Welcome to the Quantum Thermodynamics Group

The theory of thermodynamics was a driving force in the industrial revolution. By enabling the development of devices such as steam engines and refrigerators, it had a tremendous impact. At the nanoscale, where systems experience fluctuations and quantum effects, our thermodynamic understanding is still being expanded. Our group is a part of this exciting development which promises to produce important contributions to emerging nano- and quantum-technologies.

New Publications

Probabilistically violating the first law of thermodynamics in a quantum heat engine

first law violations

SciPost Phys. 12, 168 (2022)

Fluctuations of thermodynamic observables, such as heat and work, contain relevant information on the underlying physical process. These fluctuations are however not taken into account in the traditional laws of thermodynamics. While the second law is extended to fluctuating systems by the celebrated fluctuation theorems, the first law is generally believed to hold even in the presence of fluctuations. Here we show that in the presence of quantum fluctuations, also the first law of thermodynamics may break down. To illustrate our results, we provide a detailed case-study of work and heat fluctuations in a quantum heat engine based on a circuit QED architecture.

A thermodynamically consistent Markovian master equation beyond the secular approximation

Harmonic oscillators coupled to thermal baths

New J. Phys. 23, 123013 (2021)

Markovian master equations provide a versatile tool for describing open quantum systems when memory effects of the environment may be neglected. As these equations are of an approximate nature, they often do not respect the laws of thermodynamics when no secular approximation is performed in their derivation. Here we introduce a Markovian master equation that is thermodynamically consistent and provides an accurate description whenever memory effects can be neglected. Our results enable a thermodynamically consistent description of a variety of systems where the secular approximation breaks down.

Efficient and continuous microwave photoconversion in hybrid cavity-semiconductor nanowire double quantum dot diodes

Photodetector

Nat. Commun. 12, 5130 (2021)

Press

Converting incoming photons to electrical current is the key operation principle of optical photodetectors and it enables a host of emerging quantum information technologies. Here we demonstrate how microwave photons can be efficiently and continuously converted to electrical current in a high-quality, semiconducting nanowire double quantum dot resonantly coupled to a cavity. In our photodiode device, an absorbed photon gives rise to a single electron tunneling through the double dot, with a conversion efficiency reaching 6%.

Violating the thermodynamic uncertainty relation in the three-level maser

Scovil and Schulz-duBois maser

Phys. Rev. E 104, L012103 (2021)

The Thermodynamic Uncertainty Relation (TUR), a trade-off between power, efficiency, and low fluctuations, can be violated in the prototypical Scovil and Schulz-duBois maser. Comparing this maser to a classical analogue sheds light onto the relation between TUR violations and quantum coherence. Our results indicate that the coherent nature of the dynamics responsible for TUR violations is not encoded in the off-diagonal elements of the steady state density matrix.

News

01 July

Saulo Moreira from Lund University presented a joint work with Patrick on the thermodynamics of a quantum dot coupled to a finite sized reservoir at the Quantum Thermodynamics Conference 2022. Find the video here.

15 March

Aaron Daniel started to work on his master thesis in our group. Welcome!

16 February

Patrick Potts was awarded the IOP Trusted Reviewer Status.

31 January - 04 February
07 December 2021

Patrick Potts is featured in an SNI Insight article.

01 December 2021

Vardan Kaladzhyan started a Postdoc in the Quantum Thermodynamics Group. Welcome!

15 October 2021

Matteo Brunelli started a Postdoc in the Quantum Thermodynamics Group. Welcome!

15 September 2021

Kacper Prech started his PhD in the Quantum Thermodynamics Group. Welcome!

23 - 27 August

Patrick Potts lectured on Thermodynamics in Superconducting Circuits at the Quantum Thermodynamics summer school 2021. See the lecture here: part 1, part 2.

01 August 2021

Marcelo Janovitch started his PhD in the Quantum Thermodynamics Group. Welcome!

27 May 2021

Patrick Potts talked about Quantum Thermodynamics at a QSIT Seminar.

01 May 2021

The Quantum Thermodynamics Group was started.