Cedergren Karin, Ackroyd Roger, Kafanov Sergey, Vogt Nicolas, Shnirman Alexander, Duty Timothy
Centre for Engineered Quantum Systems (EQuS), School of Physics, University of New South Wales, Sydney 2052, Australia.
Chemical and Quantum Physics, School of Science, RMIT University, Melbourne 3001, VIC 3001 Australia.
Phys Rev Lett. 2017 Oct 20;119(16):167701. doi: 10.1103/PhysRevLett.119.167701. Epub 2017 Oct 18.
Quantum physics in one spatial dimension is remarkably rich, yet even with strong interactions and disorder, surprisingly tractable. This is due to the fact that the low-energy physics of nearly all one-dimensional systems can be cast in terms of the Luttinger liquid, a key concept that parallels that of the Fermi liquid in higher dimensions. Although there have been many theoretical proposals to use linear chains and ladders of Josephson junctions to create novel quantum phases and devices, only modest progress has been made experimentally. One major roadblock has been understanding the role of disorder in such systems. We present experimental results that establish the insulating state of linear chains of submicron Josephson junctions as Luttinger liquids pinned by random offset charges, providing a one-dimensional implementation of the Bose glass, strongly validating the quantum many-body theory of one-dimensional disordered systems. The ubiquity of such an electronic glass in Josephson-junction chains has important implications for their proposed use as a fundamental current standard, which is based on synchronization of coherent tunneling of flux quanta (quantum phase slips).
一维空间中的量子物理极为丰富，然而即便存在强相互作用和无序性，却出人意料地易于处理。这是因为几乎所有一维系统的低能物理都可以用卢廷格液体来描述，这一关键概念类似于高维中的费米液体。尽管有许多理论提议利用约瑟夫森结的线性链和梯子来创造新颖的量子相和器件，但实验上仅取得了有限的进展。一个主要障碍在于理解无序在这类系统中的作用。我们展示的实验结果表明，亚微米约瑟夫森结线性链的绝缘态是由随机偏移电荷钉扎的卢廷格液体，实现了玻色玻璃的一维情形，有力地验证了一维无序系统的量子多体理论。这种电子玻璃在约瑟夫森结链中的普遍存在对其作为基于磁通量子（量子相位滑移）相干隧穿同步的基本电流标准的潜在应用具有重要意义。
