Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
Phys Rev Lett. 2013 Apr 26;110(17):173603. doi: 10.1103/PhysRevLett.110.173603.
We demonstrate quantum control and entanglement generation using a Landau-Zener beam splitter formed by coupling two transmon qubits to a superconducting cavity. Single passage through the cavity-mediated qubit-qubit avoided crossing provides a direct test of the Landau-Zener transition formula. Consecutive sweeps result in Landau-Zener-Stückelberg interference patterns, with a visibility that can be sensitively tuned by adjusting the level velocity through both the nonadiabatic and adiabatic regimes. Two-qubit state tomography indicates that a Bell state can be generated via a single passage, with a fidelity of 78% limited by qubit relaxation.
我们展示了使用 Landau-Zener 分束器进行量子控制和纠缠态生成，该分束器由两个超导量子比特耦合到一个超导腔形成。单通道通过腔介导的量子比特交叉提供了对 Landau-Zener 跃迁公式的直接测试。连续扫描导致 Landau-Zener-Stückelberg 干涉模式，其可见度可以通过调整非绝热和绝热区域的能级速度来敏感地调节。两量子比特态层析成像表明，通过单次通过可以生成贝尔态，保真度为 78%，受限于量子比特弛豫。
