Dynamics and thermodynamics of nanoscale devices
Applied Quantum Physics
MC2 - Department of Microtechnology and Nanoscience
Chalmers University of Technology
S-412 96 Göteborg
Sweden
News....
2nd of April 2024
Welcome Bruno!! Bruno Bertin started as a new postdoc in the group. He will work on thermodynamic aspects of time-dependent quantum transport.
29th of August
Congratulations to Sushanth Varada for a very successful master thesis defense today at Chalmers, with the title "Anyon Colliders: A time-dependent quantum Hall particle collider to reveal fractional statistics in the Laughlin sequence"
23rd of August 2023
Congratulations to Ludovico, who won the poster prize at the yearly workshop of the Nano Area of Advance at Chalmers!
2nd of August 2023
Warm welcome to Lei Du who starts as a postdoc in our group today! Lei will start working on a Wallenberg project on nonlinear optomechanics in collaboration between theory groups and the experimental group of Witlef Wieczorek.
21st of June
Congratulations to Lara Ortmanns, who successfully defended her PhD today. The thesis was carried out in a cotutoring agreement between Chalmers and the RWTH Aachen in Germany and has the title: From 2d-van der Waals magnets to superconductor hybrid device.
4th of May 2023
Happy to announce that Janine was awarded an ERC consolidator grant! Looking forward to start the project NanoRecycle, dealing with energy conversion processes in nanoelectronic and hybrid devices!
1st November 2022:
Welcome Jens! Jens Schulenborg will work as a postdoc in the group during the coming months. He will focus on dynamics of strongly interacting quantum dots, exploiting a fermionic dissipative symmetry that we have previously discovered.
21st October 2022:
Congratulations!!!! Ludovico Tesser defended his Licenciate thesis Fluctuations and nonequilibrium thermodynamics in electronic nanosystems today. Patrick Potts from University of Basel was the opponent of the defense. The published thesis can be found here.
August 2022:
Our paper arXiv:2201.09553, a collaboration with the experimental group of Christian Glattli in Saclay, has now been accepted in Nature communications!
August 2022:
The News part of this homepage is finally up and running!
Recent Research Highlights
Out-of-Equilibrium Fluctuation-Dissipation Bounds
Ludovico Tesser, Janine Splettstoesser
We prove a general inequality between the charge current and its fluctuations valid for any non-interacting coherent electronic conductor and for any stationary out-of-equilibrium condition, thereby going beyond established fluctuation-dissipation relations. The developed fluctuation-dissipation bound saturates at large temperature bias and reveals additional insight for heat engines, since it limits the output power by power fluctuations. It is valid when the thermodynamic uncertainty relations break down due to quantum effects and provides stronger constraints close to thermovoltage.
arXiv:2309.17422 (2023), accepted for publication in Phys. Rev. Lett.
Two-particle time-domain interferometry in the fractional quantum Hall effect regime.
I. Taktak, M. Kapfer, J. Nath, P. Roulleau, M. Acciai, J. Splettstoesser, I. Farrer, D. A. Ritchie, D. C. Glattli
Quasi-particles are elementary excitations of condensed matter quantum phases. Demonstrating that they keep quantum coherence while propagating is a fundamental issue for their manipulation for quantum information tasks. Here, we consider anyons, the fractionally charged quasi-particles of the Fractional Quantum Hall Effect occurring in two-dimensional electronic conductors in high magnetic fields. They obey anyonic statistics, intermediate between fermionic and bosonic. Surprisingly, anyons show large quantum coherence when transmitted through the localized states of electronic Fabry-Pérot interferometers, but almost no quantum interference when transmitted via the propagating states of Mach-Zehnder interferometers. Here, using a novel interferometric approach, we demonstrate that anyons do keep quantum coherence while propagating. Performing two-particle time-domain interference measurements sensitive to the two-particle Hanbury Brown Twiss phase, we find 53 and 60% visibilities for anyons with charges e/5 and e/3. Our results give a positive message for the challenge of performing controlled quantum coherent braiding of anyons.
Readout of quantum screening effects using a time-dependent probe
Nastaran Dashti, Matteo Acciai, Sara Kheradsoud, Maciej Misiorny, Peter Samuelsson, and Janine Splettstoesser
In voltage- and temperature-biased coherent conductors quantum screening effects occur if the conductor’s transmission is energy dependent. Here, we show that an additional ac-driven terminal can act as a probe for a direct readout of such effects, hitherto unexplored. We find that screening of charges induced by the static biases impacts already their standard linear thermoelectric response coefficients due to nonlinear effects when accounting for the frequency of the time-dependent driving. Those effects should be observable under realistic experimental conditions and can literally be switched on and off with the ac driving.
General bounds on zero-current shot noise
Jakob Eriksson, Matteo Acciai, Ludovico Tesser, and Janine Splettstoesser
We investigate the charge and heat electronic noise in a generic two-terminal mesoscopic conductor in the absence of the corresponding charge and heat currents. Despite these currents being zero, shot noise is generated in the system. We show that, irrespective of the conductor’s details and the specific nonequilibrium conditions, the charge shot noise never exceeds its thermal counterpart, thus establishing a general bound. Such a bound does not exist in the case of heat noise, which reveals a fundamental difference between charge and heat transport under zero-current conditions.
