Integrated Quantum Photonics Lab
Dr. Di Zhu | National University of Singapore
Research
We work on integrated photonic devices for scalable quantum information.
The coming decade will likely witness technology revolutions enabled by quantum science and engineering. Optical photons are ideal quantum information carriers and have led to numerous breakthroughs in quantum communication, networking, sensing, and computation. Despite impressive proof-of-concept demonstrations, implementing practical quantum algorithms requires a new level of complexity, where thousands to millions of optical elements need to be put together. Integrated photonics is likely the only solution.
Our research aims to develop an integrated photonic platform for scalable quantum information, allowing single-photon generation, control, and detection on a single integrated chip. We rely on two key technologies -- thin-film lithium niobate photonics and superconducting nanowire detectors.
Our expertise is in nanofabrication, integrated photonics, and applied superconductivity. Beyond integrated quantum photonics, our research extends broadly to nanoplasmonics, superconducting microwave circuits, and classical optoelectronics devices.
Thin-film lithium niobate (TFLN) integrated photonics
Lithium niobate offers many attractive properties that are critically missing in existing leading integrated photonics platforms, such as large electro-optic and piezoelectric coefficients, strong second-order nonlinearity, and engineerable ferroelectric domains. We utilize these properties to realize key functionalities such as efficient quantum light generation, coherent spectral control, and ultra-fast switching, and coherent microwave-optical transduction.
Selected relevant publications:
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D. Zhu, et al., “Integrated photonics on thin-film lithium niobate,” Advances in Optics and Photonics 13(2), 242-352 (2021)
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D. Zhu*, C. Chen*, M. Yu*, et al., “Spectral control of nonclassical light pulses using an integrated thin-film lithium niobate modulator,” Light: Science & Applications 11, 327 (2022)
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L. Shao*, D. Zhu*, et al., “Electrical control of surface acoustic waves,” Nature Electronics (2022)
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M. Yu, et al., “Integrated femtosecond pulse generator on thin-film lithium niobate,” Nature (2022)
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Y. Hu, et al.“On-chip electro-optic frequency shifters and beam splitters,” Nature 599, 587–593 (2021)
Superconducting nanowire single-photon detectors (SNSPD)
SNSPDs are currently the best-performance single-photon detection technology. We study new device architectures to unlock missing functionalities and enable scalable fabrication and readout. We also explore heterogeneous integration between superconducting devices and photonic circuits to tackle outstanding challenges in quantum computing and quantum networks, such as single-photon feedforward, coherent microwave-optical transduction, and optical control/readout of superconducting devices.
Selected relevant publications
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D. Zhu*, M. Colangelo*, et al. “Resolving photon numbers using a superconducting nanowire with impedance-matching taper,” Nano Letters 20(5) 3858–3863 (2020).
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B. Korzh, et al., “Demonstration of sub-3 ps temporal resolution with a superconducting nanowire single-photon detector,” Nature Photonics 14, 250-255 (2020)
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D. Zhu, et al. “A scalable multi-photon coincidence detector based on superconducting nanowires,” Nature Nanotechnology 3, 596–601 (2018)
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Q.-Y. Zhao, D. Zhu, et al., “Superconducting nanowire single-photon imager,” Nature Photonics 11(4) 247 (2017)