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

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)].

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.

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.

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