Abstract
Linking superconducting quantum devices to optical fibers via microwave-optical quantum transducers may enable large-scale quantum networks. For this application, transducers based on the Pockels electro-optic (EO) effect are promising for their direct conversion mechanism, high bandwidth, and potential for low-noise operation. However, previously demonstrated EO transducers require large optical pump power to overcome weak EO coupling and reach high efficiency. Here, we create an EO transducer in thin-film lithium niobate, a platform that provides low optical loss and strong EO coupling. We demonstrate on-chip transduction efficiencies of up to and of optical pump power. The transduction efficiency can be improved by further reducing the microwave resonator’s piezoelectric coupling to acoustic modes, increasing the optical resonator quality factor to previously demonstrated levels, and changing the electrode geometry for enhanced EO coupling. We expect that with further development, EO transducers in thin-film lithium niobate can achieve near-unity efficiency with low optical pump power.
Highlights
Recent advances in superconducting quantum technology [1] have created interest in connecting these devices and systems into larger networks
Here we use a thin-film lithium niobate platform, which combines a large EO coefficient of 32 pm/V, tight confinement of the optical mode to enable a strong EO coupling [47], and the ability to realize low-loss optical resonators with demonstrated quality factors (Q) of 107 [48]
The microwave resonator loss rate can be reduced through improved engineering of the bulk acoustic waves to which the microwave resonator couples and elimination of amorphous cladding materials
Summary
Recent advances in superconducting quantum technology [1] have created interest in connecting these devices and systems into larger networks. The efficiency of EO transducers can be improved by minimizing the loss rates of the resonators and enhancing the EO interaction strength Toward this end, here we use a thin-film lithium niobate platform, which combines a large EO coefficient of 32 pm/V, tight confinement of the optical mode to enable a strong EO coupling [47], and the ability to realize low-loss optical resonators with demonstrated quality factors (Q) of 107 [48]. Here we use a thin-film lithium niobate platform, which combines a large EO coefficient of 32 pm/V, tight confinement of the optical mode to enable a strong EO coupling [47], and the ability to realize low-loss optical resonators with demonstrated quality factors (Q) of 107 [48] These properties make lithium niobate a compelling platform for improving transduction efficiency with EO transducers. Low-loss tunable filters can be integrated on-chip with our device to reduce filtering losses in transduction protocols [51]
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