Stabilizing a Bell state of two superconducting qubits by dissipation engineering
Zaki Leghtas, Uri Vool, Shyam Shankar, Michael Hatridge, S. M. Girvin, Michel Devoret, Mazyar Mirrahimi · Physical Review A · 2013
We propose a dissipation-engineering scheme that prepares and protects a maximally entangled state of a pair of superconducting qubits. This is done by off-resonantly coupling the two qubits to a low-$Q$ cavity mode playing the role of a dissipative reservoir. We engineer this coupling by applying six continuous-wave microwave drives with appropriate frequencies. The two qubits need not be identical. We show that our approach does not require any fine-tuning of the parameters and requires only that certain ratios between them be large. With currently achievable coherence times, simulations indicate that a Bell state can be maintained over arbitrary long times with fidelities above $94%$. Such performance leads to a significant violation of Bell's inequality (Clauser-Horne-Shimony-Holt correlation larger than 2.6) for arbitrary long times.