Sebastian Deffner
@quthermo.bsky.social
Father of twins, theoretical physicist, quantum thermodynamicist;
Thermodynamics and control of information in complex quantum systems.
quthermo.umbc.edu
Thermodynamics and control of information in complex quantum systems.
quthermo.umbc.edu
Does it matter thermodynamically how to code your algorithm? On quantum annealers it matters a lot:
arxiv.org/abs/2601.04402
arxiv.org/abs/2601.04402
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...
arxiv.org
January 9, 2026 at 3:46 PM
Does it matter thermodynamically how to code your algorithm? On quantum annealers it matters a lot:
arxiv.org/abs/2601.04402
arxiv.org/abs/2601.04402
Reposted by Sebastian Deffner
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...
scirate.com/arxiv/2601.0...
January 9, 2026 at 10:29 AM
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...
scirate.com/arxiv/2601.0...
Reposted by Sebastian Deffner
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.
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.
January 5, 2026 at 4:27 AM
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.
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.
Fluctuation theorems for autonomous work | PNAS www.pnas.org/doi/10.1073/...
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...
www.pnas.org
December 13, 2025 at 12:36 AM
Fluctuation theorems for autonomous work | PNAS www.pnas.org/doi/10.1073/...
Reposted by Sebastian Deffner
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
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
December 5, 2025 at 5:54 PM
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
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
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...
New publication in @epljournal.bsky.social
iopscience.iop.org/article/10.1...
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iopscience.iop.org
November 26, 2025 at 2:04 PM
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...
New publication in @epljournal.bsky.social
iopscience.iop.org/article/10.1...
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/abs/2511.15691
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 ...
arxiv.org
November 20, 2025 at 2:41 PM
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/abs/2511.15691
Reposted by Sebastian Deffner
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.
For foreign professionals, the crackdown has meant new levels of anguish and fear.
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.
www.washingtonpost.com
November 18, 2025 at 6:00 PM
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.
For foreign professionals, the crackdown has meant new levels of anguish and fear.
Reposted by Sebastian Deffner
Yup! 75% of us are considering leaving (/made plans to leave/already left) 😢 🧪
www.pbs.org/newshour/sho...
www.pbs.org/newshour/sho...
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...
www.pbs.org
November 2, 2025 at 3:45 AM
Yup! 75% of us are considering leaving (/made plans to leave/already left) 😢 🧪
www.pbs.org/newshour/sho...
www.pbs.org/newshour/sho...
Quantum Science Institute @umbc.bsky.social representation at the Quantum Leap Career Nexus!
October 28, 2025 at 6:31 PM
Quantum Science Institute @umbc.bsky.social representation at the Quantum Leap Career Nexus!
Reposted by Sebastian Deffner
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...
www.nature.com/articles/s41...
October 22, 2025 at 11:58 AM
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...
www.nature.com/articles/s41...
Train scheduling goes quantum feat. Dr. Emery Doucet and Reece Robertson:
www.youtube.com/watch?v=xWKR...
www.nature.com/articles/s41...
www.youtube.com/watch?v=xWKR...
www.nature.com/articles/s41...
Quantum on Track: Quantum Computing for Urban Train Scheduling
YouTube video by UMBCtube
www.youtube.com
October 21, 2025 at 4:58 PM
Train scheduling goes quantum feat. Dr. Emery Doucet and Reece Robertson:
www.youtube.com/watch?v=xWKR...
www.nature.com/articles/s41...
www.youtube.com/watch?v=xWKR...
www.nature.com/articles/s41...
Apply - Interfolio
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apply.interfolio.com
October 21, 2025 at 12:53 PM
Couldn’t agree more!
Is it just me that finds it weird how ingrained it is in science that research groups identify as "The PI's-last-name group" as if their research & research interests were entirely determined by the PI? To me this feels unnecessarily adhering to authority and fostering cults centered around PIs.
October 16, 2025 at 11:29 AM
Couldn’t agree more!
New preprint: Metrological approach to the emergence of classical objectivity
Anthony Kiely, Diana A. Chisholm, Akram Touil, Sebastian Deffner, Gabriel Landi, and Steve Campbell
arxiv.org/abs/2510.12313
Anthony Kiely, Diana A. Chisholm, Akram Touil, Sebastian Deffner, Gabriel Landi, and Steve Campbell
arxiv.org/abs/2510.12313
Metrological approach to the emergence of classical objectivity
We present a precise characterization of the onset of classicality that combines the formalism of quantum Darwinism with the tools from quantum metrology. We show that the quantum Fisher information p...
arxiv.org
October 15, 2025 at 5:44 PM
New preprint: Metrological approach to the emergence of classical objectivity
Anthony Kiely, Diana A. Chisholm, Akram Touil, Sebastian Deffner, Gabriel Landi, and Steve Campbell
arxiv.org/abs/2510.12313
Anthony Kiely, Diana A. Chisholm, Akram Touil, Sebastian Deffner, Gabriel Landi, and Steve Campbell
arxiv.org/abs/2510.12313
New letter in Quantum Science and Technology @iopp-quantum.bsky.social with Josey Stevens:
iopscience.iop.org/article/10.1...
iopscience.iop.org/article/10.1...
Hamiltonian quantum gates-energetic advantage from entangleability - IOPscience
Hamiltonian quantum gates-energetic advantage from entangleability, Stevens, Josey, Deffner, Sebastian
iopscience.iop.org
October 14, 2025 at 4:26 PM
New letter in Quantum Science and Technology @iopp-quantum.bsky.social with Josey Stevens:
iopscience.iop.org/article/10.1...
iopscience.iop.org/article/10.1...
Reposted by Sebastian Deffner
Pauses to some US graduate programmes have led universities in several countries to launch initiatives to entice would-be PhD students
go.nature.com/46AqorN
go.nature.com/46AqorN
These nations are wooing PhD students amid US funding uncertainties
Pauses to some US graduate programmes have led universities in several countries to launch initiatives to entice would-be PhD students.
go.nature.com
September 9, 2025 at 11:36 AM
Pauses to some US graduate programmes have led universities in several countries to launch initiatives to entice would-be PhD students
go.nature.com/46AqorN
go.nature.com/46AqorN
Suppressing excitations in the nonlinear Landau-Zener model
doi.org/10.1209/0295... via @ioppublishing.bsky.social
doi.org/10.1209/0295... via @ioppublishing.bsky.social
Suppressing excitations in the nonlinear Landau-Zener model - IOPscience
Suppressing excitations in the nonlinear Landau-Zener model, Deffner, Sebastian, Campbell, Steve
doi.org
September 8, 2025 at 10:49 PM
Suppressing excitations in the nonlinear Landau-Zener model
doi.org/10.1209/0295... via @ioppublishing.bsky.social
doi.org/10.1209/0295... via @ioppublishing.bsky.social
Opening for postdoctoral researcher! Do you have a PhD in Theoretical Physics? Are you interested to work with me on quantum information scrambling? Then this position might be for you:
apply.interfolio.com/172719
apply.interfolio.com/172719
Apply - Interfolio
{{$ctrl.$state.data.pageTitle}} - Apply - Interfolio
apply.interfolio.com
September 2, 2025 at 4:29 PM
Opening for postdoctoral researcher! Do you have a PhD in Theoretical Physics? Are you interested to work with me on quantum information scrambling? Then this position might be for you:
apply.interfolio.com/172719
apply.interfolio.com/172719