Sebastian Deffner

Dec 11, 2024 | link.aps.org | Sebastian Deffner |Emery Doucet

A classical understanding of measurement is entirely sufficient to explain the everyday world. Given that the Universe is fundamentally quantum, this is somewhat surprising. There must be some mechanism by which classical reality is an emergent property of the quantum Universe. A well-developed framework to explain this emergence is quantum Darwinism.

Aug 5, 2024 | link.aps.org | Moallison F. Cavalcante |Eduardo Miranda |Sebastian Deffner

We consider the optimal control of switching on a coupling term between two quantum many-body systems. Specifically, we (i) quantify the energetic cost of establishing a weak junction between two quantum spin-1/2 chains in finite time τ and (ii) identify the energetically optimal protocol to realize it. For linear driving protocols, we find that for long times the excess (irreversible) work scales as τ−η, where η=1,2 or a nonuniversal number depending on the phase of the chains.

Jul 9, 2024 | link.aps.org | Maxwell Aifer |Juzar Thingna |Sebastian Deffner

Quantum synchronization is crucial for understanding complex dynamics and holds potential applications in quantum computing and communication. Therefore, assessing the thermodynamic resources required for finite-time synchronization in continuous-variable systems is a critical challenge. In the present work, we find these resources to be extensive for large systems.

Nov 22, 2023 | mdpi.com | Sebastian Deffner |Paul Duruisseau |Akram Touil

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Nov 17, 2023 | link.aps.org | Kenji J. Maeda |Tharon Holdsworth |Sebastian Deffner |Akira Sone

We study the quantum fluctuation theorem in the one-time measurement (OTM) scheme, where the work distribution of the backward process has been lacking and which is considered to be more informative than the two-time measurement (TTM) scheme. We find that the OTM scheme is the quantum nondemolition TTM scheme, in which the final state is a pointer state of the second measurement whose Hamiltonian is conditioned on the first measurement outcome.