Thermodynamic constraints on noise
Doktorsavhandling, 2025
The recent progress in nanotechnology has allowed the fabrication of smaller and smaller devices.
On the one hand, this development allows to fit more of such devices on a chip, improving its performance.
On the other hand, as the size of the device decreases, new phenomena emerge, such as quantum effects and sizable fluctuations.
Indeed, when the size of the device is comparable with the coherence length, the quantum nature of particles cannot be neglected. Furthermore, the smaller a device is, the more it is affected by random changes in one of its few components, leading to fluctuations and noise that are comparable with the average quantities.
While these phenomena pose new challenges, they also offer new opportunities both in terms of understanding the underlying physical system, and of realizing new devices that exploit such phenomena.
This thesis studies, from a theoretical perspective, the noise in such nanodevices where both quantum effects and fluctuations play an important role.
While noise has already been investigated for systems at thermodynamic equilibrium, most devices need to operate out of equilibrium in order to be useful.
Here we show that such out-of-equilibrium conditions set constraints on how large or how small the noise can be, and how these constraints affect the precision of the device.
The appended papers discuss these constraints starting from a quantum transport perspective, and study the impact they have on the performance of thermal machines.
In this thesis we do not follow the same route. Instead, we first introduce out-of-equilibrium fluctuations in the context of quantum stochastic thermodynamics, and then use this framework to describe transport.
This different approach aims at providing a broader perspective on the constraints on noise found in the appended papers, putting them into context with previously known results such as the fluctuation-dissipation theorem, and both thermodynamic and kinetic uncertainty relations.
On the one hand, this development allows to fit more of such devices on a chip, improving its performance.
On the other hand, as the size of the device decreases, new phenomena emerge, such as quantum effects and sizable fluctuations.
Indeed, when the size of the device is comparable with the coherence length, the quantum nature of particles cannot be neglected. Furthermore, the smaller a device is, the more it is affected by random changes in one of its few components, leading to fluctuations and noise that are comparable with the average quantities.
While these phenomena pose new challenges, they also offer new opportunities both in terms of understanding the underlying physical system, and of realizing new devices that exploit such phenomena.
This thesis studies, from a theoretical perspective, the noise in such nanodevices where both quantum effects and fluctuations play an important role.
While noise has already been investigated for systems at thermodynamic equilibrium, most devices need to operate out of equilibrium in order to be useful.
Here we show that such out-of-equilibrium conditions set constraints on how large or how small the noise can be, and how these constraints affect the precision of the device.
The appended papers discuss these constraints starting from a quantum transport perspective, and study the impact they have on the performance of thermal machines.
In this thesis we do not follow the same route. Instead, we first introduce out-of-equilibrium fluctuations in the context of quantum stochastic thermodynamics, and then use this framework to describe transport.
This different approach aims at providing a broader perspective on the constraints on noise found in the appended papers, putting them into context with previously known results such as the fluctuation-dissipation theorem, and both thermodynamic and kinetic uncertainty relations.
limits on precision
quantum transport
quantum thermodynamics
out-of-equilibrium noise
Kollektorn
Opponent: Gabriel Landi, Rochester University, USA
Författare
Ludovico Tesser
Chalmers, Mikroteknologi och nanovetenskap, Tillämpad kvantfysik
Out-of-Equilibrium Fluctuation-Dissipation Bounds
Physical Review Letters,;Vol. 132(2024)
Artikel i vetenskaplig tidskrift
Constraints between entropy production and its fluctuations in nonthermal engines
Physical Review B,;Vol. 109(2024)
Artikel i vetenskaplig tidskrift
Charge, spin, and heat shot noises in the absence of average currents: Conditions on bounds at zero and finite frequencies
Physical Review B,;Vol. 107(2023)
Artikel i vetenskaplig tidskrift
General Bounds on Electronic Shot Noise in the Absence of Currents
Physical Review Letters,;Vol. 127(2021)
Artikel i vetenskaplig tidskrift
L. Tesser, M. Acciai, C. Spånslätt, I. Safi, J. Splettstoesser: Thermodynamic and energetic constraints on out-of-equilibrium tunneling rates
D. Palmqvist, L. Tesser, J. Splettstoesser: Kinetic uncertainty relations for quantum transport
Thermodynamics was originally developed to study and optimize the steam engines that powered the industrial revolution.
Since then, technology has taken many steps forward, and today electrical circuits and nanotechnology play a central role in modern society.
These advancements allow us to study and realize devices at ever-smaller scales.
In these tiny devices fluctuations--or noise-- are significant and comparable to the average values, and quantum effects may also play an important role.
On the one hand, this noise makes the behavior of the system less predictable and precise than their macroscopic counterparts.
However, on the other hand, these features also give additional insights into the inner mechanisms governing the device and open up opportunities for the development of new technologies.
Thermodynamics has therefore evolved to account for these phenomena and their impact on performance.
In this thesis we study the noise in small-scale devices operating out of equilibrium.
For instance, these devices may connect to a hot and a cold reservoir to produce power, just like the steam engine, but they are also subject to sizable fluctuations and quantum effects.
Even under such out-of-equilibrium conditions, we show that the noise fulfills constraints, which reveal how precise these devices can be.
Since then, technology has taken many steps forward, and today electrical circuits and nanotechnology play a central role in modern society.
These advancements allow us to study and realize devices at ever-smaller scales.
In these tiny devices fluctuations--or noise-- are significant and comparable to the average values, and quantum effects may also play an important role.
On the one hand, this noise makes the behavior of the system less predictable and precise than their macroscopic counterparts.
However, on the other hand, these features also give additional insights into the inner mechanisms governing the device and open up opportunities for the development of new technologies.
Thermodynamics has therefore evolved to account for these phenomena and their impact on performance.
In this thesis we study the noise in small-scale devices operating out of equilibrium.
For instance, these devices may connect to a hot and a cold reservoir to produce power, just like the steam engine, but they are also subject to sizable fluctuations and quantum effects.
Even under such out-of-equilibrium conditions, we show that the noise fulfills constraints, which reveal how precise these devices can be.
Ämneskategorier (SSIF 2025)
Nanoteknisk elektronik
Ämneskategorier (SSIF 2011)
Nanoteknik
ISBN
978-91-8103-141-6
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5599
Utgivare
Chalmers
Kollektorn
Opponent: Gabriel Landi, Rochester University, USA