problem with security but also that the meanings of perfect, imperfect, conditional and unconditional (information theoretic) security in physically secure key exchange schemes are often misunderstood. It has been shown recently that the use of two pairs of resistors with enhanced Johnson-noise and a Kirchhoff-loop - i.e., a Kirchhoff-Law-Johnson-Noise (KLJN) protocol - for secure key distribution leads to information theoretic security levels superior to those of today's quantum key distribution. This issue is becoming particularly timely because of the recent full cracks of practical quantum communicators, as shown in numerous peer-reviewed publications. The KLJN system is briefly surveyed here with discussions about the essential questions such as (i) perfect and imperfect security characteristics of the key distribution, and (ii) how these two types of securities can be unconditional (or information theoretical)

Lognormal distribution of firing time and rate from a single neuron?

Even a single neuron may be able to produce significant lognormal features in its firing statistics due to noise in the charging ion current. A mathematical scheme introduced in advanced nanotechnology is relevant for the analysis of this mechanism in the simplest case, the integrate-and-fire model with white noise in the charging ion current

UNCONDITIONAL SECURITY BY THE LAWS OF CLASSICAL PHYSICS

There is an ongoing debate about the fundamental security of existing quantum key exchange schemes. This debate indicates not only that there is a problem with security but also that the meanings of perfect, imperfect, conditional and unconditional (information theoretic) security in physically secure key exchange schemes are often misunderstood. It has been shown recently that the use of two pairs of resistors with enhanced Johnson-noise and a Kirchhoff-loop - i.e., a Kirchhoff-Law-Johnson-Noise (KLJN) protocol - for secure key distribution leads to information theoretic security levels superior to those of today's quantum key distribution. This issue is becoming particularly timely because of the recent full cracks of practical quantum communicators, as shown in numerous peer-reviewed publications. The KLJN system is briefly surveyed here with discussions about the essential questions such as (i) perfect and imperfect security characteristics of the key distribution, and (ii) how these two types of securities can be unconditional (or information theoretical)