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We’re pushing the boundaries of what’s possible, from fundamental breakthroughs to applied innovations in quantum communication and entanglement.
Nano Letters, 2025
Solid-state spin-based quantum systems have emerged as popular platforms for quantum networking applications due to their optical interfaces, their long-lived quantum memories, and their natural compatibility with semiconductor manufacturing. Photonic crystal cavities are often used to enhance radiative emission; however, fabrication of the necessary subwavelength cavities is typically limited to small batch electron beam lithography. In this work, we demonstrate high quality factor, small mode volume nanobeam cavities fabricated on a scalable silicon photonic foundry platform. The foundry fabricated cavities are then interfaced with single erbium ions through backend deposition of TiO2 thin films lightly doped with erbium. Single ion lifetime measurements indicate Purcell enhancement up to about 500, thereby demonstrating a route toward manufacturable deterministic single photon sources in the telecom C-band.
J. Appl. Phys. 136, 124402 (2024)
Rare-earth ion doped oxide thin films integrated on silicon substrates provide a route toward scalable, chip-scale platforms for quantum coherent devices. Erbium-doped is an attractive candidate: the optical transition is compatible with C-band optical fiber communications, while is an insulating dielectric compatible with silicon process technology. Through structural and optical studies of Er-doped thin films grown via molecular beam deposition on silicon, , and sapphire substrates, we have explored the impact of polycrystallinity and microstructure on the optical properties of the Er emission. Comparing polycrystalline (rutile)/Si with single-crystalline (rutile)/r-sapphire and polycrystalline (anatase)/Si with single-crystalline (anatase)/ , we observe that the inhomogeneous linewidth ( ) of the most prominent peak in the Er spectrum (the – transition, 1520 and 1533 nm in rutile and anatase ) is significantly narrower in the polycrystalline case. This implies a relative insensitivity to extended structural defects and grain boundaries in such films (as opposed to, e.g., point defects). We show that the growth of an undoped, underlying buffer on Si can reduce by a factor of 4–5. Expectedly, also reduces with decreasing Er concentrations: we observe a 2 order of magnitude reduction from 1000 ppm Er to 10 ppm Er. then gets limited to a residual value of 5 GHz that is insensitive to further reduction in the Er concentration. Based upon the above results, we argue that the optical properties in these thin films are limited by the presence of high “grown-in” point defect concentrations.
Appl. Phys. Lett. 125, 084001 (2024)
Defects and dopant atoms in solid state materials are a promising platform for realizing single photon sources and quantum memories, which are the basic building blocks of quantum repeaters needed for long distance quantum networks. In particular, trivalent erbium (Er3+) is of interest because it couples C-band telecom optical transitions with a spin-based memory platform. In order to produce quantum repeaters at the scale required for quantum networks it is imperative to integrate these necessary building blocks with mature and scalable semiconductor processes. In this work, we demonstrate the optical isolation of single Er3+ ions in CMOS-compatible titanium dioxide (TiO2) thin films monolithically integrated on a silicon-on-insulator photonics platform. Our results demonstrate an initial step toward the realization of a monolithically integrated and scalable quantum photonics package based on Er3+ doped thin films.
Advanced Optical Materials , 12, 2401101 (2024)
Silicon carbide (SiC)’s nonlinear optical properties and applications to quantum information have recently brought attention to its potential as an integrated photonics platform. However, despite its many excellent material properties, such as large thermal conductivity, wide transparency window, and strong optical nonlinearities, it is generally a difficult material for microfabrication. Here, it is shown that directly bonded silicon-on-silicon carbide can be a high-performing hybrid photonics platform that does not require the need to form SiC membranes or directly pattern in SiC. The optimized bonding method yields defect-free, uniform films with minimal oxide at the silicon–silicon–carbide interface. Ring resonators are patterned into the silicon layer with standard, complimentary metal–oxide–semiconductor (CMOS) compatible (Si) fabrication and measure room-temperature, near-infrared quality factors exceeding 105. The corresponding propagation loss is 5.7 dB cm−1. The process offers a wafer-scalable pathway to the integration of SiC photonics into CMOS devices.
Appl. Phys. Rev. 10, 031307 (2023)
The ultimate realization of a global quantum internet will require advances in scalable technologies capable of generating, storing, and manipulating quantum information. The essential devices that will perform these tasks in a quantum network are quantum repeaters, which will enable the long-range distribution of entanglement between distant network nodes. In this review, we provide an overview of the primary functions of a quantum repeater and discuss progress that has been made toward the development of repeaters with rare-earth ion doped materials while noting challenges that are being faced as the technologies mature. We give particular attention to erbium, which is well suited for networking applications. Finally, we provide a discussion of near-term benchmarks that can further guide rare-earth ion platforms for impact in near-term quantum networks.
We review approaches to achieve high-rate entanglement photonic entanglement (>10 kHz) between atoms in two separate quantum computing modules in a datacenter-like scheme. Emissive qubit schemes are discussed, as these are most amenable to broad implementation in a qubit-agnostic and extensible network architecture.
Huge congratulations to our friends at PsiQuantum on officially breaking ground for their new facility at the Illinois Quantum and Microelectronics Park. Illinois Gov. JB Pritzker was joined by leading quantum business, research, academic, and government institutions to celebrate the groundbreaking of the facility located at the Quantum Shore on Chicago’s South SIde. As a seed-stage company, this is a monumental validation. This new hub accelerates the entire ecosystem, which is crucial for our mission at memQ.
Read more here.
memQ is pleased to share that our Quantum Networking Bootcamp at Quantum World Congress was a major success, bringing together an audience of both academic and enterprise technologists to really dig into how to accomplish quantum networking. The strong engagement and rich line of questioning confirms the appetite for knowledge, guidance, and early deployments – and strengthens our pipeline of collaborators!
Simulation enables memQ to mimic complex interactions at the atomic level, and such precision is crucial for the development of reliable and scalable quantum networks. memQ’s approach to using simulation tools involves initial in-house fabrication and short feedback loops to refine their designs. Once they are confident in their simulations, they proceed to external foundries for more extensive fabrication.
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CHICAGO, Aug. 20, 2025 memQ announced today the appointment of Professor David Awschalom to the company’s advisory board. Professor Awschalom is a globally recognized pioneer in the field of quantum science and currently serves as a distinguished professor at the University of Chicago as well as holding the position of senior scientist at Argonne National Laboratory.
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CHICAGO, IL, July 31, 2025 memQ™, the industry leader in quantum networking solutions for distributed quantum computing, today announced breakthrough technology and processes that allow scalable and cost-effective production of quantum networking components using common semiconductor production capabilities. This approach, now used in their xQNA quantum memory modules, has been demonstrated as compatible with large-scale 300 mm silicon wafer processing to deliver truly scalable single photon sources supporting the ubiquitous telecom C-band.
Read the full article here.
See the full peer reviewed work in Nanoletters.
Quantum computing has captured the investment attention of the tech sector over the past few years, with estimates exceeding $60B to realize the incredible power and promise of quantum. Recently, however, it has become apparent that quantum networking – the ability to connect quantum systems in a way that doesn’t collapse the quantum state – will be key to realizing this potential. With this, quantum networking is quickly becoming seen as its own market segment, supportive of but distinct from quantum computing and sensing. Recent market data and investment flows show that secure entanglement links are moving from research labs into commercial pilots and use-cases, attracting carriers, cloud providers, and dedicated start‑ups to what is expected be a multi-billion dollar market segment in its own right.
Classical computing networks evolved from monolithic ‘walled gardens’ performing very specific functions to flexible, multi‑layered infrastructures capable of supporting an array of workloads across billions of users. In order to achieve broad commercial adoption and fulfill the promise of harnessing quantum physics, quantum systems must grow past today’s self-contained entanglement schema if they are to achieve quantum advantage across a range of workloads and solutions. These powerful systems will need to be able to network on demand with other quantum systems in a manner that preserves the quantum state (i.e. entanglement) allowing qubit power to be delivered as/when needed in a way that’s secure, scalable, and modular. This article touches on the staged evolution of quantum networking, and key developments and workloads at each stage.
Distributed quantum computing is here, and it’s changing the way we think about scaling quantum computers. As labs achieve higher fidelity gate operations and scale to larger quantum volumes, we’re seeing companies across all qubit technologies: superconducting, trapped ion, photonic, neutral atoms, and others recognize this fundamental shift towards modular distributed quantum computing.
