IBM Watson Research Center, Yorktown Heights, NY 10598, USA.
J Phys Condens Matter. 2010 Feb 10;22(5):053201. doi: 10.1088/0953-8984/22/5/053201. Epub 2010 Jan 15.
We present details and results for a superconducting quantum bit (qubit) design in which a tunable flux qubit is coupled strongly to a transmission line. Quantum information storage in the transmission line is demonstrated with a dephasing time of T(2)∼ 2.5 µs. However, energy lifetimes of the qubit are found to be short (∼ 10 ns) and not consistent with predictions. Several design and material changes do not affect qubit coherence times. In order to determine the cause of these short coherence times, we fabricated standard flux qubits based on a design which was previously successfully used by others. Initial results show significantly improved coherence times, possibly implicating losses associated with the large size of our qubit.
我们介绍了一种超导量子比特（qubit）设计的细节和结果，其中可调谐磁通量子比特与传输线强耦合。通过相位弛豫时间 T(2)∼ 2.5 μs 证明了传输线中的量子信息存储。然而，发现量子比特的能量寿命很短（∼ 10 ns），并且与预测不一致。几种设计和材料变化并不影响量子比特的相干时间。为了确定这些短相干时间的原因，我们根据以前其他人成功使用的设计制造了标准磁通量子比特。初步结果显示相干时间有了显著提高，这可能表明与我们的量子比特尺寸较大相关的损耗。
