Resetting a many-body interacting spin network from a mixed state to a computational-zero pure state is a fundamental prerequisite for quantum information processing tasks. However, this task is highly nontrivial due to the presence of symmetry based constraints in the system, and therefore remains a challenge both theoretically and experimentally. In this talk, I will present a universal cooling strategy for multi-spin interacting networks. The strategy is based on the collective coupling of the system to an ancilla spin that intermittently transfers part of its entropy to an ultracold bath. We show that this approach overcomes symmetry-imposed constraints (including graph symmetry, angular momentum symmetry, and spectral symmetry) that hinder the cooling process. In particular, we demonstrate that a specific sequence of alternating, non-commuting system–ancilla interaction Hamiltonians can break these symmetry constraints and enable the network to approach the desired pure state.

Reference: Collective purification of interacting quantum networks beyond symmetry constraints, Sur, S. et al., npj Quantum Inf (2026) https://www.nature.com/articles/s41534-026-01228-9.