Heat Transport from On-demand Single-Electron Sources
This thesis deals with two important aspects of the characterization of different time-dependently driven single-electron sources (SES): it provides (i) a detailed analysis of the aforementioned observables and (ii) proposals for the readout of such transport properties. First, we analyze in detail the transport observables in three different SESs. The SESs differ by the characteristics of the applied time-dependent driving voltage and by the degree of particle confinement in the driven conductor; their common feature is that pulses of quantized charge are produced going along with a minimal excitation of the Fermi sea. We point out the impact of the device design and of tunable external pa- rameters, such as temperature, on the transport observables. Second, we the- oretically propose ways to experimentally access the transport observables. Charge transport observables are standardly detected for different kinds of sources. In contrast, energy transport–particularly energy-current noise– is more difficult to access experimentally. We propose a setup for the detection of fluctuating charge and energy currents, as well as their correlations, generated by a SES, via reading out frequency-dependent electrochemical- potential and temperature fluctuations in a probe contact. Furthermore, in a second proposal, we investigate how to access the spectral current, giving access to the particles’ energy distribution, in an energy-selective detector setup. More specifically, we propose to readout modifications of thermoelectric response coefficients due to the time-dependent driving as a measure of the spectral current. However, importantly, this type of setup also opens completely novel routes: we find that SESs can be used as probes to sense until now unexplored quantum screening effects in thermoelectric transport.
fluctuations and noise
charge and heat currents
Chalmers, Mikroteknologi och nanovetenskap (MC2), Tillämpad kvantfysik
N. Dashti, S. Kheradsoud, M. Misiorny, P. Samuelsson, and J. Splettstoesser, “ Screening effects in the interplay between thermoelectric response and time-dependent driving”
Usually, when one talks about current sources in the context of electronic circuits, one typically thinks of currents carrying an almost continuous stream on the order of 10^16 electrons per second. In contrast, the SESs discussed in this thesis are capable of emitting well-separated charge pulses, each carrying no more than a few or even a single electron. As a result, one gains precise control over the emitted pulse which, in turn, is crucial for the aforementioned electronic applications. Such prospective applications serve as our key motivation for investigating different characterization tools for the properties of SESs. These properties are, in particular, fluctuations in the emission and the energy spectrum of the emitted electrons. They can be revealed by measurements of charge and heat carried by these currents. In this thesis we study charge and heat currents from SESs and propose devices and schemes for their readout.
Nanovetenskap och nanoteknik (2010-2017)
Atom- och molekylfysik och optik
Den kondenserade materiens fysik
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4642
Chalmers tekniska högskola
in Kollektorn (A423), MC2, Kemivägen 9, Chalmers, Göteborg
Opponent: Dr. Fabio Taddei, Scuola Normale Superiore and Instituto Nanoscienze-CNR, Pisa, Italy