Optical Interface for Superconducting Digital Circuits using Low temperature Photon Detectors

使用低温光子探测器的超导数字电路的光学接口

• 批准号: 17360154
• 负责人: MYOREN Hiroaki
• 金额: $ 10.39万
• 依托单位: Saitama University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360154/
• 关键词: Low Temperature Photon Detectors; meander lines; Photo Switches; SFQ Pulse Generation Circuits; Sinele Flux Quantum Logic Circuits; Optical Interface; 単一磁束量子回路; 超伝導フォトン検出器; レーザ光源; 準粒子; Al超伝導電極; ポリイミド; 電子ビーム; 単一磁束量子; 2分岐スイッチ

We investigated superconducting NbN nanowire as a photo switch for generating single flux quantum (SFQ) pulses.Epitaxially grown NbN thin films were prepared on MgO (100) substrates by a dc magnetron sputtering method using gas mixture of Ar + N_2, without substrate heating. NbN thin films showed Tc of 14K for 8 nm, and 10K for 4 nm.NbN nanowires were patterned using a electron direct drawing method with 200 nm thick electron resist. To increasing photo-sensitive regions, we fabricated 50 x 50 μm^2 meander patterns with NbN nanowires. Line width of nanowires was varied from 200 nm to 500 nm. Critical current density of NbN nanowires was about 3x10^6A/cm^2 at 4.2 K.We irradiated 850-nm laser pulses via 50-mm multi-mode optical fibers. Repetition frequency and pulse width could be controlled by a pulse pattern generator. The maximum laser pulse power was about 1 mW. Using 200-nm-wide NbN nanowires, one third of critical current was suppressed by 1 mW CW laser irradiations. High speed responses were observed for laser pulses with repetition frequency of 1MHz and pulse width of 2 ns.On the other hand, we designed an SFQ generation circuit using Josephson transmission lines assuming NbN nanowire switch generates 60 μA current pulses. The designed circuit could generate SFQ pulses by 10 μA, 25 GHz current pulses. Dc bias margin of the circuit was +- 15% for 60 μA current pulses.

研究了NbN纳米线作为光开关产生单通量量子（SFQ）脉冲的方法，在MgO（100）基片上用直流磁控溅射方法，在不加热基片的情况下，用Ar + N2混合气体外延生长NbN薄膜。NbN薄膜的Tc为14 K，为8 nm，和10 K为4 nm。NbN纳米线的图案使用电子直接拉伸方法与200 nm厚的电子抗蚀剂。为了增加光敏区域，我们用NbN纳米线制作了50 × 50 μm^2的曲折图案。纳米线的线宽从200 nm变化到500 nm。NbN纳米线的临界电流密度在4.2 K时约为3 × 10^6A/cm^2。我们通过50 mm多模光纤照射850 nm激光脉冲。重复频率和脉冲宽度可以由脉冲模式发生器控制。最大激光脉冲功率约为1 mW。使用200 nm宽的NbN纳米线，三分之一的临界电流被抑制由1 mW CW激光照射。在重复频率为1 MHz，脉宽为2ns的激光脉冲下，观察到了高速响应。另一方面，假设NbN纳米线开关产生60 μA的电流脉冲，我们设计了一个基于约瑟夫森传输线的SFQ产生电路。所设计的电路可以用10 μA、25 GHz的电流脉冲产生SFQ脉冲。对于60 μA的电流脉冲，电路的直流偏置裕度为± 15%。

项目成果

Minimization of Parastic Inductances in SFQ Circuits using Over-and Under-Ground Planes

使用地上和地下平面最小化 SFQ 电路中的寄生电感

• 发表时间: 2006
• 作者: Myoren H.;Kishita N.;Taino T.;Takada S
• 通讯作者: Takada S

Minimization of Parasitic Inductances in SFQ Circuits Using Over-and Under-Ground Planes

使用地上和地下平面最小化 SFQ 电路中的寄生电感

• 发表时间: 2007
• 期刊: IEEE Trans. Appl. Superconductivity 17
• 作者: Myoren H.;Kishita N.;Taino T.;and Takada S.
• 通讯作者: and Takada S.

Minimization of Parasitic Inductances in SFQ Circuits Using Over- and Under-Ground Planes

使用地上和地下平面最小化 SFQ 电路中的寄生电感

• 发表时间: 2007
• 期刊: IEEE Trans. Appl. Supercond. Vol. 17, No. 2
• 作者: Myoren H.;Kishita N.;Taino T.;and Takada S.
• 通讯作者: and Takada S.

Superconducting NbN Nanowire Photo Switchesf for Generating Single Flux Quantum Pulses

用于生成单通量量子脉冲的超导 NbN 纳米线光电开关

• 发表时间: 2007
• 作者: M.Fukuma;C.Laurent;K.Fukunaga;Hiroaki Myoren
• 通讯作者: Hiroaki Myoren

光インターフェース用SFQ発生回路の設計

光接口SFQ生成电路设计

• 发表时间: 2007
• 作者: 松井 雄二;田井 野徹;明連 広昭;高 田進
• 通讯作者: 高 田進