Quantum Information Processing Using Multimode Circuit-QED

Abstract

Superconducting circuits have emerged as one of the most promising platforms for quantum computation as a result of rapid advances in coherence and control over the past few decades. Most modern superconducting processors are based on the transmon circuit, and rely on nearest-neighbor interactions for gate operations and entanglement. In this talk, I will present an alternative architecture for superconducting quantum information and simulation, involving many harmonic modes of a multimode cavity coupled and controlled by a single quantum circuit. This multimode circuit-QED system leverages the long coherence times and restricted decoherence channels of superconducting microwave cavities. Additionally, the architecture has a high degree of connectivity while being hardware efficient, with gate operations performed between arbitrary pairs of cavity modes using only a few control lines that drive the transmon. Our implementation of such a processor uses - the quantum flute, a novel rectangular 3D multimode cavity with a tailored mode dispersion, that is protected from seam loss and possesses O(10) distinct modes with photon lifetimes approaching a millisecond. I will present various schemes for universal control of the multimode Hilbert space using the dispersively coupled transmon, and discuss schemes for engineering designer photon-photon interactions.