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Philippe Faist

@phfaist.bsky.social

713 followers 520 following 49 posts

Tenured senior researcher in quantum information at the Freie Universität Berlin (previously: PhD at ETH Zurich & post-doc at IQIM Caltech) phfaist.com

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Philippe Faist @phfaist.bsky.social · 07/08/2025

Note to self: avoid transparent PNG's in social media posts 😅

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Philippe Faist @phfaist.bsky.social · 07/08/2025

What's the thermal quantum channel good for? Much like how we often replace a complex or unknown quantum microstate by a thermal state in a many-body system [(a)], I'd like to think that we could often replace complex or unknown evolution 𝒰 by the thermal quantum channel [(b)].

Much like how we replace a complex or unknown quantum state by a thermal state in a many-body system [(a)], I'd like to think that we can replace complex or unknown evolution 𝒰 by the thermal quantum channel [(b)]

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Philippe Faist @phfaist.bsky.social · 07/08/2025

The entropy of a channel 𝒩 measures “how thermalizing” 𝒩 is. It quantifies how entropic 𝒩's output is guaranteed to be, for any input state, and even using a reference system as side information. Specifically: if 𝒩 acts on systems A→B and R ≃ A, then S(𝒩) ≡ min_ρ S(B|R), where ρ is any input on AR.

The channel's entropy quantifies how entropic 𝒩's output is guaranteed to be, for any input state, and even using a reference system as side information.

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Philippe Faist @phfaist.bsky.social · 11/06/2025

I’m told the reason they didn’t invite a fifth Nobel prize winner on stage is that they would collapse into a black hole.

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Philippe Faist @phfaist.bsky.social · 15/02/2024

Hard to think of a better place than pretty Les Diablerets to discuss quantum metrology with other metrology enthusiasts!

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