Stabilizing a Bell state of two superconducting qubits by dissipation engineering

Zaki Leghtas (1, 2) , Uri Vool (1) , Shyam Shankar (1) , Michael Hatridge (1) , Steven M. Girvin (1) , Michel H. Devoret (1) , Mazyar Mirrahimi (1, 2)

1 Yale University [New Haven]
2 SISYPHE - SIgnals and SYstems in PHysiology & Engineering

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 (CHSH correlation larger than 2.6) for arbitrary long times.

Domaines: Physique Quantique [quant-ph]

Zaki Leghtas, Uri Vool, Shyam Shankar, Michael Hatridge, Steven M. Girvin, et al.. Stabilizing a Bell state of two superconducting qubits by dissipation engineering. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2013, 88, pp.023849. ⟨hal-00845158⟩