Two-level system hyperpolarization using a quantum Szilard engine

The innate complexity of solid state physics exposes superconducting quantum circuits to interactions with uncontrolled degrees freedom degrading their coherence. By using a simple stabilization sequence we show that fluxonium qubit is coupled two-level system (TLS) environment unknown origin, relatively long energy relaxation time exceeding $50\,\text{ms}$. Implementing Szilard engine an active feedback control loop allows us decide whether the heats or cools its TLS environment. TLSs can be cooled down resulting in four times lower population, they heated manifest themselves as negative temperature corresponding population $\sim 80\,\%$. We and are each other's dominant loss mechanism independent populations. Understanding mitigating environments therefore not only crucial improve lifetimes but also avoid non-Markovian dynamics.