碳纳米管超导量子干涉装置

Carbon nanotube superconducting quantum interference device.

作者信息

Cleuziou J-P, Wernsdorfer W, Bouchiat V, Ondarçuhu T, Monthioux M

机构信息

Centre d'Elaboration des Matériaux et d'Etudes Structurales, CEMES-CNRS, 29 rue Jeanne Marvig, 31055 Toulouse Cedex 4, France.

出版信息

Nat Nanotechnol. 2006 Oct;1(1):53-9. doi: 10.1038/nnano.2006.54.

DOI:10.1038/nnano.2006.54

PMID:18654142

Abstract

A superconducting quantum interference device (SQUID) with single-walled carbon nanotube (CNT) Josephson junctions is presented. Quantum confinement in each junction induces a discrete quantum dot (QD) energy level structure, which can be controlled with two lateral electrostatic gates. In addition, a backgate electrode can vary the transparency of the QD barriers, thus permitting change in the hybridization of the QD states with the superconducting contacts. The gates are also used to directly tune the quantum phase interference of the Cooper pairs circulating in the SQUID ring. Optimal modulation of the switching current with magnetic flux is achieved when both QD junctions are in the 'on' or 'off' state. In particular, the SQUID design establishes that these CNT Josephson junctions can be used as gate-controlled pi-junctions; that is, the sign of the current-phase relation across the CNT junctions can be tuned with a gate voltage. The CNT-SQUIDs are sensitive local magnetometers, which are very promising for the study of magnetization reversal of an individual magnetic particle or molecule placed on one of the two CNT Josephson junctions.

摘要

本文介绍了一种具有单壁碳纳米管（CNT）约瑟夫森结的超导量子干涉装置（SQUID）。每个结中的量子限制会诱导出离散的量子点（QD）能级结构，该结构可通过两个横向静电栅极进行控制。此外，背栅电极可以改变量子点势垒的透明度，从而允许量子点态与超导接触之间的杂化发生变化。这些栅极还用于直接调节在SQUID环中循环的库珀对的量子相位干涉。当两个量子点结都处于“开”或“关”状态时，可实现对开关电流与磁通量的最佳调制。特别是，SQUID设计表明这些碳纳米管约瑟夫森结可用作栅极控制的π结；也就是说，通过栅极电压可以调节碳纳米管结两端电流-相位关系的符号。碳纳米管SQUID是灵敏的局部磁力计，对于研究放置在两个碳纳米管约瑟夫森结之一上的单个磁性粒子或分子的磁化反转非常有前景。