Department of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA.
Phys Rev Lett. 2011 Dec 9;107(24):240501. doi: 10.1103/PhysRevLett.107.240501. Epub 2011 Dec 5.
Superconducting quantum circuits based on Josephson junctions have made rapid progress in demonstrating quantum behavior and scalability. However, the future prospects ultimately depend upon the intrinsic coherence of Josephson junctions, and whether superconducting qubits can be adequately isolated from their environment. We introduce a new architecture for superconducting quantum circuits employing a three-dimensional resonator that suppresses qubit decoherence while maintaining sufficient coupling to the control signal. With the new architecture, we demonstrate that Josephson junction qubits are highly coherent, with T2 ∼ 10 to 20 μs without the use of spin echo, and highly stable, showing no evidence for 1/f critical current noise. These results suggest that the overall quality of Josephson junctions in these qubits will allow error rates of a few 10(-4), approaching the error correction threshold.
基于约瑟夫森结的超导量子电路在展示量子行为和可扩展性方面取得了快速进展。然而，未来的前景最终取决于约瑟夫森结的固有相干性，以及超导量子比特是否能够与其环境充分隔离。我们引入了一种新的超导量子电路架构，采用三维谐振器，在保持与控制信号充分耦合的同时抑制量子比特退相干。使用新架构，我们证明了约瑟夫森结量子比特具有高度相干性，T2∼10 到 20 μs，无需使用自旋回波，并且非常稳定，没有出现 1/f 临界电流噪声的迹象。这些结果表明，这些量子比特中约瑟夫森结的整体质量将允许误差率达到几个 10(-4)，接近纠错阈值。
