High fidelity quantum gates and qubit measurements in an all-to-all connected, SNAIL-based quantum module*

As quantum information processors scale to larger size and greater complexity, machines based on networks of qubits coupled only to their nearest-neighbors will suffer from the long times and many operations needed to move information across the qubit fabric. Modular architectures aim to address this by employing dense connectivity within subsets of qubits comprising individual quantum modules, which are ultimately connected together via quantum routers. Here, we present recent work on the design and characterization of a four-qubit module with all-to-all coupling realized by parametric driving of a central SNAIL mode which is compatible with our previously-realized quantum state router [1]. We perform two-qubit gates via three-wave interactions induced by driving the SNAIL at the difference frequency of the qubit modes of interest, enabling iSWAP family gates with gate times shorter than 100 ns. We will present results on improvements made toward achieving 0.99 gate fidelities among all pairs of qubits as well as 0.99 readout fidelity. We will also explore novel gates of interest for more efficient quantum algorithm transpilation, such as B and CNOT gates based on simultaneous parametric drives and explore simple algorithms on this device.