| Description |
MSE PhD Final Defense: Zhancheng Yao
TITLE: Liquid Metal Enabled Modular Architecture of Superconducting Quantum Processor
ADVISOR: David Bishop ECE, Physics, MSE, ME, BME
COMMITTEE: David Abraham IBM Quantum; Oliver Dial IBM Quantum; David Campbell Physics, ECE, MSE; Chair: Karl Ludwig MSE, Physics
ABSTRACT:
Superconducting quantum circuits are promising candidates for realizing fault-tolerant quantum computers. However, unlike classical bits based on transistors, superconducting qubits are susceptible to fabrication defects and aging, necessitating their occasional replacement. A modular architecture with superconducting quantum computing chips can address this issue, wherein individual modules with qubits can be screened, selected, replaced, and then integrated into the larger quantum system. While various modular architectures have been proposed, they are often either permanent or space-inefficient, making the replacement of modules or compact configurations challenging and ultimately limiting the scalability of the system.
Liquid metals (LM), specifically gallium alloys, can be alternatives to solid-state galvanic interconnects. The idea is motivated by their self-healing, self-aligning, and other desirable fluidic properties, potentially enabling the nondestructive replacement of modules at room temperatures, even after operating the entire system at millikelvin regimes. This work demonstrates the first micro-scale LM interconnects bridging two halves of coplanar waveguide resonators (CPWRs), usually used as coupling buses between qubits. The LM-bridged CPWRs exhibit quality factors comparable to conventional solid-state designs, achieving nearly one million in the single-photon, millikelvin regime.
Further, low-loss LM droplets were used to connect separate chiplets, illustrating the feasibility of modular inter-chip connections. Consistent microwave performance over multiple thermal cycles and superconducting resistance before and after module replacement demonstrates the reusability of LM interconnects.
Finally, a preliminary investigation into the underlying physics of the used materials suggests potential directions to improve their quality factors. Together, these results demonstrate the potential of gallium-based liquid metals to enable compact, reconfigurable, and scalable modular quantum computing architectures. |
