Information transfer between a microwave field and light, also known as microwave-to optical transduction, is a key area of research in quantum communication technology aimed at developing an interface between the superconducting processing devices operating at microwave frequencies and optical photons used for transferring quantum information over distance. Atomic vapors offer a good platform for such interfaces since they naturally support transitions at microwave and optical frequencies. In this work, we explored microwave-to-optical transduction in rubidium ensembles. We proposed a transduction method based on microwave-optical double resonance, where we can control the ensemble optical properties via non-linear interactions with a microwave magnetic field. With this method, we demonstrate the transduction of an audio signal from frequency-modulated and amplitude-modulated microwave fields to optical intensity modulation. We also present a protocol for engineering atomic spin polarization with microwave-assisted optical pumping and consider its applications for polarization-selective frequency conversion and microwave-controlled optical rotation.Information transfer between a microwave field and light, also known as microwave-to optical transduction, is a key area of research in quantum communication technology aimed at developing an interface between the superconducting processing devices operating at microwave frequencies and optical photons used for transferring quantum information over distance. Atomic vapors offer a good platform for such interfaces since they naturally support transitions at microwave and optical frequencies. In this work, we explored microwave-to-optical transduction in rubidium ensembles. We proposed a transduction method based on microwave-optical double resonance, where we can control the ensemble optical properties via non-linear interactions with a microwave magnetic field. With this method, we demonstrate the transduction of an audio signal from frequency-modulated and amplitude-modulated microwave fields to optical intensity modulation. We also present a protocol for engineering atomic spin polarization with microwave-assisted optical pumping and consider its applications for polarization-selective frequency conversion and microwave-controlled optical rotation.

Jan 1, 20210 citations

Microwave Quantum Photonics

Bixuan Fan, Gerard J Milburn, Thomas M. Stace

Quantum science and technologyJan 1, 20161 citation

A frequency-agile microwave-optical interface for superconducting qubits

Yufeng Wu, Yiyu Zhou, Haoqi Zhao +4 more

Superconducting quantum processors operate at microwave frequencies in millikelvin environments, making it challenging to interconnect distant nodes using conventional microwave wiring. Coherent microwave-to-optical (M2O) transduction enables superconducting quantum networks by interfacing itinerant microwave photons with low-loss optical fiber. However, many state-of-the-art transducers provide efficient conversion only over a narrow frequency span, complicating deployment with heterogeneous superconducting devices that are detuned by gigahertz-scale offsets. Here we demonstrate a frequency-agile microwave-optical interface that overcomes this bandwidth mismatch by cascading an electro-optic M2O transducer with a multimode microwave-to-microwave (M2M) frequency converter, with in situ tunability of the microwave resonances in both stages. Using this architecture, we realize continuous frequency coverage from 5.0 to 8.5 GHz within a single system. As an application relevant to superconducting-qubit networking, we use the cascaded M2M-M2O interface to optically read out a superconducting qubit whose readout resonator is detuned by 1.7 GHz from the native M2O microwave resonance, demonstrating a scalable route toward fiber-linked superconducting quantum nodes.Superconducting quantum processors operate at microwave frequencies in millikelvin environments, making it challenging to interconnect distant nodes using conventional microwave wiring. Coherent microwave-to-optical (M2O) transduction enables superconducting quantum networks by interfacing itinerant microwave photons with low-loss optical fiber. However, many state-of-the-art transducers provide efficient conversion only over a narrow frequency span, complicating deployment with heterogeneous superconducting devices that are detuned by gigahertz-scale offsets. Here we demonstrate a frequency-agile microwave-optical interface that overcomes this bandwidth mismatch by cascading an electro-optic M2O transducer with a multimode microwave-to-microwave (M2M) frequency converter, with in situ tunability of the microwave resonances in both stages. Using this architecture, we realize continuous frequency coverage from 5.0 to 8.5 GHz within a single system. As an application relevant to superconducting-qubit networking, we use the cascaded M2M-M2O interface to optically read out a superconducting qubit whose readout resonator is detuned by 1.7 GHz from the native M2O microwave resonance, demonstrating a scalable route toward fiber-linked superconducting quantum nodes.

quant-pharXiv:2602.24098Mar 2, 20260 citations

Efficient quantum microwave-to-optical conversion using electro-optic nanophotonic coupled resonators

Mohammad Soltani, Mian Zhang, Colm A. Ryan +3 more

We propose a low-noise, triply resonant, electro-optic (EO) scheme for quantum microwave-to-optical conversion based on coupled nanophotonics resonators integrated with a superconducting qubit. Our optical system features a split resonance---a doublet---with a tunable frequency splitting that matches the microwave resonance frequency of the superconducting qubit. This is in contrast to conventional approaches, where large optical resonators with free-spectral range comparable to the qubit microwave frequency are used. In our system, EO mixing between the optical pump coupled into the low-frequency doublet mode and a resonance microwave photon results in an up-converted optical photon on resonance with high-frequency doublet mode. Importantly, the down-conversion process, which is the source of noise, is suppressed in our scheme as the coupled-resonator system does not support modes at that frequency. Our device has at least an order of magnitude smaller footprint than conventional devices, resulting in large overlap between optical and microwave fields and a large photon conversion rate ($g/2\ensuremath{\pi}$) in the range of $\ensuremath{\sim}5$--15 kHz. Owing to a large $g$ factor and doubly resonant nature of our device, microwave-to-optical frequency conversion can be achieved with optical pump powers in the range of tens of microwatts, even with moderate values for optical $\mathit{Q}$ ($\ensuremath{\sim}{10}^{6}$) and microwave $Q$ ($\ensuremath{\sim}{10}^{4}$). The performance metrics of our device, with substantial improvement over the previous EO-based approaches, promise a scalable quantum microwave-to-optical conversion and networking of superconducting processors via optical fiber communication.We propose a low-noise, triply resonant, electro-optic (EO) scheme for quantum microwave-to-optical conversion based on coupled nanophotonics resonators integrated with a superconducting qubit. Our optical system features a split resonance---a doublet---with a tunable frequency splitting that matches the microwave resonance frequency of the superconducting qubit. This is in contrast to conventional approaches, where large optical resonators with free-spectral range comparable to the qubit microwave frequency are used. In our system, EO mixing between the optical pump coupled into the low-frequency doublet mode and a resonance microwave photon results in an up-converted optical photon on resonance with high-frequency doublet mode. Importantly, the down-conversion process, which is the source of noise, is suppressed in our scheme as the coupled-resonator system does not support modes at that frequency. Our device has at least an order of magnitude smaller footprint than conventional devices, resulting in large overlap between optical and microwave fields and a large photon conversion rate ($g/2\ensuremath{\pi}$) in the range of $\ensuremath{\sim}5$--15 kHz. Owing to a large $g$ factor and doubly resonant nature of our device, microwave-to-optical frequency conversion can be achieved with optical pump powers in the range of tens of microwatts, even with moderate values for optical $\mathit{Q}$ ($\ensuremath{\sim}{10}^{6}$) and microwave $Q$ ($\ensuremath{\sim}{10}^{4}$). The performance metrics of our device, with substantial improvement over the previous EO-based approaches, promise a scalable quantum microwave-to-optical conversion and networking of superconducting processors via optical fiber communication.

arXiv:1711.00346Physical Review AOct 5, 201779 citations

Quantum Communication with Microwave Photons

Andreas J. Wallraff

Bulletin of the American Physical SocietyMar 4, 20190 citations

Building a quantum interface between microwave and optical photons

A. Vainsencher, G. A. Peairs, Kevin J. Satzinger +1 more

Bulletin of the American Physical SocietyMar 5, 20150 citations

g

factor and doubly resonant nature of our device, microwave-to-optical frequency conversion can be achieved with optical pump powers in the range of tens of microwatts, even with moderate values for optical

\mathit{Q}

($\ensuremath{\sim}{10}^{6}$) and microwave

Q

($\ensuremath{\sim}{10}^{4}$). The performance metrics of our device, with substantial improvement over the previous EO-based approaches, promise a scalable quantum microwave-to-optical conversion and networking of superconducting processors via optical fiber communication.