arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 0908.0713cond-mat.mes-hallcond-mat.supr-con
收藏

弹道石墨烯基约瑟夫森结中可能的量子亚稳态分析

Analysis of Possible Quantum Metastable States in Ballistic Graphene-based Josephson Junctions

Joseph G. Lambert, Steven Carabello, Roberto C. Ramos

摘要:

石墨烯是一种相对较新的材料(2004年),由碳原子层排列成蜂窝状晶格。约瑟夫森结器件由石墨烯通过在石墨烯薄片上沉积两个平行的超导引线制成。这些器件具有滞后的电流-电压特性,在微波辐照下出现超导分支和夏皮罗台阶。这些性质促使我们研究量子亚稳态的存在下,发现在传统的电流偏置约瑟夫森结类似。我们目前的工作调查弹道石墨约瑟夫森结的这些亚稳态的性质。我们为这些设备和估计参数,如能级间距和临界电流的有效搓衣板电位建模,以推断观察亚稳态所需的设计。我们提出了一个并行的片上电容器和悬浮石墨烯组成的设备。需要电容器将能级间隔降低到实验可达到的1-20 GHz范围。悬浮的石墨烯有助于降低否则可能来自绝缘氧化物层中的两能级状态的噪声。此外,其临界电流的背栅电压控制为量子控制引入了另一个旋钮。我们还将报告目前的实验进展,在该地区的制造这一拟议的设备。

英文摘要:

Graphene is a relatively new material (2004) made of atomic layers of carbon arranged in a honeycomb lattice. Josephson junction devices are made from graphene by depositing two parallel superconducting leads on a graphene flake. These devices have hysteretic current-voltage characteristics with a supercurrent branch and Shapiro steps appear when irradiated with microwaves. These properties motivate us to investigate the presence of quantum metastable states similar to those found in conventional current-biased Josephson junctions. We present work investigating the nature of these metastable states for ballistic graphene Josephson junctions. We model the effective Washboard potential for these devices and estimate parameters, such as energy level spacing and critical currents, to deduce the design needed to observe metastable states. We propose devices consisting of a parallel on-chip capacitor and suspended graphene. The capacitor is needed to lower the energy level spacing down to the experimentally accessible range of 1-20 GHz. The suspended graphene helps reduce the noise that may otherwise come from two-level states in the insulating oxide layer. Moreover, back-gate voltage control of its critical current introduces another knob for quantum control. We will also report on current experimental progress in the area of fabrication of this proposed device.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑