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We report on a reversible structural phase transition of a two-dimensional system that can be locally induced by an external electric field. Two different structural configurations may coexist within a CO monolayer on Cu(111). The balance between the two phases can be shifted by an external electric field, causing the domain boundaries to move, increasing the area of the favored phase controllable both in location and size. If the field is further enhanced new domains nucleate. The arrangement of the CO molecules on the Cu surface is observed in real time and real space with atomic resolution while the electric field driving the phase transition is easily varied over a broad range. Together with the well-known molecular manipulation of CO adlayers, our findings open exciting prospects for combining spontaneous long-range order with man-made CO structures such as >molecule cascades> or >molecular graphene>. Our new manipulation mode permits us to bridge the gap between fundamental concepts and the fabrication of arbitrary atomic patterns in large scale, by providing unprecedented insight into the physics of structural phase transitions on the atomic scale., ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295). R.R. and N.L. acknowledge financial support from Spanish MINECO (Grant No. MAT2012-38318-C03-02 with joint financing by FEDER Funds from the European Union). P.A. acknowledges the MINCyT (project PICT Bicentenario 1962), CONICET (project PIP 0272), and UNR (project PID 19/I375) and the CCT-Rosario Computational Center. C.A.B. acknowledges financial support through the German research council (DFG).

Icosahedral virus capsids are closed shells built up with a hexagonal lattice of proteins, which incorporate pentamers at their fivefold vertices. Human adenovirus particles lose pentamers (pentons) during infection under a variety of physicochemical cues, including mechanical pulling of molecular motors and the viscous drag of the cytoplasm. By combining atomic force microscopy experiments with survival analysis and Markovian transition state theory, we investigate the sequence of adenovirus penton disassembly that reveals the aging of the virus structure. We show evidence that the lifetime of pentons gradually decreases, accompanied by capsid softening as neighboring pentons are lost. This cooperative dismantling process, which involves first-neighbor penton-penton distances of at least 45 nm, leads to a 50% increase in the virus disassembling rate of the virus particle. Theory and experiments fit remarkably well, allowing us to obtain the spontaneous escape rate and the energy barrier of penton disassembly (∼30 kBT). The observed increase in the penton's loss rate reveals long-range structural correlations within the capsid. Our estimations suggest that the mechanical cues arising from the strokes of protein motors carrying the virus to the nucleus could help penton disassembly and warrant the timely delivery of weak-enough capsids for adenovirus infection., Agencia Estatal de Investigación and European Regional Development Fund (BFU2016-74868-P and PID2019–104098 GB-I00/AEI/10.13039/501100011033); the Ministerio de Economía y Competitividad of Spain (BFU2013-41249-P and BIO2015-68990-REDT); and the Agencia Estatal CSIC (2019AEP045). The CNB-CSIC is further supported by a Severo Ochoa Excellence grant (SEV 2017-0712) and Regional Madrid Government (PEJ16/MED/TL-0935). P. J.d.P. acknowledges support by grants from the Spanish Ministry of Economy, Industry and Competitiveness projects (FIS2017- 89549-R; “Maria de Maeztu” Program for Units of Excellence in R&D MDM-2014-0377; and FIS2017-90701- REDT) Spanish Ministry of Econonomy, Industry and Competitiveness FIS2017-86007-C3-1-P

This article belongs to the Special Issue Quantum Transport in Mesoscopic Systems., his work was funded by AEI grant numbers MAT2017-82639 and MDM2017-0711.

Electrons have played a significant role in the development of many fields of physics during the last century. The interest surrounding them mostly involved their wave-like features prescribed by the quantum theory. In particular, these features correctly predict the behaviour of electrons in various physical systems including atoms, molecules, solid-state materials, and even in free space. Ten years ago, new breakthroughs were made, arising from the new ability to bestow orbital angular momentum (OAM) to the wave function of electrons. This quantity, in conjunction with the electron's charge, results in an additional magnetic property. Owing to these features, OAM-carrying, or twisted, electrons can effectively interact with magnetic fields in unprecedented ways and have motivated materials scientists to find new methods for generating twisted electrons and measuring their OAM content. Here, we provide an overview of such techniques along with an introduction to the exciting dynamics of twisted electrons.

In a tutorial article directed to serve researchers, university teachers and students, we study Boltzmann kinetic equation (BKE), which in its application to nanoelectronics serves to solve the same problems as the generalized Landauer-Datta-Lundstrom (LDL) transport model does. For some problems BKE formalism is preferable, for the other – LDL model is. Under correct performance of calculations the two approaches leads to similar results. In this article we answer the following questions: how to compose the equation for distribution function f (r, k, t) as a solution of BKE beyond equilibrium, how to solve this equation for the linear response regime, how to compare the obtained results with those, which can be obtained within LDL model for diffusive transport regime, how to take into consideration the external magnetic field and its effect on electron transport.We formulate BKE in the approximation of relaxation time (RT) and search for its solution in the dynamic equilibrium regime. Than we calculate the transport coefficients. We consider the calculation of the surface concentration of electrons in 2D resistor as an example. The solution for BKE in quasi-equilibrium regime within RT approximation is the expression, well known for LDL model. We also demonstrate that BKE within RT approximation leads to the same expressions for Seebeck coefficient and electron thermo-conductivity, as LDL transport model does. The LDL model advantage is its physical transparency and the fact that it enables to consider quasi-ballistic and ballistic transport regimes as simply, as the diffusive one. On the other hand, BKE formalism should be used for studies of the anisotropic transport., В методической статье, рассчитанной на исследователей, преподавателей и студентов высшей школы, мы рассматриваем кинетическое уравнение Больцмана (КУБ), которое в применении к наноэлектронике решает те же самые задачи, что и обобщенная транспортная модель Ландауэра – Датты – Лундстрома (ЛДЛ). Для одних задач лучше пользоваться КУБ, а для других – моделью ЛДЛ. При правильной постановке вычислений оба подхода приводят к одним и тем же результатам. В нашей статье рассматриваются следующие вопросы: как составить уравнение для функции распределения f (r, k, t) как решения КУБ за пределами равновесия, как решить это уравнение в режиме линейного отклика, как увязать полученные таким образом результаты с теми, которые получаются в модели ЛДЛ в диффузионном режиме транспорта, как учесть внешнее магнитное поле и его влияние на электронный транспорт., У методичній статті, розрахованій на науковців, викладачів та студентів вищої школи, розглядається кінетичне рівняння Больцмана (КРБ), яке в застосуванні до наноелектроніки розв’язує ті ж завдання, що й узагальнена транспортна модель Ландауера – Датта – Лундстрома (ЛДЛ). Для одних задач краще використовувати КРБ, а для других – модель ЛДЛ. За правильного виконання обчислювальних процедур обидва підходи дають однин і той самий результат. У цій статті дано відповідь на такі питання: як скласти рівняння для функції розподілу f (r, k, t) як розв’язку КРБ за межами рівноваги, як розв’язати це рівняння в режимі лінійного відгуку, як зіставити отримані таким чином результати з тими, які можна отримати в моделі ЛДЛ в дифузійному режимі транспорту, як врахувати зовнішнє магнітне поле і його вплив на електронний транспорт.Ми формулюємо КРБ в наближенні часу релаксації (ЧР) й шукаємо його розв’язок у режимі динамічної рівноваги. Потім розраховуємо транспортні коефіцієнти. Як приклад розглядаємо обчислення поверхневої концентрації електронів у 2D провіднику. Результатом розв’язування КРБ в квазірівноважному режимі в наближенні ЧР, або, що те саме, в дифузійному наближенні, для поверхневої провідності стає звичайний для моделі ЛДЛ вираз. Показано також, що КРБ у наближенні ЧР дає ті ж самі вирази для коефіцієнта Зеєбека й для електронної теплопровідності, що й транспортна модель ЛДЛ. Перевага моделі ЛДЛ в її фізичній прозорості, а також у тому, що вона дозволяє розглядати квазібалістичний і балістичний режими транспорту так само просто, як і дифузійний режим. З другого боку, без КРБ не можна обійтися при вивченні анізотропного транспорту.

When atoms come together and bond, these new states are called molecules and their properties determine many aspects of our daily life. Strangely enough, it is conceivable for light and molecules to bond, creating new hybrid light–matter states with far-reaching consequences for these strongly coupled materials. Even stranger, there is no “real” light needed to obtain the effects; it simply appears from the vacuum, creating “something from nothing.” Surprisingly, the setup required to create these materials has become moderately straightforward. In its simplest form, one only needs to put a strongly absorbing material at the appropriate place between two mirrors, and quantum magic can appear. Only recently has it been discovered that strong coupling can affect a host of significant effects at a material and molecular level, which were thought to be independent of the “light” environment: phase transitions, conductivity, chemical reactions, etc. This review addresses the fundamentals of this opportunity: the quantum mechanical foundations, the relevant plasmonic and photonic structures, and a description of the various applications, connecting material chemistry with quantum information, entanglement, nonlinear optics, and chemical reactivity. Ultimately, revealing the interplay between light and matter in this new regime opens attractive avenues for various new technologies.

The analog of two seminal quantum optics experiments are considered in a condensed matter setting with single electron sources injecting electronic wave packets on edge states coupled through a quantum point contact. When only one electron is injected, the measurement of noise correlations at the output of the quantum point contact corresponds to the Hanbury-Brown and Twiss setup. When two electrons are injected on opposite edges, the equivalent of the Hong-Ou-Mandel collision is achieved, exhibiting a dip as in the coincidence measurements of quantum optics. The Landauer-Buttiker scattering theory is used to first review these phenomena in the integer quantum Hall effect, next, to focus on two more exotic systems: edge states of two dimensional topological insulators, where new physics emerges from time reversal symmetry and three electron collisions can be achieved; and edges states of a hybrid Hall/superconducting device, which allow to perform electron quantum optics experiments with Bogoliubov quasiparticles., Comment: 13 pages, 10 figures, invited contribution for a focus issue on "Single-electron control in solid-state devices"

We present superconducting microwave-frequency resonators based on NbTiN nanowires. The small cross section of the nanowires minimizes vortex generation, making the resonators resilient to magnetic fields. Measured intrinsic quality factors exceed $2\times 10^5$ in a $6$ T in-plane magnetic field, and $3\times 10^4$ in a $350$ mT perpendicular magnetic field. Due to their high characteristic impedance, these resonators are expected to develop zero-point voltage fluctuations one order of magnitude larger than in standard coplanar waveguide resonators. These properties make the nanowire resonators well suited for circuit QED experiments needing strong coupling to quantum systems with small electric dipole moments and requiring a magnetic field, such as electrons in single and double quantum dots.

We study geometrical confinement effects in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8 +\delta}$ mesoscopic vortex-matter with edge-to-surface ratio of $7-12$%. Samples have in-plane square and circular edges, 30\,$\mu$m widths, and $\sim 2\,\mu$m thickness. Direct vortex imaging reveals the compact planes of the structure align with the sample edge by introducing topological defects. The defects density is larger for circular than for square edges. Molecular dynamics simulations suggest this density is not an out-of-equilibrium property but rather determined by the geometrical confinement., Comment: accepted in Journal of Low Temperature Physics

International audience; We study the interaction between a solid particle and a liquid interface. A semianalytical solution of the nonlinear equation that describes the interface deformation points out the existence of a bifurcation behavior for the apex deformation as a function of the distance. We show that the apex curvature obeys a simple power-law dependency on the deformation. Relationships between physical parameters disclose the threshold distance at which the particle can approach the liquid before capillarity provokes a "jump to contact". A prediction of the interface original position before deformation takes place, as well as the attraction force measured by an approaching probe, are produced. The results of our analysis agree with the force curves obtained from atomic force microscopy experiments over a liquid puddle.

Resonantly enhanced emission from the zero-phonon line of a diamond nitrogen-vacancy (NV) center in single crystal diamond is demonstrated experimentally using a hybrid whispering gallery mode nanocavity. A 900 nm diameter ring nanocavity formed from gallium phosphide, whose sidewalls extend into a diamond substrate, is tuned onto resonance at a low temperature with the zero-phonon line of a negatively charged NV center implanted near the diamond surface. When the nanocavity is on resonance, the zero-phonon line intensity is enhanced by approximately an order of magnitude, and the spontaneous emission lifetime of the NV is reduced by as much as 18%, corresponding to a 6.3X enhancement of emission in the zero photon line.

Предложен численный метод измерения формы локального атомного образования, обладающего хорошо определенной внешней границей. Проведен анализ алгоритмов, разработано необходимое программное обеспечение и на примере модельных кластеров проведено его тестирование. Выполнено измерение формы последовательности равновесных кластеров, взаимодействие частиц в которых описывается потенциалом Леннарда-Джонса. Показано, что в предложенном методе для таких кластеров корректно воспроизводятся осцилляции размерных эффектов и последовательность магических чисел. // Eng Numerical technique for measurement the form of local atomic formation with well-defined exterior boundary was presented. Algorithms were analyzed, necessary software was developed and tested for the model clusters. For the series of equilibrium clusters with Lennard-Jones interparticle interactions the form of clusters was measured. It was shown that for such clusters within the framework of proposed method both the oscillations of size-dependent properties and sequence of magic numbers are correctly reproduced. При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/2647

International audience; The purpose of the present paper is to propose two scenarios for measuring high frequency noise. The first one uses inductive coupling to an LC circuit, and describes the measurement of noise cross-correlations as in an Hanbury-Brown and Twiss geometry. The second one uses the photo-assisted transfer of two electrons in a normal metal--superconductor circuit, which is capacitively coupled to the mesoscopic circuit to be measured.

Within the «bottom – up» approach of nanoelectronics the equilibrium thermodynamics of a conductor with a current is presented and the accumulation of information in a non-equilibrium state with an analysis of information-driven battery model is discussed in connection with the Landauer principle on the minimum of energy needed to erase one bit of information. The concept of quantum entropy is introduced and the importance of integration of spintronics and magnetronics in connection with the upcoming development of the spin architecture for the computing devices are discussed

Scattering of carriers in the LDL transport model during the changes of the scattering times in the collision processes is considered qualitatively. The basic relationship between the transmission coefficient T and the average mean free path is derived for 1D conductor. As an example, the experimental data for Si MOSFET are analyzed with the use of various models of reliability.

The role of the Boltzmann transport equation (BTE) in the Landauer-Datta - Lundstrom (LDL) electron and heat transport model is discussed. As the applications of the BTE there are discussed the BTE in the relaxation time approximation and the behavior of electric current in an external magnetic field as well as expression for the surface conductivity well knownintheLDLmodelisdeduced

The appearance of “magic” heights of Pb islands grown on Cu(111) is studied by self-consistent electronic structure calculations. The Cu(111) substrate is modeled with a one-dimensional pseudopotential reproducing the essential features, i.e., the band gap and the work function, of the Cu band structure in the [111] direction. Pb islands are presented as stabilized jellium overlayers. The experimental eigenenergies of the quantum-well states confined in the Pb overlayer are well reproduced. The total energy oscillates as a continuous function of the overlayer thickness reflecting the electronic shell structure. The energies for completed Pb monolayers show a modulated oscillatory pattern reminiscent of the supershell structure of clusters and nanowires. The energy minima correlate remarkably well with the measured most probable heights of Pb islands. The proper modeling of the substrate is crucial to set the quantitative agreement., This work was partially supported by the University of the Basque Country (Grant No. UPV00224.310-14553/2002), Departamento de Educacion del Gobierno Vasco (Grant No. MAT 2001-0946), Spanish MCyT (Grants Nos. PB98-0870-C02 and MAT 2002-04087-C02-01), and by the Academy of Finland through its Centre of Excellence Program (2000-2005).

Обсуждаются такие свойства графена как плотность электронных состояний и носителей тока, число мод и максимальная проводимость, рассеяние и подвижность в графене, циклотронная частота и эффективная масса, плотность фононных состояний, сравнительный вклад электронов и фононов в теплопроводность графена. В справочных целях дается сводка термоэлектрических коэффициентов для графена в баллистическом и диффузионном режимах проводимости со степенным законом рассеяния

С позиций концепции «снизу – вверх» транспортной модели Ландауэра-Датты-Лундстрома современной наноэлектроники рассматриваются термоэлектрические явления Зеебека и Пельтье и качественно обсуждаются закон Видемана-Франца, числа Лоренца и основные уравнения термоэлектричества с четырьмя транспортными коэффициентами – удельное сопротивление, коэффициенты Зеебека и Пельтье и электронная теплопроводность.

On the basis of the «bottom – up» approach of Landauer-Datta-Lundstrom transport model the basic equations of thermoelectricity with the corresponding transport coefficients for 1D conductors in the ballistic regime and 3D conductors in the diffusion regime with an arbitrary dispersion and for any size were strictly derived. The thermoelectric coefficients for 1D, 2D, and 3D semiconductors with parabolic dispersion in the ballistic and diffusive regimes are expressed through standard Fermi-Dirac integrals.

Излагается обобщенная модель транспорта электронов, развитая Р. Ландауэром, С. Даттой и М. Лундстромом, вплоть до вычисления проводимости резисторов любой размерности, любого масштаба и произвольной дисперсии, работающих в баллистическом, квази-баллистическом или диффузионном режиме линейного отклика как вблизи 0º K, так и при высоких температурах. Обсуждаются и поныне широко используемое понятие подвижности, а также диссипация тепла и падение напряжения в баллистических резисторах.

International audience; Phase transitions in superconducting mesoscopic disks have been studied over the $H-T$ phase diagram through heat capacity measurement of an array of independent aluminium disks. These disks exhibit non periodic modulations versus $H$ of the height of the heat capacity jump at the superconducting to normal transition. This behaviour is attributed to giant vortex states characterized by their vorticity $L$. A crossover from a bulk-like to a mesoscopic behaviour is demonstrated. $C_{\rm p}$ versus $H$ plots exhibit cascades of phase transitions as $L$ increases or decreases by one unity, with a strong hysteresis. Phase diagrams of giant vortex states inside the superconducting region are drawn in the vortex penetration and expulsion regimes and phase transitions driven by temperature between vortex states are thus predicted in the zero field cooled regime before being experimentally evidenced.