IQUIST Special Seminar: Chao Zhou, University of Pittsburg

Precisely controlled couplings between qubits are vital parts of all quantum information processing. For superconducting qubits, most platforms employ a network of two-body interactions between nearest-neighbor qubits in a two-dimensional lattice, the so-called “surface code” structure. However, longer range and multi-node couplings are very desirable as they reduce the overhead of interactions between distant qubits, and enable new topologies for large-scale quantum computers. In my PhD research, I have been working on realizing such qubit connections via parametric interactions and using them to build modular quantum computers.  We have realized two modular machines: a modular quantum state router with all-to-all couplings among 4 modules [1], and a compact 4-qubit quantum module. Both systems are designed with the idea of coupling multiple computational modes to a central Superconducting Nonlinear Asymmetric Inductive eLement (SNAIL) and are fully controlled with 3-wave-mixing parametric interactions. I will present experiment results measured in both systems, including fast all-to-all gates between arbitrary module cavity pairs, high-fidelity single and multi-qubit parametric gates, and inter/intra-module qubit entanglement. The operations demonstrated here can readily be extended to faster and higher-fidelity parametric operations, as well as scaled to support larger networks of modular quantum computers [2].

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