Bell M T, Zhang W, Ioffe L B, Gershenson M E
Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA.
Department of Electrical Engineering, University of Massachusetts, Boston, Massachusetts 02125, USA.
Phys Rev Lett. 2016 Mar 11;116(10):107002. doi: 10.1103/PhysRevLett.116.107002. Epub 2016 Mar 10.
We observe the effect of the Aharonov-Casher (AC) interference on the spectrum of a superconducting system containing a symmetric Cooper pair box (CPB) and a large inductance. By varying the charge n_{g} induced on the CPB island, we observe oscillations of the device spectrum with the period Δn_{g}=2e. These oscillations are attributed to the charge-controlled AC interference between the fluxon tunneling processes in the CPB Josephson junctions. The measured phase and charge dependences of the frequencies of the |0⟩→|1⟩ and |0⟩→|2⟩ transitions are in good agreement with our numerical simulations. Almost complete suppression of the single fluxon tunneling due to destructive interference is observed for the charge n_{g}=e(2n+1). The CPB in this regime enables fluxon pairing, which can be used for the development of parity-protected superconducting qubits.
我们观察了阿哈罗诺夫 - 卡什尔（AC）干涉对包含对称库珀对盒（CPB）和大电感的超导系统能谱的影响。通过改变CPB岛诱导的电荷(n_{g})，我们观察到器件能谱以周期(\Delta n_{g}=2e)振荡。这些振荡归因于CPB约瑟夫森结中磁通子隧穿过程之间的电荷控制AC干涉。测量的(|0⟩→|1⟩)和(|0⟩→|2⟩)跃迁频率的相位和电荷依赖性与我们的数值模拟结果吻合良好。对于电荷(n_{g}=e(2n + 1))，由于相消干涉观察到单磁通子隧穿几乎完全被抑制。在此 regime 下的CPB实现了磁通子配对，这可用于开发宇称保护的超导量子比特。
