Nonlinear bosonic Maxwell’s demon by coupling to qubits

Abstract The concept of Maxwell’s demon, proposed in classical physics as a means to extract work from a thermodynamics system beyond the constraints set by the second law of thermodynamics, has since been extended to modern quantum physics. Realization of the quantum Maxwell’s demon remains of actual interest given the potential of continuous-variable systems in quantum thermodynamics and current experimental opportunities. We propose a quantum Maxwell’s demon method, based on a Jaynes-Cummings two-level system, for subtracting bosonic energy inferred from successful measurements of excited qubits after linear and nonlinear interactions. The effect of these subtractions can suppress the tails of bosonic noise better than the linear interactions alone. The system statistics reaches an out-of-equilibrium state, becoming much closer to Poissonian distributions as indicated by the mean-to-noise ratio. The inclusion of a few additional optimal nonlinear subtractions can improve the success rate to ten times higher than the linear scheme, making the method significantly more efficient in exciting hundreds of qubits.