Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "Stefanski, P." wg kryterium: Autor


Tytuł:
Probing Fractional Josephson Junction with a Quantum Dot
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/1398600.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.-b
73.21.La
74.78.Na
74.50.+r
Opis:
We consider theoretically a junction between two topological superconducting wires, mediated by a quantum dot. The wires are modelled by the Kitaev chains tuned into topological phase, which possess unpaired Majorana states at their ends. We derive the low energy Hamiltonian of the model. The Majorana states closer to the dot convert into the Dirac fermion inside the dot, forming fractional Josephson junction. The dot is additionally weakly coupled to the normal tunneling probe allowing transport measurement through the dot. When the topological wires are short, the unpaired Majorana end-states can hybridize inside the wire forming an extended Dirac fermionic state. It yields the destruction of the extended state in the dot. We discuss the dependence of the spectral density of the dot and its conductance on superconducting phase. We show that the conservation of parity of the junction, crucial for successful measurement of the fractional effect, can be assured by the gate voltage manipulation of the dot level position and that in case of an unpaired Majorana state in the junction a half conductance quantum can be observed.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 554-557
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coqblin-Schrieffer Impurity with Local Exchange Coupling: a Perturbative Approach
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/2013008.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Hf
71.20.Eh
72.15.Qm
75.20.Hr
Opis:
The Coqblin-Schrieffer one-impurity model with the additional local exchange interaction is studied within diagrammatic approach. The Ruderman-Kittel-Kasuya-Yoshida-type local exchange interaction between f electrons of the impurity and a channel of conduction electron l=0 partial waves is treated in the molecular field approximation. The perturbation expansion resummation for the Coqblin-Schrieffer hybridization mediated interaction vertex part is carried out in the ladder approximation yielding the formula for the Kondo temperature T$\text{}_{K}$ decreasing with increased local exchange. Moreover, the temperature divergence of the susceptibility at T$\text{}_{K}$ is shifted towards T=0. For some critical strength of the local exchange interaction the susceptibility approaches a Curie-type dependence as for an uncompensated impurity magnetic moment. A relation to the "Kondo disorder" model, which leads to the non-Fermi-liquid behavior, is discussed.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 385-388
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Single-Ion Rare Earth Anisotropy in ThMn$\text{}_{12}$-Type Compounds
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/1931244.pdf
Data publikacji:
1994-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Gg
Opis:
The single-ion rare earth anisotropy was investigated in ThMn$\text{}_{12}$-type compounds. For this purpose the crystal electric field parameter values were studied. In these compounds, described by formula RFe$\text{}_{12-x}$T$\text{}_{x}$, R = rare earth, T = Ti, V, Cr, Mo, W and Si, the T atoms have strong crystallographic site preference changing the local crystal electric field potential which "sees" the rare earth ion. The crystal electric field potentials A$\text{}_{2}^{0}$ were calculated considering this site preference. The summations were performed taking into account the nearest neighborhood of the rare earth ion according to the recent results of band structure calculations. The charges of the surrounding Fe and T atoms were established applying the chemical bond model proposed by Pauling. The absolute value of A$\text{}_{2}^{0}$ decreases when the content of vanadium increases in 8(i) position, which is in agreement with experimental data. Localization of Si atoms in 8(j) and 8(f) causes a decrease in A$\text{}_{2}^{0}$. The $\text{}^{155}$Gd Mössbauer spectroscopy data confirm this fact. Miedema's "macroscopic" atom model of cohesion in alloys was applied for interpretation of the role of T atoms in the isomer shift and volume effects.
Źródło:
Acta Physica Polonica A; 1994, 85, 3; 615-621
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Majorana States in Presence of Electron Interactions: Spinful Fractional Josephson Junction with a Quantum Dot
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/1029763.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.-b
73.21.La
31.15.V-
74.50.+r
Opis:
We consider a fractional Josephson junction mediated by a quantum dot in which the Zeeman field arising from the magnetic fields driving left and right wires into topological phase can be tuned. Both fields, forming an angle Θp, can be rotated in the common plane perpendicular to the spin-orbit field in the wires. For Θp=0 the dot can be regarded as effectively non-interacting due to the large Zeeman splitting, whereas for Θp ≤sssimπ electron interactions are switched on the dot, affecting Majorana states. The tunnel electrode, weakly coupled to the dot from the top, allows to probe their density of states via conductance measurement. We show that electron interactions renormalize Majorana peak and introduce characteristic asymmetry in the gate voltage dependence of the transverse zero-bias conductance through the dot.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 362-365
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Dependent Fano Resonances in a Rashba System with Coulomb Interactions
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/2048075.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
72.25.Dc
73.40.Sx
Opis:
The effects of interplay of interference of quantum mechanical electron waves and their mutual Coulomb interactions are investigated in the device composed of interacting quantum dot attached to polarized leads via quantum point contacts with the Rashba interaction. The Zeeman-split dot sub-levels form two interfering channels and as a result spin dependent Fano resonances arise in the conductance through the system. The Coulomb repulsion between the channels modifies the width and shape of the Fano resonances as compared to the non-interacting case. We formulate the Fano expression dependent on the dot's occupancy regulated by the Coulomb interactions.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 644-647
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Level Occupancy Anomalies in a Double QD System
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/1810305.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.Kv
73.23.Hk
Opis:
A double quantum dot system is considered in the presence of the electron intra-Coulomb U interactions within the dots and inter-Coulomb $U_{12}$ interactions between them. We show that both for spinless and spinfull electrons the dots occupancy anomalies are encountered and caused by electron correlations. This non-monotonic behavior strongly deviates from usual level filling at the Coulomb blockade. For spinfull electrons the inter-dot interaction modifies also on-site electron correlations.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 92-94
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Signatures of Majorana States in Electron Transport through a Quantum Dot Coupled to a Topological Wire
Autorzy:
Stefański, P.
Powiązania:
https://bibliotekanauki.pl/articles/1384812.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.-b
73.23.Hk
73.21.La
74.78.Na
Opis:
We consider theoretically a system composed of a quantum dot coupled to a topological superconducting wire. The dot, being in Coulomb blockade (CB) regime is additionally coupled to the normal leads. The topological wire hosts Majorana states, which, as we show, characteristically modifies conductance through the dot. An unpaired Majorana state in the wire causes a unique temperature dependence of zero bias conductance vs. gate voltage. It decreases in-between CB peaks and on the sides of the peaks from the plateau at ~ e²/2h when temperature increases. At the same time conductance increases at the CB peak positions. It is accompanied by zero bias anomaly in differential conductance. For finite overlap of Majorana states in the wire the zero bias anomaly disappears. Instead, two characteristic Fano resonances of opposite symmetry appear, positioned mirror-symmetrically with respect to zero bias.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 198-200
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interplay of Kondo and Fano Resonance in Electronic Transport in Nanostructures
Autorzy:
Bułka, B. R.
Stefański, P.
Tagliacozzo, A.
Powiązania:
https://bibliotekanauki.pl/articles/2043700.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.-b
72.15.Qm
75.20.Hr
Opis:
Quantum interference and electronic correlations are processes relevant for electronic transport in nanostructures. We present theoretical studies of transport for various models, which take into account these processes and describe the Fano resonance as well as many-body effects like the Kondo resonance. The results are compared with transport measurements performed on a small quantum dot strongly coupled to electrodes, a large semi-open quantum dot, a side-attached quantum dot to a quantum wire systems and a quantum dot embedded in the metallic ring. We show how conductance characteristics of the Kondo and the Fano resonance are modified in different situations.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 555-569
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground State Properties of Tb$\text{}^{3+}$ Ion in TbNi$\text{}_{10}$Si$\text{}_{2}$
Autorzy:
Stefański, P.
Suski, W.
Wochowski, K.
Mydlarz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1964565.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Gg
Opis:
Ground state properties of Tb$\text{}^{3+}$ ion were investigated in the tetragonal ThΜn$\text{}_{12}$-type TbNi$\text{}_{10}$Si$\text{}_{2}$ compound on the basis of temperature dependence of the paramagnetic susceptibility and magnetization measurements. The rare earth temperature dependence of the susceptibility was calculated using the Van Vleck equation. The Γ$\text{}_{t5}^{(1)}$ doublet is suggested to be a ground state separated by 9 K from the first excited singlet Γ$\text{}_{t1}^{(2)}$. The magnetic moment associated with the ground state doublet agrees with saturation magnetization data at 4.2 K. The overall crystal field splitting is estimated to be 105 K.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 281-284
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie pracy przy podkrzesywaniu drzew - czasochlonnosc i wydajnosc
Autorzy:
Giefing, D.F.
Holota, R.
Stefanski, P.
Srednicki, J.
Powiązania:
https://bibliotekanauki.pl/articles/812975.pdf
Data publikacji:
1996
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
czasochlonnosc
podkrzesywanie drzew
wydajnosc pracy
lesnictwo
zabiegi pielegnacyjne
Źródło:
Sylwan; 1996, 140, 01; 37-44
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Reorientation and Exchange Coupling in the Dy$\text{}_{1-x}$Er$\text{}_{x}$Fe$\text{}_{10}$Si$\text{}_{2}$ Compounds
Autorzy:
Stefański, P.
Kowalczyk, A.
Skoryna, D.
Szlaferek, A.
Wrzeciono, A.
Powiązania:
https://bibliotekanauki.pl/articles/1929845.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Gg
Opis:
The structural and magnetic properties of Dy$\text{}_{1-x}$Er$\text{}_{x}$Fe$\text{}_{10}$Si$\text{}_{2}$ are investigated. X-ray analysis reveals that these compounds are of the tetragonal ThMn$\text{}_{12}$ structure. In this structure the rare earth atoms occupy one crystallographic position 2(a). The unit cell contains 26 atoms. The spin reorientation temperature, T$\text{}_{SR}$, was measured from the temperature dependence of the initial susceptibility using an ac bridge of mutual inductance of the Harsthorn type. Dy$\text{}^{+3}$ and Er$\text{}^{+3}$ have opposite contributions to the entire magnetic anisotropy. The spin reorientation temperature is found to be about 271 K in DyFe$\text{}_{10}$Si$\text{}_{2}$ and 48 K in ErFe$\text{}_{10}$Si$\text{}_{2}$. The values are discussed applying the crystal field model. The value of the rare earth-transition metal exchange coupling constant J$\text{}_{RFe}$/k$\text{}_{B}$ derived from the mean-field model analysis of the Curie temperature is about -13 K. The Fe-Fe exchange integral is much higher and is equal to about 75 K.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 259-262
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability analysis of interconnected discrete-time fractional-order LTI state-space systems
Autorzy:
Grzymkowski, Łukasz
Trofimowicz, Damian
Stefański, Tomasz P.
Powiązania:
https://bibliotekanauki.pl/articles/1838161.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
stability analysis
discrete time system
fractional order system
analiza stabilności
układ czasu dyskretnego
układ rzędu ułamkowego
Opis:
In this paper, a stability analysis of interconnected discrete-time fractional-order (FO) linear time-invariant (LTI) state-space systems is presented. A new system is formed by interconnecting given FO systems using cascade, feedback, parallel interconnections. The stability requirement for such a system is that all zeros of a non-polynomial characteristic equation must be within the unit circle on the complex z-plane. The obtained theoretical results lead to a numerical test for stability evaluation of interconnected FO systems. It is based on modern root-finding techniques on the complex plane employing triangulation of the unit circle and Cauchy’s argument principle. The developed numerical test is simple, intuitive and can be applied to a variety of systems. Furthermore, because it evaluates the function related to the characteristic equation on the complex plane, it does not require computation of state-matrix eigenvalues. The obtained numerical results confirm the efficiency of the developed test for the stability analysis of interconnected discrete-time FO LTI state-space systems.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2020, 30, 4; 649-658
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relationship between pH of ruminal fluid during subacute ruminal acidosis and physiological response of the Polish Holstein-Friesian dairy cows
Autorzy:
Stefańska, B.
Pruszyńska-Oszmałek, E.
Szczepankiewicz, D.
Stajek, K.
Stefański, P.
Gehrke, M.
Nowak, W.
Powiązania:
https://bibliotekanauki.pl/articles/2087914.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Źródło:
Polish Journal of Veterinary Sciences; 2017, 3; 551-558
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Subjective and Objective Comparative Study of DAB+ Broadcast System
Autorzy:
Gilski, P.
Stefański, J.
Powiązania:
https://bibliotekanauki.pl/articles/177540.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
audio quality assessment
broadcasting
digital audio broadcasting
quality of experience
quality of service
radio communication
Opis:
Broadcasting services seek to optimize their use of bandwidth in order to maximize user’s quality of experience. They aim to transmit high-quality digital speech and music signals at the lowest bitrate. They intend to offer the best quality under available conditions. Due to bandwidth limitations, audio quality is in conflict with the number of transmitted radio programs. This paper analyzes whether the quality of real-time digital DAB+ broadcasted radio programs surpasses the quality offered by analog FM radio. We also perform a subjective and objective quality assessment comparative study of the HE-AAC v2 audio codec used in DAB+. The subjective studies were carried out using the MOS test methodology, whereas the objective tests were realized using the ViSQOLAudio metric. These studies were followed by a questionnaire concerning the migration from analog to digital radio domain.
Źródło:
Archives of Acoustics; 2017, 42, 1; 3-11
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quality Expectations of Mobile Subscribers
Autorzy:
Gilski, P.
Stefański, J.
Powiązania:
https://bibliotekanauki.pl/articles/307922.pdf
Data publikacji:
2015
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
cellular networks
mobile communication
quality of experience
quality of service
wireless communication
Opis:
Mobile systems, by nature, have finite resources. Radio spectrum is limited, expensive and shared between many users and services. Mobile broadband networks must support multiple applications of voice, video and data on a single IP-based infrastructure. These converged services each have unique traffic holding and quality requirements. A positive user experience must be obtained through efficient partitioning of the available wireless network resources. The 3rd Generation Partnership Project (3GPP) has developed a comprehensive Quality of Service (QoS) parameter to address this problem. The regular control of service quality is critical for operators to ensure user Quality of Experience (QoE), establish new business models and monetize services. It enables operators to employ fair-use resource policies and maintain network performance during peak traffic times. Wireless mobile communication is tending towards an integrated system of Internet and telecommunication technologies, where mobile users move freely anytime and everywhere. They desire to communicate with any device using the best service available. In this paper QoS management issues in mobile communication are described. The authors present an insight into subscriber behavior and related factors that affect the QoE of mobile data services.
Źródło:
Journal of Telecommunications and Information Technology; 2015, 1; 15-19
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies