Demonstrating a high-fidelity bosonic control architecture with a dynamic dispersive shift (part 1 of 2)

Encoding quantum information in bosonic modes provides a promising route toward fault-tolerant quantum computing within circuit-QED architectures. Traditionally, control over these harmonic oscillators is achieved through a direct coupling to auxiliary nonlinear elements, which can, however, introduce unwanted oscillator nonlinearity and dephasing. In this pair of talks, we experimentally demonstrate a multi-oscillator architecture that interrupts the always-on oscillator-transmon connection with a LINC[1] coupler that exhibits near-zero static nonlinearity. Using parametric drives, the LINC mediates resonant exchange interactions, including both oscillator–oscillator and oscillator–transmon couplings, at will. Further, by turning on a detuned exchange interaction, we can dynamically hybridize the oscillator with the nonlinearity, activating a parametric dispersive interaction for bosonic control. With its unique combination of static isolation and high-fidelity parametric operations, this architecture provides a versatile platform for exploring bosonic error correction that is no longer limited by auxiliary elements.

In part 1, we introduce the architecture, demonstrate parametric coupling between modes of interest, and show dynamic dispersive interactions with an on-off ratio of over four orders of magnitude.

[1] A. Maiti et al. "A linear quantum coupler for clean bosonic control" Arxiv:2501.18025