Department of Physics, University of Jyväskylä, PB 35, 40014 Jyväskylä, Finland.
Phys Rev Lett. 2012 Nov 2;109(18):187001. doi: 10.1103/PhysRevLett.109.187001. Epub 2012 Oct 31.
Quantum fluctuations in quasi-one-dimensional superconducting channels leading to spontaneous changes of the phase of the order parameter by 2π, alternatively called quantum phase slips (QPS), manifest themselves as the finite resistance well below the critical temperature of thin superconducting nanowires and the suppression of persistent currents in tiny superconducting nanorings. Here we report the experimental evidence that in a current-biased superconducting nanowire the same QPS process is responsible for the insulating state--the Coulomb blockade. When exposed to rf radiation, the internal Bloch oscillations can be synchronized with the external rf drive leading to formation of quantized current steps on the I-V characteristic. The effects originate from the fundamental quantum duality of a Josephson junction and a superconducting nanowire governed by QPS--the QPS junction.
在准一维超导通道中，量子涨落导致有序参数相位发生 2π 的自发变化，也称为量子相位滑移（QPS），表现为在薄超导纳米线的临界温度以下出现有限电阻，以及微小超导纳米环中持续电流的抑制。在这里，我们报告实验证据表明，在电流偏置的超导纳米线中，相同的 QPS 过程负责绝缘状态——库仑阻塞。当暴露于射频辐射时，内部布洛赫振荡可以与外部射频驱动同步，导致 I-V 特性上形成量化电流阶跃。这些效应源于约瑟夫森结和由 QPS 控制的超导纳米线的基本量子对偶性——QPS 结。
