More Like this

1. A scalable cavity-based spin–photon interface in a photonic integrated circuit

   https://doi.org/10.1364/OPTICAQ.509233  

   Chen, Kevin_C; Christen, Ian; Raniwala, Hamza; Colangelo, Marco; De_Santis, Lorenzo; Shtyrkova, Katia; Starling, David; Murphy, Ryan; Li, Linsen; Berggren, Karl; et al (April 2024, Optica Quantum)

   A central challenge in quantum networking is transferring quantum states between different physical modalities, such as between flying photonic qubits and stationary quantum memories. One implementation entails using spin–photon interfaces that combine solid-state spin qubits, such as color centers in diamond, with photonic nanostructures. However, while high-fidelity spin–photon interactions have been demonstrated on isolated devices, building practical quantum repeaters requires scaling to large numbers of interfaces yet to be realized. Here, we demonstrate integration of nanophotonic cavities containing tin-vacancy (SnV) centers in a photonic integrated circuit (PIC). Out of a six-channel quantum microchiplet (QMC), we find four coupled SnV-cavity devices with an average Purcell factor of ∼7. Based on system analyses and numerical simulations, we find with near-term improvements this multiplexed architecture can enable high-fidelity quantum state transfer, paving the way toward building large-scale quantum repeaters. 

   more » « less
2. Microwave-Based Quantum Control and Coherence Protection of Tin-Vacancy Spin Qubits in a Strain-Tuned Diamond-Membrane Heterostructure

   https://doi.org/10.1103/PhysRevX.13.041037  

   Guo, Xinghan; Stramma, Alexander M.; Li, Zixi; Roth, William G.; Huang, Benchen; Jin, Yu; Parker, Ryan A.; Arjona Martínez, Jesús; Shofer, Noah; Michaels, Cathryn P.; et al (November 2023, Physical Review X)

   Robust spin-photon interfaces in solids are essential components in quantum networking and sensing technologies. Ideally, these interfaces combine a long-lived spin memory, coherent optical transitions, fast and high-fidelity spin manipulation, and straightforward device integration and scaling. The tin-vacancy center (SnV) in diamond is a promising spin-photon interface with desirable optical and spin properties at 1.7 K. However, the SnV spin lacks efficient microwave control, and its spin coherence degrades with higher temperature. In this work, we introduce a new platform that overcomes these challenges—SnV centers in uniformly strained thin diamond membranes. The controlled generation of crystal strain introduces orbital mixing that allows microwave control of the spin state with 99.36(9)% gate fidelity and spin coherence protection beyond a millisecond. Moreover, the presence of crystal strain suppresses temperature-dependent dephasing processes, leading to a considerable improvement of the coherence time up to 223(10) μs at 4 K, a widely accessible temperature in common cryogenic systems. Critically, the coherence of optical transitions is unaffected by the elevated temperature, exhibiting nearly lifetime-limited optical linewidths. Combined with the compatibility of diamond membranes with device integration, the demonstrated platform is an ideal spin-photon interface for future quantum technologies. 

   more » « less
3. Fabrication of single color centers in sub-50 nm nanodiamonds using ion implantation

   https://doi.org/10.1515/nanoph-2022-0678  

   Xu, Xiaohui; Martin, Zachariah O.; Titze, Michael; Wang, Yongqiang; Sychev, Demid; Henshaw, Jacob; Lagutchev, Alexei S.; Htoon, Han; Bielejec, Edward S.; Bogdanov, Simeon I.; et al (January 2023, Nanophotonics)

   Abstract Diamond color centers have been widely studied in the field of quantum optics. The negatively charged silicon vacancy (SiV − ) center exhibits a narrow emission linewidth at the wavelength of 738 nm, a high Debye–Waller factor, and unique spin properties, making it a promising emitter for quantum information technologies, biological imaging, and sensing. In particular, nanodiamond (ND)-based SiV − centers can be heterogeneously integrated with plasmonic and photonic nanostructures and serve as in vivo biomarkers and intracellular thermometers. Out of all methods to produce NDs with SiV − centers, ion implantation offers the unique potential to create controllable numbers of color centers in preselected individual NDs. However, the formation of single color centers in NDs with this technique has not been realized. We report the creation of single SiV − centers featuring stable high-purity single-photon emission through Si implantation into NDs with an average size of ∼20 nm. We observe room temperature emission, with zero-phonon line wavelengths in the range of 730–800 nm and linewidths below 10 nm. Our results offer new opportunities for the controlled production of group-IV diamond color centers with applications in quantum photonics, sensing, and biomedicine. 

   more » « less
4. Field programmable spin arrays for scalable quantum repeaters

   https://doi.org/10.1038/s41467-023-36098-8  

   Wang, Hanfeng; Trusheim, Matthew E.; Kim, Laura; Raniwala, Hamza; Englund, Dirk R. (December 2023, Nature Communications)

   Abstract The large scale control over thousands of quantum emitters desired by quantum network technology is limited by the power consumption and cross-talk inherent in current microwave techniques. Here we propose a quantum repeater architecture based on densely-packed diamond color centers (CCs) in a programmable electrode array, with quantum gates driven by electric or strain fields. This ‘field programmable spin array’ (FPSA) enables high-speed spin control of individual CCs with low cross-talk and power dissipation. Integrated in a slow-light waveguide for efficient optical coupling, the FPSA serves as a quantum interface for optically-mediated entanglement. We evaluate the performance of the FPSA architecture in comparison to a routing-tree design and show an increased entanglement generation rate scaling into the thousand-qubit regime. Our results enable high fidelity control of dense quantum emitter arrays for scalable networking. 

   more » « less
5. Single-Shot Readout and Weak Measurement of a Tin-Vacancy Qubit in Diamond

   https://doi.org/10.1103/PhysRevX.14.041008  

   Rosenthal, Eric I; Biswas, Souvik; Scuri, Giovanni; Lee, Hope; Stein, Abigail J; Kleidermacher, Hannah C; Grzesik, Jakob; Rugar, Alison E; Aghaeimeibodi, Shahriar; Riedel, Daniel; et al (October 2024, Physical Review X)

   The negatively charged tin-vacancy center in diamond ( ${\mathrm{SnV}}^{-}$) is an emerging platform for building the next generation of long-distance quantum networks. This is due to the ${\mathrm{SnV}}^{-}$’s favorable optical and spin properties including bright emission, insensitivity to electronic noise, and long spin coherence times at temperatures above 1 K. Here, we demonstrate measurement of a single ${\mathrm{SnV}}^{-}$electronic spin with a single-shot readout fidelity of 87.4%, which can be further improved to 98.5% by conditioning on multiple readouts. In the process, we develop understanding of the relationship between strain, magnetic field, spin readout, and microwave spin control. We show that high-fidelity readout is compatible with rapid microwave spin control, demonstrating a favorable parameter regime for use of the ${\mathrm{SnV}}^{-}$center as a high-quality spin-photon interface. Finally, we use weak quantum measurement to study measurement-induced dephasing; this illuminates the fundamental interplay between measurement and decoherence in quantum mechanics, and provides a universal method to characterize the efficiency of color-center spin readout. Taken together, these results overcome an important hurdle in the development of the ${\mathrm{SnV}}^{-}$-based quantum technologies and, in the process, develop techniques and understanding broadly applicable to the study of solid-state quantum emitters. Published by the American Physical Society2024 

   more » « less