Colloquium- Chen Wang (Univ. of Massachusetts)- Towards next-generation physical and logical qubits in superconducting circuits

Abstract: Recent advances in quantum information science and engineering have led to universally programmable quantum devices exceeding the computational reach of classical computers.  However, to realize quantum speedup in practical applications, error-corrected logical qubits with many orders of magnitude lower error rates are required. Today’s physical qubits remain too noisy to efficiently scale under the canonical paradigm of fault-tolerant quantum error correction. 

In this talk, I will introduce superconducting circuits not only as a leading quantum technology, but also a unique platform to co-design the physical degrees of freedom and the logical encodings.  The ability of adding complexity on the hardware level to suppress and correct physical errors provides fundamental advantages to innovate towards next-generation of more protected qubits and gates.  We will briefly survey several directions of our research, ranging from understanding physical noise sources in materials to inform coherence improvement, to designing transition matrix element hierarchies for high-fidelity gates, to tailoring environmental dissipation to correct dominant errors. In particular, I will highlight our recent demonstration of autonomous quantum error correction (AQEC) on a Schrodinger cat qubit in a superconducting cavity.