Cryogenic performance evaluation of commercial SP4T microelectromechanical switch for quantum computing applications.

Superconducting quantum computers have emerged as a leading platform for next-generation computing, offering exceptional scalability and unprecedented computational speeds. However, scaling these systems to millions of qubits for practical applications poses substantial challenges, particularly due to interconnect bottlenecks. To address this challenge, extensive research has focused on developing cryogenic multiplexers that enable minimal wiring between room-temperature electronics and quantum processors. This paper investigates the viability of commercial microelectromechanical system (MEMS) switches for cryogenic multiplexers in large-scale quantum computing systems. DC and RF characteristics of the MEMS switches are evaluated at cryogenic temperatures (<10 K) through finite element simulations and experimental measurements. Our results demonstrate that MEMS switches exhibit improved on-resistance, lower operating voltage, and superior RF performance at cryogenic temperatures. In particular, an engineered gate-pulse waveform is introduced to suppress beam bouncing caused by the quasi-vacuum conditions inside the package, enabling stable dynamic operation exceeding 100 million cycles even at cryogenic temperatures. Furthermore, stable single-pole four-throw (SP4T) switching and logical operations, including NAND and NOR gates, are demonstrated at cryogenic temperatures, validating their potential for quantum computing. These results underscore the promise of MEMS switches in realizing large-scale quantum computing systems.