Quantum linear feedback control with entanglement assistance

The great advantage of quantum metrology relies on the effective use of entanglement, which indeed allows us to achieve strictly better estimation performance over the so-called standard quantum limit. In this paper, we study an analogous strategy utilizing entanglement in a feedback control problem and show that, in the problem of cooling a nano-mechanical oscillator, it indeed can lower the control cost function below the limit attainable by the standard control method.