Cryogenic systems operating from room temperature to low Kelvin temperatures are a natural path for stationary computing systems such as data centers for cloud computing and quantum computers. These cryogenic hybrid systems will require a mix of different technologies and functions operating at different temperatures. Superconductive electronics can provide extremely high-speed operation while consuming two to three orders of magnitude less power than semiconductor devices. The most common form of superconductive logic is single flux quantum (SFQ). Complementary metal-oxide semiconductor (CMOS) devices provide massive complexity and cryogenic operation with enhanced device characteristics. However, CMOS dissipates considerable power and operates much slower than SFQ. Hybrid systems integration of SFQ with CMOS can overcome unique challenges when operating at cryogenic temperatures, significantly improving the performance while lowering the energy. Large scale stationary computing infrastructures such as cloud computing desperately needs significantly improved power efficiency while quantum computers can use SFQ to communicate with the interface and control circuitry. The involvement of students from underrepresented populations will be actively pursued at both the undergraduate and graduate levels. Design projects will be developed for advanced undergraduate students to link the learning process of undergraduate courses with active research projects by providing opportunities for these students to gain practical design experience in cryogenic electronics. Both investigators will continue promoting the participation of diverse middle and high school students in engineering and the sciences.<br/> <br/>This project will identify, characterize, and explore hybrid systems integration of cryogenic electronics crossing multiple temperature boundaries. The primary objective is to determine how best to place which function at what temperature with which technology and application in cryogenic hybrid systems. We will develop general purpose guidelines and design methodologies to support the development of complete systems composed of diverse technologies and applications operating across multiple temperature zones to satisfy extreme energy and performance objectives for specific applications.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.