Universal cooling of quantum systems via randomized measurements

Understand

Designing cooling protocols is believed to require knowledge of the system spectrum.

• In contrast, cooling in nature occurs whenever the system is coupled to a cold bath.
• How does nature know how to cool? A natural cold bath can be mimicked with a reservoir of "meter" qubits that are initialized in their ground state.
• We show that a quantum system can be cooled without knowledge of system details when system-meter interactions and meter splittings are chosen randomly.