This study focuses on generating and manipulating squeezed states with two external oscillators coupled by an InP HEMT operating at cryogenic temperatures. First, the small-signal nonlinear model of the transistor at high frequency at 5 K is analyzed using quantum theory, and the related Lagrangian is theoretically derived. Subsequently, the total quantum Hamiltonian of the system is derived using Legendre transformation. The Hamiltonian of the system includes linear and nonlinear terms by which the effects on the time evolution of the states are studied. The main result shows that the squeezed state can be generated owing to the transistor’s nonlinearity; more importantly, it can be manipulated by some specific terms introduced in the nonlinear Hamiltonian. In fact, the nonlinearity of the transistors induces some effects, such as capacitance, inductance, and second-order transconductance, by which the properties of the external oscillators are changed. These changes may lead to squeezing or manipulating the parameters related to squeezing in the oscillators. In addition, it is theoretically derived that the circuit can generate two-mode squeezing. Finally, second-order correlation (photon counting statistics) is studied, and the results demonstrate that the designed circuit exhibits antibunching, where the quadrature operator shows squeezing behavior.

基于70 nm InP HEMT工艺，设计了一款五级共源放大级联结构230~250 GHz低噪声太赫兹单片集成电路（TMIC）。该放大器采用扇形线和微带线构成栅极和源极直流偏置网络，用以隔离射频信号和直流偏置信号；基于噪声匹配技术设计了放大器的第一级和第二级，基于功率匹配技术设计了中间两级，最后一级重点完成输出匹配。在片测试结果表明，230~250 GHz频率范围内，低噪声放大器的小信号增益大于20 dB。采用Y因子法对封装后的低噪声放大器模块完成了噪声测试，频率为243~248 GHz时该MMIC放大器噪声系数优于7.5 dB，与HBT和CMOS工艺相比，基于HEMT工艺的低噪声放大器具有3 dB以上的噪声系数优势。

矢量测量是表征太赫兹波段天线与准光系统波束特性的主流技术。该文介绍了一种基于AlGaN/GaN高电子迁移率晶体管（High-electron-mobility transistor, HEMT）混频探测器的太赫兹矢量测量系统。该系统核心器件为以准光-波导为耦合方式的高灵敏度太赫兹混频探测器，在340 GHz频率外差模式下，其噪声等效功率达−113 dBm/Hz。为了抑制系统相位噪声，搭建了基于二次下变频原理的硬件电路。通过对固定位置天线的长时间测量，表明系统相位稳定度优于4°，系统最小可测功率达到119 nW。基于相干AlGaN/GaN HEMT混频探测器实现了太赫兹连续波幅度和相位分布测量，该工作为后续阵列化太赫兹矢量测量提供了基础。