Photocurrent, Rectification, and Magnetic Field Symmetry of Induced Current Through Quantum Dots

We report mesoscopic dc current generation in an open chaotic quantum dot with ac excitation applied to one of the shape-defining gates. For excitation frequencies large compared to the inverse dwell time of electrons in the dot (i.e., GHz), we find mesoscopic fluctuations of induced current that are fully asymmetric in the applied perpendicular magnetic field, as predicted by recent theory. Conductance, measured simultaneously, is found to be symmetric in field. In the adiabatic (i.e., MHz) regime, in contrast, the induced current is always symmetric in field, suggesting its origin is mesoscopic rectification.Comment: related papers at http://marcuslab.harvard.ed

Semiclassical theory of a quantum pump

In a quantum charge pump, the periodic variation of two parameters that affect the phase of the electronic wavefunction causes the flow of a direct current. The operating mechanism of a quantum pump is based on quantum interference, the phases of interfering amplitudes being modulated by the external parameters. In a ballistic quantum dot, there is a minimum time before which quantum interference can not occur: the Ehrenfest time. Here we calculate the current pumped through a ballistic quantum dot when the Ehrenfest time is comparable to the mean dwell time. Remarkably, we find that the pumped current has a component that is not suppressed if the Ehrenfest time is much larger than the mean dwell time.Comment: 14 pages, 8 figures. Revised version, minor change

Reformation and transformation of charity work at the beginning of the new time

This article is aimed at studying the transformation of Christian charity at the beginning of the New Time and the analysis of changes ongoing in this sphere. The authors of this research start with the analysis of the situation that had been formed in the economy, culture and activity of the Roman Catholic Church in the late Middle Ages. Such a preliminary excursion into the historical domain is not coincidental. It assists understanding the reasons for the Reformation and later events. However, “in the beginning was the Word”, therefore, the text analyzes the ideas of such founding fathers of Protestantism as Martin Luther, John Calvin, Huldrych Zwingli. The new ideology along with the sociocultural and socioeconomic factors promoted the formation of a radically different and more creative social system, also including the charity sphere that became more rational, practical and rough

Photovoltaic Current Response of Mesoscopic Conductors to Quantized Cavity Modes

We extend the analysis of the effects of electromagnetic (EM) fields on mesoscopic conductors to include the effects of field quantization, motivated by recent experiments on circuit QED. We show that in general there is a photovoltaic (PV) current induced by quantized cavity modes at zero bias across the conductor. This current depends on the average photon occupation number and vanishes identically when it is equal to the average number of thermal electron-hole pairs. We analyze in detail the case of a chaotic quantum dot at temperature T_e in contact with a thermal EM field at temperature T_f, calculating the RMS size of the PV current as a function of the temperature difference, finding an effect ~pA.Comment: 4 pages, 2 figure

Temperature Dependence of Magnetophonon Resistance Oscillations in GaAs/AlAs Heterostructures at High Filling Factors

The temperature dependence of phonon-induced resistance oscillations has been investigated in two-dimensional electron system with moderate mobility at large filling factors at temperature range T = 7.4 - 25.4 K. The amplitude of phonon-induced oscillations has been found to be governed by quantum relaxation time which is determined by electron-electron interaction effects. This is in agreement with results recently obtained in ultra-high mobility two-dimensional electron system with low electron density [A. T. Hatke et al., Phys. Rev. Lett. 102, 086808 (2009)]. The shift of the main maximum of the magnetophonon resistance oscillations to higher magnetic fields with increasing temperature is observed.Comment: 5 pages, 4 figure

The status of world outlook and environmental competencies in aerospace engineering training: the general and special

The article is devoted to the study of the status of philosophical and environmental competences for engineering education programs in the field of space exploration. The authors prove that the specialists who will work in the space field in the XXI century face the most important problems, the solution of which is vital for humanity. It is stated that the quality of future decisions will be determined by the development of the philosophical and environmental ideas. It is demonstrated that these idea should necessarily have futurological character. It is suggested that the special courses aimed at the formation of futurological philosophical and environmental concepts can present as a possible solution to this problem (e.g. Creativity training for engineers, etc.)