Heat Transport from On-demand Single-Electron Sources
Doktorsavhandling, 2019
The controlled injection of quantized charge excitations from single-electron emitters into nanoscopic conductors sets the basis for many important applications ranging from metrology to the emerging field of quantum optics with electrons. Successful implementation of these applications relies not only on achieving control on the precision of the particle emission, but also on the energetic properties of the injected particles. These fundamental properties are reflected in transport observables such as time-resolved charge and energy current, as well as the spectral, i.e. energy-resolved current, or the zero-frequency correlators of charge and energy currents, thereby providing a tool for transport spectroscopy.
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.
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
thermoelectric devices
energy-selective detector
single-electron source
charge and heat currents
in Kollektorn (A423), MC2, Kemivägen 9, Chalmers, Göteborg
Opponent: Dr. Fabio Taddei, Scuola Normale Superiore and Instituto Nanoscienze-CNR, Pisa, Italy
Författare
Nastaran Dashti
Chalmers, Mikroteknologi och nanovetenskap, 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”
Nowadays, the possibility to manipulate nanodevices at the scale of single elec- trons opens a plethora of novel opportunities for electronic applications. These applications are ranging from metrology to the emerging field of quantum optics with electrons. For all of them, one needs accurate on-demand single-electron sources (SESs) that ensure well-controlled emission of electrons into the device. This thesis aims to understand the fundamental properties of single electrons emitted from such sources.
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.
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.
Styrkeområden
Nanovetenskap och nanoteknik (SO 2010-2017, EI 2018-)
Ämneskategorier
Atom- och molekylfysik och optik
Annan fysik
Den kondenserade materiens fysik
ISBN
978-91-7905-175-4
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4642
Utgivare
Chalmers
in Kollektorn (A423), MC2, Kemivägen 9, Chalmers, Göteborg
Opponent: Dr. Fabio Taddei, Scuola Normale Superiore and Instituto Nanoscienze-CNR, Pisa, Italy