Abstract Low-loss fiber optic links have the potential to connect superconducting quantum processors together over long distances to form large scale quantum networks. A key component of these future networks is a quantum transducer that coherently and bidirectionally converts photons from microwave frequencies to optical frequencies. We present a platform for electro-optic photon conversion based on silicon‐organic hybrid photonics. Our device combines high quality factor microwave and optical resonators with an electro-optic polymer cladding to perform microwave-to-optical photon conversion from 6.7 GHz to 193 THz (1558 nm). The device achieves an electro-optic coupling rate of 590 Hz in a millikelvin dilution refrigerator environment. We use an optical heterodyne measurement technique to demonstrate the single-sideband nature of the conversion with a selectivity of approximately 10 dB. We analyze the effects of stray light in our device and suggest ways in which this can be mitigated. Finally, we present initial results on high-impedance spiral resonators designed to increase the electro-optic coupling.
Converting signals from the microwave to the optical domain has attracted great attention due to its potential applications in the field of quantum networks. Achieving efficient transduction is a significant yet challenging task, where a high efficiency at single photon level and low added noise are required. Electro-opto-mechanics have been proven to be efficient to convert microwave and optical photons bidirectionally. In this work, we propose and demonstrate an enhanced microwave-optical conversion in an electro-opto-mechanical system by introducing a mechanical ancilla attached the microwave resonator. Based on the ancillary electromechanical coupling, the damping rate of the microwave resonator is controlled and further leads to significant enhancement in conversion, such as the increase of conversion efficiency, broadening of conversion bandwidth and reduction of added noise. It provides a feasible approach to realize a broadband microwave-optical conversion with high efficiency. Moreover, the reduced added noise may break the limitation of quantum transduction due to the ancillary electromechanical coupling. Our scheme is also applicable and feasible for opto-mechanics and other systems to achieve practical quantum interface.
An optical network of superconducting quantum bits (qubits) is an appealing platform for quantum communication and distributed quantum computing, but developing a quantum-compatible link between the microwave and optical domains remains an outstanding challenge. Operating at
T<100~mK temperatures, as required for quantum electrical circuits, we demonstrate a mechanically-mediated microwave-optical converter with 47
% conversion efficiency, and use a feedforward protocol to reduce added noise to 38~photons. The feedforward protocol harnesses our discovery that noise emitted from the two converter output ports is strongly correlated because both outputs record thermal motion of the same mechanical mode. We also discuss a quantum feedforward protocol that, given high system efficiencies, allows quantum information to be transferred even when thermal phonons enter the mechanical element faster than the electro-optic conversion rate.