Ultralong lifetimes of silicon nanomechanical resonators at cryogenic temperatures and microwave frequencies make them promising resources in quantum engineering. In this work, we propose a nanomechanical qubit achieving strong single-phonon level anharmonicity of 5 MHz without the need for coupling to an ancillary qubit of a hybrid quantum architecture. This qubit design combines a nano-machined silicon cantilever brought in proximity to a silicon surface using microelectromechanical actuators. The surface forces between the cantilever and the silicon surface provide an effective nonlinear potential, allowing for the realization of the nanomechanical qubit. We optimize the structure to achieve low thermal noise, large anharmonicity, and efficient dispersive readout via mechanical coupling to another nanomechanical resonator. We further employ finite element modeling to calculate the cavity quantum acoustodynamics parameters for single- and two-qubit control and dispersive readout with microwaves. The potential of combining strong single phonon anharmonicity of ~ 5 MHz, ultrahigh mechanical quality factors (~10^10), small footprint, and ease of manufacturing make this platform promising for quantum information processing.
Project is currently funded by: Federal