Quantum Technology Initiatives

World-First Photon Router Bridges Quantum Computers and Fiber Networks Harvard and Partners Develop Key Technology for Scalable Quantum Networks In a groundbreaking advancement for quantum communication, scientists at Harvard’s School of Engineering and Applied Sciences (SEAS), along with collaborators from Rigetti Computing, MIT, and the University of Chicago, have developed the world’s first functional photon router capable of linking noise-sensitive microwave quantum computers to global fiber-optic networks. This innovation is seen as a critical step toward building scalable, real-world quantum internet infrastructure. The Quantum Network Challenge • Quantum Computers Need Quantum Networks • Quantum computers operate on qubits, which are highly sensitive quantum states requiring ultra-low temperatures to remain stable and coherent. • While practical in controlled lab environments, these extreme conditions are infeasible for long-range communication, preventing direct scaling into broad networks. • Photon-Based Communication as the Solution • Unlike qubits, photons—light particles—can carry quantum information across fiber-optic cables over great distances with minimal degradation. • The challenge is enabling quantum computers, which operate using microwave signals, to exchange information using optical photons. Introducing the Microwave-Optical Quantum Transducer • What It Is and What It Does • The new device functions as a photon router, converting fragile microwave signals from quantum processors into optical photons that can travel through existing telecom networks. • It enables quantum systems to interface with classical infrastructure without disturbing the quantum data. • Technical Feat and Real-World Application • The device preserves quantum coherence while translating between two radically different energy domains: microwaves (used inside quantum computers) and optical frequencies (used in fiber-optic networks). • This microwave-optical transduction is essential for establishing quantum repeaters and routers, key components of a quantum internet. Broader Implications for Quantum Technology • Unlocking a Scalable Quantum Internet • The photon router could allow quantum computers in different locations to share entangled states, conduct distributed quantum computing, and enable secure quantum communication over long distances. • This advancement paves the way for a modular quantum computing architecture, in which multiple quantum processors work together via a shared network. • Positioning the U.S. at the Forefront • With government and industry alike pushing to secure technological leadership in quantum systems, this innovation places U.S. research institutions and startups ahead in developing quantum-compatible communication layers.

Under the streets of Manhattan and Brooklyn. Through 60 Hudson, one of the most connected carrier hotels in the world. Real quantum entanglement at scale on 17.6 km of standard telecom fiber. With swapping rates 3+ orders of magnitude beyond prior efforts and fidelity above 99%. This is the full quantum networking stack coming together — hardware, protocol, control, orchestration. Most importantly, we ran this without the shared laser crutch that makes lab experiments unscalable by design. This real-world demo used fully independent quantum sources at each endpoint. With Cisco's quantum software stack handling timing coordination at picosecond precision across three geographically separated nodes using the White Rabbit protocol. Qunnect's room-temperature hardware at the edges. And cryogenic equipment only at the hub for efficiency. Any new nodes could be added to this network without touching the sync infrastructure. And with clean control and data plane separation.   Applying design patterns that scaled the classical internet to quantum networking. I wrote about what this milestone means and how it leads us one step closer to our vision of a quantum data center network, on the Cisco blog today. 🔗 Link in comments. 📸 Photo of Manhattan from the Brooklyn end, by me.

⚛️ Quantum Networking Fundamentals: From Physical Protocols to Network Engineering 📜 The realization of the Quantum Internet promises transformative capabilities in unconditionally secure communication, distributed quantum computing, and high-precision quantum metrology. However, transitioning from isolated laboratory experiments to a scalable, multi-tenant network utility introduces deep orchestration challenges. Current development is largely siloed within the physics and optics communities, prioritizing hardware fidelities and photon sources, while theclassical networking community lacks the architectural models required to dynamically manage these fragile quantum resources. This tutorial bridges this disciplinary divide by providing a comprehensive, network-centric view of quantum networking. We systematically dismantle the idealized assumptions prevalent in current network simulators to directly address the “simulation–reality gap,” and we recast them as explicit control-plane constraints. To bridge this gap, we establish Software-Defined Quantum Networking (SDQN) not merely as an evolutionary management tool, but as a mandatory prerequisite for scale, and we prioritize the orchestration of a symbiotic, dual-plane architecture in which classical control dictates quantum data flow. Specifically, we synthesize reference models for SDQN and the Quantum Network Operating System (QNOS) for hardware abstraction, and we adapt a Quantum Network Utility Maximization (Q-NUM) framework as a unifying mathematical lens to help network engineers reason about the inherent trade-offs between entanglement routing, scheduling, and fidelity targets. Furthermore, we analyze Distributed Quantum AI (DQAI) over imperfect networks as a case study, illustrating how physical constraints such as probabilistic stragglers and decoherence fundamentally dictate application-layer viability. Ultimately, this tutorial equips network engineers with the operational mindset and architectural tools required to transition quantum networking from a bespoke physics experiment into a programmable, multi-tenant global infrastructure. ℹ️ A. Gkelias et al - EEE Department, Imperial College, London, UK -2026

From NVLink to NVQLink: Wiring Quantum Processors into AI Supercomputers NVIDIA just unveiled NVQLink - an open interconnect + software stack that tightly couples quantum processors (QPUs) with AI supercomputers for real-time hybrid workflows like calibration and quantum error correction (QEC). It's not a quantum computer from NVIDIA, it's the missing fast path between QPUs and today's accelerated systems so the two can work as one. ✅ What is NVQLink exactly? A hardware + software integration path that links QPUs to NVIDIA GPU/CPU systems with low-latency, high-throughput data movement and real-time control via CUDA-Q (formerly CUDA-Quantum). Performance (NVIDIA-stated): up to 400 Gb/s GPU↔QPU throughput and <4 μs minimum round-trip latency in a reference (FPGA→GPU→FPGA) loop, sized for fast feedback tasks like QEC decoders and calibration. ✅ Why do we need NVQLink? Quantum isn't standalone: to be useful, QPUs depend on classical compute for: 🔹 Calibration and drift tracking, 🔹 Real-time QEC decoding and control, 🔹 Logical program orchestration (dynamic routing, lattice surgery, just-in-time compilation). All three are latency-critical control loops. NVQLink provides the speed/scale so GPUs can run these loops in real time while QPUs stay coherent. NVIDIA's message is hybrid is the future: supercomputers + QPUs co-evolve. quantum doesn't replace GPU systems. ✅ How does NVQLink work? 🔹 A QPU (the quantum chip) is driven by nearby control electronics that send precise pulses and read measurements. 🔹 NVQLink is the fast lane between that controller and the GPU, so results from the QPU reach the GPU in microseconds and new commands go back just as fast. 🔹 CUDA-Q is the programming layer: you write one hybrid program where the QPU does the quantum steps, and the GPU does the heavy classical math (like error-correction and optimization). 🔹 Inside the AI node, NVLink/NVSwitch connects GPU↔GPU at very high bandwidth. NVQLink connects QPU↔GPU for tight, real-time control. ✅ Where does it fit inside today's GPU systems? In a Blackwell/NVLink-5 cluster (or CPU+GPU nodes), GPUs already share data over NVLink/NVSwitch at TB/s. NVQLink brings the QPU/control side into that world: measurement results flow quickly to GPUs. GPU decoders/control kernels send decisions back within microseconds, the rest of the AI stack (simulation, scheduling, ML-based decoders) runs on the same accelerated node. Think of NVQLink as the southbridge to quantum: it's the tight, deterministic path between the quantum device and the GPU side where the heavy classical algorithms live. Nvidia NVQLink: https://lnkd.in/gYr4xZk3