Purity enhancement from athermaility enhancement

Purity enhancement from athermaility enhancement

Seminar author:Benjamin Stratton

Event date and time:10/09/2025 03:00:pm

Event location:Seminars Room, GIQ

Event contact:

Purity is a key resource in quantum technologies; it is therefore natural to want to increase the amount one has. Here, we develop a purity enhancement protocol by considering the related, but distinct task of athermality enhancement.  Specifically, we consider the tasks of unitarily cooling a thermal qubit given access to n-other thermal qubits, presenting an algorithm that both generates the optimal cooling dynamics and calculates the amount of cooling achievable. We then show how the algorithm can be generalised into a purity enhancement protocol for arbitrary states. It is then discussed how this relates to the framework of informational non-equilibrium concentration — which asks by how much we can increase the local informational non-equilibrium given an initial product state ρ ⊗ ρ and access to global unitary operations.

The talk is based on the following pieces of work: https://arxiv.org/abs/2506.10059, https://arxiv.org/abs/2409.12759.