Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China.
Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
Phys Rev Lett. 2016 Feb 26;116(8):086801. doi: 10.1103/PhysRevLett.116.086801. Epub 2016 Feb 25.
We experimentally demonstrate a tunable hybrid qubit in a five-electron GaAs double quantum dot. The qubit is encoded in the (1,4) charge regime of the double dot and can be manipulated completely electrically. More importantly, dot anharmonicity leads to quasiparallel energy levels and a new anticrossing, which help preserve quantum coherence of the qubit and yield a useful working point. We have performed Larmor precession and Ramsey fringe experiments near the new working point and find that the qubit decoherence time is significantly improved over a charge qubit. This work shows a new way to encode a semiconductor qubit that is controllable and coherent.
我们实验演示了一种在五电子 GaAs 双量子点中可调谐的混合量子比特。该量子比特编码在双点的（1,4）电荷态中，可以完全通过电学手段进行操作。更重要的是，点非谐性导致准平行能级和新的交叉，这有助于保持量子比特的相干性，并产生有用的工作点。我们在新的工作点附近进行了拉莫尔进动和 Ramsey 条纹实验，发现与电荷量子比特相比，该量子比特的退相干时间有显著提高。这项工作展示了一种新的半导体量子比特编码方法，它是可控和相干的。
