Research
Telecom spin-photon interfaces in silicon
Optically interfaced solid-state spins are a promising platform for quantum science and technology, providing high-fidelity state initialization and readout, long-lived quantum memory, and spin-photon entanglement generation. Leveraging mature techniques developed in electron spin resonance, quantum optics, and material engineering, our group creates and studies these defect-based electron spin qubits and long-lived nuclear ancilla spins in solid-state materials. Currently our group is particularly interested in telecom interfaced solid-state spin qubits (e.g. T centers and other theory-predicted defects) in silicon. Our primary objective is to identify the optimal defect spins in silicon with desired optical and spin properties for developing novel quantum networking and quantum information processing technologies.
Recommended reading:
Bergeron A. et al. "Silicon-Integrated Telecommunications Photon-Spin Interface" PRX Quantum 1, 020301 (2020)
Higginbottom D. et al. "Optical observation of single spins in silicon" Nature 607, 266 (2022)
Xiong Y. et al. "High-throughput identification of spin-photon interfaces in silicon" Sci. Adv. 9, eadh8617 (2023)
Johnston A. et al. "Cavity-coupled telecom atomic source in silicon" Nat. Commun. 15, 2350 (2024)
Cavity-enhanced network nodesÂ
Our group exploits the low-loss, small mode-volume optical nanocavity to enhance the weak light-matter interactions for atomic-sized defects in solids. We develop novel quantum optical methods to enable coherent control and measurement of these spin qubits and photon-mediated spin interactions for multi-qubit gate operations. On theory side, we aim to devise cavity-enhanced light-matter and matter-matter interaction schemes and elucidate the system dynamics by solving the Lindbladian master equation. Experimentally, we perform quantum spectroscopy and spin measurements for multiple defects in the cavity generated via focused-ion-beam-based ion implantation.Â
Recommended reading:
Reiserer A. et al. "Cavity-based quantum networks with single atoms and optical photons" Rev. Mod. Phys. 87, 1379 (2015)
Nguyen C. et al. "An integrated nanophotonic-vacancy spins in diamond" Phys. Rev. B 100, 165428 (2019)
Chen S. et al. "Parallel single-shot measurement and coherent control of solid-state spins below the diffraction limit" Science 370, 592 (2020)
Johnston A. et al. "Cavity-coupled telecom atomic source in silicon" Nat. Commun. 15, 2350 (2024)
Afzal F. et al. "Distributed Quantum Computing in Silicon" arXiv: 2406.01704 (2024)
Spin-based integrated silicon quantum photonic chips
Exploiting defect spins in silicon enables device integration on the silicon platform, taking advantage from the scalability ensured by the mature silicon technology. Specifically, our group focuses on building spin-based silicon on-chip quantum platforms. Such quantum photonic chips integrate defect spin qubits and quantum memories with photonic circuit components, such as planar out-couplers, low-loss optical cavities, heterogeneously integrated reconfigurable photonic elements (e.g. EOMs), and highly efficient superconducting nanowire single-photon detectors (SNSPDs). Our objective is to develop and distribute these hybrid integrated silicon quantum photonic chips as multiplexed quantum registers and repeaters at distant quantum nodes, for information processing and quantum networking applications.
Recommended reading:
Akhlaghi M. et al. "Waveguide integrated superconducting single-photon detectors implemented as near-perfect absorbers of coherent radiation" Nat. Commun. 6, 8233 (2015)
Eltes F. et al. "An integrated optical modulator operating at cryogenic temperatures" Nat. Mater. 19, 1164 (2020)
Lukin D. et al. "4H-silicon-carbide-on-insulator for integrated quantum and nonlinear photonics" Nat. Photon. 14, 330 (2020)
Pelucchi E. et al. "The potential and global outlook of integrated photonics for quantum technologies" Nat. Rev. Phys. 4, 194 (2022)
Li L. et al. "Heterogeneous integration of spin-photon interfaces with a CMOS platform" Nature 630, 70 (2024)
Hybrid quantum networks
Quantum networks enable a wide range of applications including building a quantum internet for secure quantum communications and distributed quantum computing. Such a scheme represents a fundamental paradigm shift from scaling up individual quantum systems, allowing us to construct larger quantum systems by connecting distributed quantum processing units through remote entanglement. To build large-scale quantum networks, our group will leverage defect spins in silicon to construct multiplexed quantum repeaters, which are capable of generating high-rate indistinguishable telecom photons and high-fidelity spin-photon entanglement, as well as remote spin entanglement. Through collaboration, we will also explore the idea of building hybrid quantum networks where different quantum platforms (e.g., superconducting qubits, trapped ions) are connected to the same network. To bridge the frequency discrepancy for different platforms, microwave-to-optical quantum transduction and nonlinear frequency conversion will be implemented.
Recommended reading:
Bhaskar M. et al. "Experimental demonstration of memory-enhanced quantum communication" Nature 580, 60 (2020)
Leent. T. et al. "Entangling single atoms over 33 km telecom fibre" Nature 607, 69 (2022)
Rochman J. et al. "Microwave-to-optical transduction with erbium ions coupled to planar photonic and superconducting resonators" Nat. Commun. 14, 1153 (2023)
Ourari S. et al. "Indistinguishable telecom band photons from a single Er ion in the solid state" Nature 620, 977 (2023)
Knaut C. et al. "Entanglement of nanophotonic quantum memory nodes in a telecom network" Nature 629, 573 (2024)
Uysal M. et al. "Spin-photon entanglement of a single Er ion in the telecom band" arXiv:2406.06515 (2024)
Krutyanskiy V. et al. "Multimode ion-photon entanglement over 101 kilometers" PRX Quantum 5, 020308 (2024)
Li Y. et al. "High-rate and high-fidelity modular interconnects between neutral atom quantum processors" PRX Quantum 5, 020363 (2024)
