Sebastian Deffner

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 ...

The amazing Prof. Nakalembe taking the TED stage: www.ted.com/talks/cather...

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...

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...

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...

journals.aps.org/pra/abstract...

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...

New preprint: employing NISQ to verify the tenets of Quantum Darwinism

arxiv.org/abs/2601.05350

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...

Does it matter thermodynamically how to code your algorithm? On quantum annealers it matters a lot:

arxiv.org/abs/2601.04402

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...

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.

Happy 40th Birthday @epljournal.bsky.social

iopscience.iop.org/article/10.1...

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...

Fluctuation theorems for autonomous work | PNAS www.pnas.org/doi/10.1073/...

More than anything else this seems to be another indication of the unprecedented opportunity for other countries to poach and recruit US-based academics.

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

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...

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 ...

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

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.

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.

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...

Yup! 75% of us are considering leaving (/made plans to leave/already left) 😢 🧪

www.pbs.org/newshour/sho...

Quantum Science Institute @umbc.bsky.social representation at the Quantum Leap Career Nexus!

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...

YouTube video by UMBCtube Quantum on Track: Quantum Computing for Urban Train Scheduling

Train scheduling goes quantum feat. Dr. Emery Doucet and Reece Robertson:

www.youtube.com/watch?v=xWKR...

www.nature.com/articles/s41...

Do you want to do a postdoc with me? 10 days left to apply!

apply.interfolio.com/172719

Couldn’t agree more!

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...

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

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...

New preprint: Quantum thermodynamics of Gross-Pitaevskii qubits

arxiv.org/abs/2510.12599

New letter in Quantum Science and Technology @iopp-quantum.bsky.social with Josey Stevens:

iopscience.iop.org/article/10.1...

Quantum On Track: UMBC Researchers Demonstrate Feasibility Of Using Quantum Devices To Manage Urban Train Scheduling, Using A Baltimore Transit Line As A Model A new study led by UMBC researchers—and focused on Baltimore’s Light RailLink, a hybrid tram-rail network sharing roads with cars inside Baltimore City—harnesses quantum computing to address the chall...

umbc.edu/stories/quan...

Congratulations Dr. Son!

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.

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

Suppressing excitations in the nonlinear Landau-Zener model
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

News: opening in my group for a Postdoc coming soon. Research: quantum information scrambling.