An integrated microwave-to-optics interface for scalable quantum computing, part 2

Two major challenges in the development of practical quantum computers are scalability and linking via networks. Both of these challenges can be addressed by developing a microwave-to-optics quantum transducer. In order for the quantum transducer to effectively create entanglement links between different qubit processing units, several criteria must be fulfilled: the transducer must operate at high efficiency and add less than a single quantum of input referred noise. Furthermore, the transducer should have a large bandwidth and operate at a high repetition rate.

We present here how these criteria can be met by an integrated transducer design. The design uses a mechanical oscillator made of lithium niobate on silicon to transduce photons between a silicon photonic cavity and a planar microwave cavity. We experimentally demonstrate its unique performance through pulsed transduction, for which the added noise is limited to a few photons. Further, we show how the transducer can operate at a repetition rate up to 100 kHz - which together with a bandwidth of 14.8 MHz is paving the way for distributed quantum computing.