Flux qubits fabricated using a high-coherence transmon process

Over the past years, superconducting circuit qubit lifetimes have been continuing to increase, largely due to design enhancements in addition to processing and fabrication evolution. While the earliest designs of Cooper pair boxes exhibited T₁ coherence times on the order of 1 ns, there are recent reports of transmon lifetimes exceeding 100 μs. We now apply these advances in processing to look back upon flux qubits, and we present an 8-qubit ring of alternating flux qubits and tunable transmons, with coupling between nearest neighbors. Preliminary work focuses on optimizing flux qubit design and increasing experimentally observed coherence times, with motivation from theoretical studies and numerical simulations targeting energy structure and noise coupling. Meanwhile, further theoretical investigations into novel two qubit gate designs between flux qubits and transmons, which leverage their opposing anharmonicities, are underway.