Cryogenic, superconducting digital processors offer the promise of greatly reduced operating power for server-class computing systems. This is due to the exceptionally low energy per operation of Single Flux Quantum (SFQ) circuits built from Josephson junction devices operating at the temperature of 4 Kelvin. Possible memory technologies are in the early stages of development. This paper discusses the pros and cons of four alternative memory architectures that could be coupled to SFQ-based processors. The paper concludes that CMOS DRAM operating at 77K can support superconducting processors at low cost-per-bit.
cryogenic, DRAM, Rambus, semiconductor, quantum computing