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Sebastian Deffner

@quthermo.bsky.social
270 followers 429 following 67 posts

Father of twins, theoretical physicist, quantum thermodynamicist; Thermodynamics and control of information in complex quantum systems. quthermo.umbc.edu

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Sebastian Deffner @quthermo.bsky.social · 23/09/2026
physics.umbc.edu/home/news/po...
physics.umbc.edu
From Langenberg Award to Journal Publication: Gregory Behrendt's Research on Heat Engine Efficiency
Every undergraduate student has learned that the maximal efficiency any heat engine can achieve is given by the Carnot efficiency, which describes the Carnot cycle and which is independent of the work...
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Sebastian Deffner @quthermo.bsky.social · 20/09/2026
New paper with Greg Behrendt: www.mdpi.com/1099-4300/28...
mdpi.com
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Sebastian Deffner @quthermo.bsky.social · 18/09/2026
New preprint: arxiv.org/abs/2609.20757
arxiv.org
Procrastinating einselection in non-Markovian quantum dynamics
Among the processes governed by open-system and dissipative quantum dynamics, environment-induced superselection, or einselection, is particularly foundational, since it describes the formation of a p...
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Sebastian Deffner @quthermo.bsky.social · 13/08/2026
A little while ago, I asked a question to which I thought I really should now the answer....but I didn't. Given a particular heat engine cycle, what is the optimal working medium that gives the highest efficiency? New preprint by Gregory Behrendt with the answer: arxiv.org/abs/2608.11966
arxiv.org
Ideal heat engine cycles at maximal efficiency -- the ideal gas and beyond
Given a particular heat engine cycle, what is the optimal working medium that results in the highest efficiency? While one might jump to the conclusion that it must surely be the ideal gas, the situat...
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Sebastian Deffner @quthermo.bsky.social · 10/08/2026
physicstoday.aip.org/features/the...
physicstoday.aip.org
The decline in physics bachelor’s degrees: Contributors and consequences
As higher-education programs compete for a shrinking pool of students, departments must better communicate the value that a physics major brings.
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Sebastian Deffner @quthermo.bsky.social · 16/07/2026
iopscience.iop.org/article/10.1...
iopscience.iop.org
From compatibility of measurements to exploring quantum Darwinism on NISQ
From compatibility of measurements to exploring quantum Darwinism on NISQ, Doucet, Emery, Deffner, Sebastian
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Sebastian Deffner @quthermo.bsky.social · 10/07/2026
New preprint: arxiv.org/abs/2607.07988
arxiv.org
Procrustes Tomography -- reconstructing noisy quantum channels made easy
What is the most expensive part of quantum device characterization? Clearly, the answer is quantum process tomography. However, especially for noisy intermediate-scale quantum (NISQ) computers, a comp...
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Sebastian Deffner @quthermo.bsky.social · 27/05/2026
New paper in New Journal of Physics @ioppublishing.bsky.social @iopp-quantum.bsky.social: We show that the precise way you code your quantum algorithm for quantum annealers can have tremendous thermodynamic consequences. With @reecejrobertson.bsky.social iopscience.iop.org/article/10.1...
iopscience.iop.org
Thermodynamic significance of QUBO encoding on quantum annealers
Thermodynamic significance of QUBO encoding on quantum annealers, Doucet, Emery, Mzaouali, Zakaria, Robertson, Reece, Gardas, Bartłomiej, Deffner, Sebastian, Domino, Krzysztof
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Sebastian Deffner @quthermo.bsky.social · 22/05/2026
Congratulations to Maggie Williams for receiving her Master of Science in Physics from UMBC!! And as perfect timing goes, here is also her first published paper now available in Journal of Nonequilibrium Thermodynamics: www.degruyterbrill.com/document/doi...
degruyterbrill.com
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Sebastian Deffner @quthermo.bsky.social · 11/05/2026
Last chance to sign up for "Natural and Engineered Complex Quantum Systems Workshop at UMBC" forms.gle/qrNbVKFjsUGb...
forms.gle
Registration: Natural and Engineered Complex Quantum Systems Workshop at UMBC
Registration for the workshop held at UMBC on May 26th and 27th 2026
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Reposted by Sebastian Deffner
EPL (Europhysics Letters) @epljournal.bsky.social · 07/05/2026
EPL celebrates its 40th anniversary! 🎉 To celebrate, we launch a series of 40th Anniversary Highlights, written by our Editor-in-Chief Dr Richard Blythe and our three Deputy Editors, and revisiting key papers published in EPL.
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Sebastian Deffner @quthermo.bsky.social · 07/05/2026
Implementing quantum error correction is generally expected to be absolutely crucial in achieving fault tolerance. However, bigger is not always better! And the specific implementation matters a lot! @joseystevens.bsky.social exploring the energy-error tradeoff: arxiv.org/abs/2605.04329
arxiv.org
Energy-error tradeoff in encoding quantum error correction
While it has been widely recognized that genuine quantum advantage for practical problems might only be achieved with fault-tolerant quantum computers, it is still not entirely clear whether the requi...
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APS DSNP @aps-dsnp.bsky.social · 07/05/2026
📌 We are thrilled to host Sidney Redner (Santa Fe Institute) for our next klogW seminar on May 12 at 12PM EST on "First-Passage Processes with Applications to Resetting-Driven Optimization, Wealth Sharing, and Forest Fires" 🔥 Register here: engage.aps.org/dsnp/resourc...
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Sebastian Deffner @quthermo.bsky.social · 30/04/2026
New preprint celebrating Amir O. Caldeira's contributions to the understanding of Quantum Brownian Motion: arxiv.org/abs/2604.26524
arxiv.org
Over forty years of research towards the understanding of Quantum Brownian Motion -- the contributions of A. O. Caldeira
This article presents a brief account of Amir O. Caldeira's contributions to the theory of quantum Brownian motion. Motivated by its importance, we outline the description of Brownian motion in the qu...
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Sebastian Deffner @quthermo.bsky.social · 28/04/2026
New preprint: Quantum speed limit for measurement probabilities arxiv.org/abs/2604.23160
arxiv.org
Quantum speed limit for measurement probabilities
Any protocol to process quantum information has to conclude with a measurement, aimed at producing a specific set of probabilities of measurement outcomes. In this work, we investigate the time, energ...
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Katie Mack @astrokatie.com · 23/04/2026
When Einstein developed general relativity the closest thing to a practical application that could even be imagined at the time was a slightly more precise description of where to look for the planet Mercury in the sky, and yet now we’d all be literally lost without it. Anyway: fund basic research.
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Sebastian Deffner @quthermo.bsky.social · 23/04/2026
Undergrad researcher Monty presenting his project on solving PDEs on NISQ advised by @reecejrobertson.bsky.social @umbc.edu
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Sebastian Deffner @quthermo.bsky.social · 22/04/2026
New paper: Quantum speed limit for observables from quantum asymmetry @physreva.bsky.social journals.aps.org/pra/abstract...
journals.aps.org
Quantum speed limit for observables from quantum asymmetry
Quantum asymmetry and coherence are genuinely quantum resources that are essential to realize quantum advantage in information technologies. However, all quantum processes are fundamentally constraine...
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APS DSNP @aps-dsnp.bsky.social · 17/04/2026
📣 We’re kicking off the first klogW seminar of the year! Join us on April 21st at 12PM EST for a talk by Douglas Jerolmack (UPenn) — 2026 APS-DSNP Fellow — presenting "Fragility of Soft Earth Materials" 🌎🌍🌏 Registration link: apsphysics.zoom.us/webinar/regi...
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Sebastian Deffner @quthermo.bsky.social · 08/04/2026
New paper in @physreve.bsky.social: Quantum thermodynamics of Gross-Pitaevskii qubits journals.aps.org/pre/abstract...
journals.aps.org
Quantum thermodynamics of Gross-Pitaevskii qubits
What are the resources that can be leveraged for a thermodynamic device to exhibit genuine quantum advantage? Typically, the answer to this question is sought in quantum correlations. In the present w...
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Sebastian Deffner @quthermo.bsky.social · 08/04/2026
Congrats to QSI Graduate Fellow @reecejrobertson.bsky.social for winning UMBC's 3MT competition today! Next stop, Regionals! gears.umbc.edu/3mt/
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APS DSNP @aps-dsnp.bsky.social · 26/03/2026
📣 DSNP Early-Career Spotlight: Megan Engel from University of Calgary! Her research focuses on molecular motors' efficiency—and how to apply these principles to bio-nanotechnology. Check out the interview below! Want to suggest who to feature next? Email us at gsnpsocialmedia@gmail.com
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APS DSNP @aps-dsnp.bsky.social · 16/03/2026
📣 After a fantastic Squishy Sunday event, the APS Global Physics Summit 2026 has officially started! Check out the DSNP session schedule below. Come say hi at the DSNP table and get your members-only T-shirt! #APSSummit2026 #GlobalPhysicsSummit #DSNP #StatisticalPhysics #NonlinearPhysics #APS
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APS DSNP @aps-dsnp.bsky.social · 14/03/2026
🎉 30 years of Statistical & Nonlinear Physics — and we're just getting started! To mark the transition from APS G to D, @physreve.bsky.social have highlighted the most influential papers that drew the map of the field. 📖 journals.aps.org/over-30-years #StatisticalPhysics #DSNP #Physics
journals.aps.org
Over 30 years of Statistical and Nonlinear Physics in _Physical Review E_
APS Division of Statistical and Nonlinear Physics and <em>Physical Review E</em> review over 30 years of research in the division’s areas.
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APS DSNP @aps-dsnp.bsky.social · 13/03/2026
Excited for #APSSummit26? We are too! Come join us, we’re looking for volunteers! @apsphysics.bsky.social #StatsPhys #NonlinearPhys Details 👇
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APS DSNP @aps-dsnp.bsky.social · 12/03/2026
We’re delighted to share a new editorial in @physreve.bsky.social (PRE) on the DSNP Dissertation Award in #Statistical & #Nonlinear Physics, marking the inaugural year of PRE sponsorship. Congratulations to the winner, 𝐉𝐨𝐧𝐚𝐬 𝐕𝐞𝐞𝐧𝐬𝐭𝐫𝐚, from UvA 🎉 Read more: journals.aps.org/pre/abstract...
journals.aps.org
Editorial: DSNP Dissertation Award 2025 -- Pushing the limits of active metamaterials
The DSNP Dissertation Award Selection Committee presents the 2025 Award sponsored by Physical Review E.
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Sebastian Deffner @quthermo.bsky.social · 12/03/2026
At the upcoming Global Physics Summit in Denver, @aps-dsnp.bsky.social will be celebrating our advancement from Topical Group to Division! To kick the party off, here is a collection of highlights published in @physreve.bsky.social: journals.aps.org/over-30-years
journals.aps.org
Over 30 years of Statistical and Nonlinear Physics in _Physical Review E_
APS Division of Statistical and Nonlinear Physics and <em>Physical Review E</em> review over 30 years of research in the division’s areas.
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The Hilbert Space Post @hilbertspacepost.bsky.social · 05/03/2026
A variational quantum algorithm is implemented on IonQ hardware to prepare Gibbs states of the transverse-field Ising model, with fidelities evaluated via state tomography. @reecejrobertson.bsky.social, @quthermo.bsky.social arxiv.org/abs/2603.03801
arxiv.org
Variational Gibbs State Preparation on Trapped-Ion Devices
We implement a variational quantum algorithm for Gibbs state preparation of a transverse-field Ising model on IonQ's quantum computers. To this end, we train the variational parameters via classical s...
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Sebastian Deffner @quthermo.bsky.social · 05/03/2026
What are NISQ computers good for? Well, possibly many things. But definitely for the preparation of Gibbs states: arxiv.org/abs/2603.03801
arxiv.org
Variational Gibbs State Preparation on Trapped-Ion Devices
We implement a variational quantum algorithm for Gibbs state preparation of a transverse-field Ising model on IonQ's quantum computers. To this end, we train the variational parameters via classical s...
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Jake Xuereb @curlyqubit.bsky.social · 04/03/2026
The Qalypso School on Quantum Science in Malta returns for its 3rd edition Aug 31 - Sep 4 this year! 🏖️ We have a great line up of lecturers covering Quantum Optimisation, Quantum Thermodynamics and Quantum Gibbs Sampling. Pre-registrations opens today at forms.gle/3NkMJ3Br9V8b... Do Share!
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Sebastian Deffner @quthermo.bsky.social · 30/01/2026
The amazing Prof. Nakalembe taking the TED stage: www.ted.com/talks/cather...
ted.com
Why can't we better prepare for extreme weather?
Thanks to advanced technology, we can now see droughts and crop failures months before they hit. So why are millions of people still going hungry? TED Fellow Catherine Nakalembe, director of the NASA ...
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Reposted by Sebastian Deffner
Reece Robertson @reecejrobertson.bsky.social · 29/01/2026
New paper on #QuantumComputing emulation just posted to @ieeexplore.bsky.social! I was thrilled to share this work at the @ieeeorg.bsky.social #CASCON2025 conference last November. The project @github.com was awarded an IEEE Research Object Reviewed Badge. ieeexplore.ieee.org/document/113...
ieeexplore.ieee.org
Introducing UNIQuE: The Unconventional Noiseless Intermediate Quantum Emulator
We implement an open-source quantum computing emulator that includes arithmetic operations, the quantum Fourier transform, and quantum phase estimation. The emulator provides significant savings in bo...
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Sebastian Deffner @quthermo.bsky.social · 17/01/2026
journals.aps.org/pra/abstract...
journals.aps.org
Quantum speed limit for the out-of-time-ordered correlator from an open-system perspective
A quantum speed limit for the decay of out-of-time-ordered correlators is established by interpreting information scrambling in a closed quantum system as effective decoherence, relating the scramblin...
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Sebastian Deffner @quthermo.bsky.social · 12/01/2026
New preprint: employing NISQ to verify the tenets of Quantum Darwinism arxiv.org/abs/2601.05350
arxiv.org
From compatibility of measurements to exploring Quantum Darwinism on NISQ
Quantum Darwinism explains how tenets of classical reality, such as objectivity and repeatability, emerge within a quantum universe. As a mathematical framework, Quantum Darwinism also provides guidin...
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Sebastian Deffner @quthermo.bsky.social · 09/01/2026
Does it matter thermodynamically how to code your algorithm? On quantum annealers it matters a lot: arxiv.org/abs/2601.04402
arxiv.org
Thermodynamic significance of QUBO encoding on quantum annealers
Quadratic unconstrained binary optimization (QUBO) is the standard interface to quantum annealers, yet a single constrained task admits many QUBO encodings whose penalty choices reshape the energy lan...
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Jens Eisert @jenseisert.bsky.social · 09/01/2026
To what extent can noisy quantum circuits be classically simulated? And at what point is this no longer true, so that one can hope for a quantum advantage? This is a compelling research question. Here, we suggest frames to do so, extending known Monte Carlo methods. scirate.com/arxiv/2601.0...
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Jens Eisert @jenseisert.bsky.social · 05/01/2026
Do Bose-Hubbard type systems have a speed of sound for particle propagation? scirate.com/arxiv/2601.001… Yes. This work proves a strikingly simple bound of this kind for particle propagation for generalized Bose–Hubbard models defined on general lattices.
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Sebastian Deffner @quthermo.bsky.social · 02/01/2026
Happy 40th Birthday @epljournal.bsky.social iopscience.iop.org/article/10.1...
iopscience.iop.org
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Sebastian Deffner @quthermo.bsky.social · 13/12/2025
Fluctuation theorems for autonomous work | PNAS www.pnas.org/doi/10.1073/...
pnas.org
Fluctuation theorems for autonomous work | PNAS
Classical fluctuation theorems for work have been obtained theoretically, and verified experimentally, within a nonautonomous framework in which wo...
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davidasivak.bsky.social @davidasivak.bsky.social · 05/12/2025
We’re hiring! The Department of Physics @sfuphysics.bsky.social at Simon Fraser U (in beautiful and vibrant Vancouver) seeks applications for an Assistant or Associate Professor in Experimental Biophysics, encompassing all scales of life from molecules to ecosystems. @sfuscience.bsky.social
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Sebastian Deffner @quthermo.bsky.social · 26/11/2025
Do you wonder what Shortcuts to Adiabaticity are really good for? How about correcting quantum gate errors? New publication in @epljournal.bsky.social iopscience.iop.org/article/10.1...
iopscience.iop.org
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Sebastian Deffner @quthermo.bsky.social · 20/11/2025
Have you ever wondered if Maxwell's demon could get dementia? And if so, how would you model it? Wonder no further! Here is the very first manuscript of my grad student Maggie Williams together with Emery Doucet. arxiv.org/abs/2511.15691
arxiv.org
Demon with dementia - the deterioration of information transcription
In introductory biology, aging is typically explained as a result of mutations during the DNA replication process within cells. Upon abstraction, we recognize that cellular aging can be understood as ...
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The Washington Post @washingtonpost.com · 18/11/2025
The Trump administration’s crackdown on legal immigration is making it tougher for doctors, engineers, professors and artists to get permission to work and live in the U.S. For foreign professionals, the crackdown has meant new levels of anguish and fear.
washingtonpost.com
Trump’s immigration crackdown is keeping foreign professionals out
Federal authorities are denying more work visas and green cards, vetting social media posts and applying enhanced scrutiny to foreign employees’ credentials.
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Alison Banwell @alibanwell.bsky.social · 02/11/2025
Yup! 75% of us are considering leaving (/made plans to leave/already left) 😢 🧪 www.pbs.org/newshour/sho...
pbs.org
Top researchers consider leaving U.S. amid funding cuts: 'The science world is ending'
A poll from the journal Nature found that 75% of researchers in the U.S. are considering leaving the country. That includes a man who’s been dubbed the "Mozart of Math." Stephanie Sy examines what’s b...
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Sebastian Deffner @quthermo.bsky.social · 28/10/2025
Quantum Science Institute @umbc.bsky.social representation at the Quantum Leap Career Nexus!
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Jens Eisert @jenseisert.bsky.social · 22/10/2025
This is a manuscript I am particularly happy with. It concerns topics I have been working on for my PhD, entanglement theory, going back to the work of Bennett et al. Yet it still has a fresh flavour, relating the subject to modern developments in quantum computing. www.nature.com/articles/s41...
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Sebastian Deffner @quthermo.bsky.social · 21/10/2025
Train scheduling goes quantum feat. Dr. Emery Doucet and Reece Robertson: www.youtube.com/watch?v=xWKR... www.nature.com/articles/s41...
youtube.com
Quantum on Track: Quantum Computing for Urban Train Scheduling
YouTube video by UMBCtube
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Sebastian Deffner @quthermo.bsky.social · 21/10/2025
Do you want to do a postdoc with me? 10 days left to apply! apply.interfolio.com/172719
apply.interfolio.com
Apply - Interfolio {{$ctrl.$state.data.pageTitle}} - Apply - Interfolio
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Sebastian Deffner @quthermo.bsky.social · 16/10/2025
Couldn’t agree more!
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