Long-lived Super-conducting Quantum Circuits Toward Fault-Tolerant Quantum Computing

Dr. Shingo Kono
Postdoctoral Researcher EPFL
Ecole Polytechnique  Federal de Lausanne)

Superconducting quantum circuits represent fully engineerable quantum systems, positioning them as a leading platform for large-scale quantum computing. Nevertheless, scaling up to millions of qubits for fault-tolerant operations remains a significant challenge. Our research focuses on enhancing the quantum lifetimes to significantly reduce the resource requirements. First, we demonstrate state-of-the-art superconducting qubits with relaxation times exceeding 0.5 milliseconds. By leveraging these long-lived qubits as quantum sensors, we discover a completely new qubit loss mechanism attributed to mechanical shocks from a dilution refrigerator, suggesting future error mitigation strategies by isolating superconducting qubits from mechanical environments. Second, we demonstrate long-lived mechanical oscillators based on circuit optomechanics, realized by a novel nanofabrication process involving silicon-etched trenches. This breakthrough enables ultra-coherent and highly scalable mechanical systems, which are useful for quantum memory in superconducting quantum computing.