Eichhorn Timon, Jobbitt Nicholas, Bieling Sören, Liu Shuping, Krom Tobias, Serrano Diana, Huber Robert, Lemmer Ulrich, de Riedmatten Hugues, Goldner Philippe, Hunger David
Physikalisches Institut, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany.
Nanophotonics. 2025 Feb 13;14(11):1817-1826. doi: 10.1515/nanoph-2024-0721. eCollection 2025 Jun.
Europium-doped nanocrystals constitute a promising material for a scalable future quantum computing platform. Long-lived nuclear spin states could serve as qubits addressed via coherent optical transitions. In order to realize an efficient spin-photon interface, we couple the emission from a single nanoparticle to a fiber-based microcavity under cryogenic conditions. The spatial and spectral tunability of the cavity permits us to place individual nanoparticles in the cavity, to measure the inhomogeneous linewidth of the ions, and to show a multi-modal Purcell-enhancement of two transition in Eu. A halving of the free-space lifetime to 1.0 ms is observed, corresponding to a 140-fold enhancement of the respective transition. Furthermore, we observe a narrow optical linewidth of 3.3 MHz for a few-ion ensemble in the center of the inhomogeneous line. The results represent an important step towards the efficient readout of single Eu ions, a key requirement for the realization of single-ion-level quantum processing nodes in the solid state.
铕掺杂纳米晶体是构建未来可扩展量子计算平台的一种很有前景的材料。长寿命核自旋态可作为通过相干光学跃迁寻址的量子比特。为了实现高效的自旋 - 光子界面，我们在低温条件下将单个纳米粒子的发射耦合到基于光纤的微腔中。微腔的空间和光谱可调性使我们能够将单个纳米粒子放置在腔内，测量离子的非均匀线宽，并展示铕中两个跃迁的多模态珀塞尔增强。观察到自由空间寿命减半至1.0毫秒，相应跃迁增强了140倍。此外，我们在非均匀线中心的少数离子系综中观察到3.3兆赫兹的窄光学线宽。这些结果是朝着高效读出单个铕离子迈出的重要一步，这是实现固态单离子级量子处理节点的关键要求。
