Über Privates und Öffentliches

ÜBER PRIVATES UND ÖFFENTLICHES Über Privates und Öffentliches / Schröter, Ursula (Rights reserved) ( -

Destructive interference in transfer rates by coherent coupling to a remote reservoir

Transport through two point-contacts in series, even with arbitrarily high transmissions, can be modeled with rate equations if the rates are deduced from the quantum mechanical current formula, which thus accounts for interferences on the wavefunction level. An expression using Green s functions giving the current through a single contact is valid for evaluating the charging rates of the enclosed island in the double-junction system, even in the case of coherent coupling all over the island from lead to lead. We demonstrate that these current rates for each junction can be rewritten as 2-products of the so-called transfer Green functions, maintaining formal analogy to the single-junction case. On the one hand this facilitates numerical calculations. On the other hand, the form of the rate terms reveals how besides direct coupling across one junction effective coupling between the involved and the remote lead contributes to transfers across the regarded junction and how coherent loss from the island across the other junction diminishes the rate. It is further explained that for the double junction in the case of coherent coupling between both contacts direct lead-to-lead transport adds current contributions; however, interferences are expected to reduce the net current as compared to incoherent mutual influence via the island charging only. Crossed Andreev reflection in the superconducting state within the premises of our model cannot surpass other transport processes such as to cause extra steps in current voltage curves or negative differential conductance

Modelling partially coherent transport across an island - multiple Andreev reflection and charging effects

A Green's functions technique known to describe transport through a superconducting point contact with multiple Andreev reflection is merged with a rate equation scheme and thus extended to model transport through a series of two junctions enclosing an island between them. In the superconducting state such systems may show an interplay of multiple Andreev reflection and Coulomb blockade. Although not of unique shape calculated current-voltage characteristics exhibit more or less pronounced steps that can be associated to transport processes setting in because of the applied voltage becoming sufficient to overcome certain fractions of the superconductor gap or providing the required charging energy. The speciality of our model, however, lies in regarding all single-charge transfers out of every-order multiple reflection simultaneously instead of adding total rates for processes up to some order. The algorithm can treat series of junctions that are just incoherently coupled via the electrostatic charge on the island as well as transport maintaining coherence across the island. In the latter case we find direct lead-to-lead transport, but interestingly, Coulomb blockade never completely vanishes in our model. In principle, the scheme is also applicable to a mixed situation where interaction between the junctions is partly coherent and partly incoherent

Charging effects and Andreev reflection in a double-junction circuit : a model approach combining rate equations and Green s functions

We present a qualitative model for current transport in the superconducting state through a series of two quantum-point contacts with a mesoscopic island between them. A Green s functions technique is merged with a rate-equation method in order to account for phase as well as charging effects. Multiple Andreev reflections are included in a nonperturbative manner and therefore our Ansatz despite some underlying assumptions is in principle not restricted to the low or high transmission regime. We find that in our system, multiple Andreev reflection is not totally suppressed by Coulomb blockade, but that the step pattern of current-voltage characteristics is determined by an interplay of multiple thresholds

Transfer Green s functions in two-fold interaction systems

For systems governed by two kinds of interactions it is shown that these can be built successively into the Green s functions describing the system s response. Whereas for the ordinary Green s function the Dyson equation to solve has the same form in each step, we derive the non-trivial second-step equation for the transfer or coupling function, which on the one hand is closely related to the self-energy and on the other hand of practical relevance in transport calculations

Coulomb blockade versus coherence in transport through a double junction

We construct a model describing current transport through a superconducting or normal conducting circuit consisting of two point contacts in series by extending a Green s functions technique. In between the contacts is a mesoscopically large and bulklike island. The model can, in principle, handle contacts in all transmission regimes. Coherent interaction throughout the whole system is included in the form of multiple and multiple Andreev reflections extending over both contacts while accounting for charging effects by a changing electrostatic potential of the island. Our calculations show that even though the onsets of certain current contributions are independent of the island charging energy, Coulomb blockade persists, especially in the normal state. Coulomb staircases can still be visible but get smeared out for particular ratios of the charging energy and the gap in the superconducting state. However, as a general trend, we find that including coherent coupling across the island does not very significantly change the shape of the current-voltage curves compared to the incoherent results

Sterbegebetlein Simeonis. Aus dem 2. Capitel S. Lucae : Erklähret und ausgeleget Bey ... Leichbegengniß der ... Ursulen/ Des ... Friederich Schröters ... Bürgers und Handelsman zu Weimar ... Haußehren/ Welche den 9. Octobris, Anno 1615. ... entschlaffen/ und folgends den 12. eiusd. Christlich zur Erden bestattet / Durch M. Eliam Schönfelden/ Diaconum daselbst

STERBEGEBETLEIN SIMEONIS. AUS DEM 2. CAPITEL S. LUCAE : ERKLÄHRET UND AUSGELEGET BEY ... LEICHBEGENGNISS DER ... URSULEN/ DES ... FRIEDERICH SCHRÖTERS ... BÜRGERS UND HANDELSMAN ZU WEIMAR ... HAUSSEHREN/ WELCHE DEN 9. OCTOBRIS, ANNO 1615. ... ENTSCHLAFFEN/ UND FOLGENDS DEN 12. EIUSD. CHRISTLICH ZUR ERDEN BESTATTET / DURCH M. ELIAM SCHÖNFELDEN/ DIACONUM DASELBST Sterbegebetlein Simeonis. Aus dem 2. Capitel S. Lucae : Erklähret und ausgeleget Bey ... Leichbegengniß der ... Ursulen/ Des ... Friederich Schröters ... Bürgers und Handelsman zu Weimar ... Haußehren/ Welche den 9. Octobris, Anno 1615. ... entschlaffen/ und folgends den 12. eiusd. Christlich zur Erden bestattet / Durch M. Eliam Schönfelden/ Diaconum daselbst (1) Einband (1) Titelblatt (3) Auslegung (5) Der erste Theil (8) Der ander Theil (16) Der dritte Theil (24) Fotodokumentation (35