Quantum Link Communication Techniques

Single-Photon Teleportation Between Distant Quantum Dots Achieved for the First Time In a landmark advance toward a functional quantum internet, European researchers have teleported the polarization state of a single photon from one semiconductor quantum dot to another physically separate dot—something never before accomplished. This breakthrough shows that quantum dots can serve as scalable, deterministic building blocks for future ultra-secure communication networks. Key Developments • The experiment teleported a photon’s polarization across a 270-meter free-space optical link between two university buildings, using independent quantum dots rather than photons generated from the same emitter. • Achieving teleportation with dissimilar emitters removes a long-standing roadblock to building quantum relays and repeaters, which are essential for long-distance quantum networking. • The teleportation fidelity reached 82 percent—exceeding the classical limit by more than 10 standard deviations—thanks to GPS timing synchronization, ultra-fast photon detectors, and atmospheric-turbulence stabilization. • The result reflects a decade of coordinated European research in materials science, nanofabrication, and optical quantum engineering, with contributions from Paderborn, Rome, Linz, Würzburg, and others. • A parallel team in Stuttgart and Saarbrücken reported a similar result through frequency conversion, signaling rapid progress across Europe. Broader Implications This achievement sets the stage for the next major milestone: entanglement swapping between two quantum dots—the first true quantum relay using deterministic photon sources. Such systems would allow quantum information to hop across networks without loss, forming the backbone of future quantum communication, secure data channels, and distributed quantum computing. The demonstration proves that quantum-dot-based devices can interoperate across real-world optical links, marking a decisive step toward a scalable quantum internet. I share daily insights with 35,000+ followers across defense, tech, and policy. If this topic resonates, I invite you to connect and continue the conversation. Keith King https://lnkd.in/gHPvUttw

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

Researchers at Northwestern University (USA) have made a significant breakthrough in quantum communication by successfully teleporting a quantum state of light—a qubit carried by a photon—through approximately 30 kilometers of optical fiber while simultaneously transmitting high-speed classical data traffic. Key details include: - The fiber length used was around 30.2 km. - It carried a classical signal of approximately 400 Gbps in the C-band alongside the quantum channel. - The quantum channel operated in the O-band, utilizing special filtering and narrow-temporal/spectral techniques to shield delicate photons from noise, such as spontaneous Raman scattering from the classical channel. This experiment confirms that quantum teleportation of a quantum state can coexist with classical internet traffic in the same fiber infrastructure. It's important to clarify that "teleportation" in quantum communication does not involve moving the physical photon or "beaming" objects as depicted in science fiction. Instead, it refers to the transfer of the quantum state of a qubit from one location to another using an entanglement-based protocol, coupled with classical communication. The original qubit is destroyed during this process and recreated at the destination. While quantum teleportation enables inherently secure quantum communication channels—since measurement disturbs quantum states—practical deployment still faces challenges, including node security, classical channel security, side-channels, and error rates. This marks a significant step toward quantum-secure networks, though it is not yet a complete "unhackable" solution. This experiment suggests that we may not require entirely separate fiber infrastructure dedicated solely to quantum communications; existing telecom fiber could be effectively utilized. It enhances the feasibility of developing quantum networks and, eventually, a "quantum internet" that integrates with classical infrastructure. From a security and cyber perspective, it supports the architecture of quantum-secure communications, including quantum key distribution and entanglement-based signaling. Overall, this represents a major technological milestone in photonics, quantum information science, and telecom integration.

Quantum Teleportation: Now Five Channels at Once Let’s be clear right away — nobody “teleported” anywhere. Quantum teleportation doesn’t move matter. It transfers information about a particle’s quantum state from point A to point B, using two resources: quantum entanglement and an ordinary classical signal. No sci-fi — just physics. But physics that could become the foundation of a next-generation communications network. The problem is that, until now, this kind of transfer has worked, roughly speaking, one channel at a time. Imagine an internet where you can send only one email, wait for confirmation, and only then send the next one. You can’t build a powerful communications system that way — you need parallelism. A team at Shanxi University has now demonstrated the simultaneous teleportation of five quantum channels — so-called sideband qumodes — within a 24 MHz bandwidth. A qumode is a separate frequency mode of an optical field — basically an independent “stream” of information inside a single beam of light. The key idea is precise phase tuning of two classical communication channels at different, adjustable frequencies. Thanks to that, the researchers didn’t just teleport several states in parallel — they also managed to control how many channels were transmitted in each individual run. Want three? Fine. Five? Also possible. A flexibility that wasn’t available before. The transmission fidelity was about 70%, and all results surpassed the so-called no-cloning limit — the threshold below which teleportation could be explained using classical methods. Above that threshold, it can only be genuine quantum transfer. The practical takeaway is straightforward: if you can pack more quantum information into a single physical system without building a separate setup for every channel, that’s a real step toward scalable quantum communication networks. https://lnkd.in/eQJwKjEd

Check out the latest from MIT EQuS and Lincoln Laboratory published in @NaturePhysics! In this work, we demonstrate a quantum interconnect using a waveguide to connect two superconducting, multi-qubit modules located in separate microwave packages. We emit and absorb microwave photons on demand and in a chosen direction between these modules using quantum entanglement and quantum interference. To optimize the emission and absorption protocol, we use a reinforcement learning algorithm to shape the photon for maximal absorption efficiency, exceeding 60% in both directions. By halting the emission process halfway through its duration, we generate remote entanglement between modules in the form of a four-qubit W state with concurrence exceeding 60%. This quantum network architecture enables all-to-all connectivity between non-local processors for modular, distributed, and extensible quantum computation. Read the full paper here: https://lnkd.in/eN4MagvU (paywall), view-only link https://rdcu.be/eeuBF, or arXiv https://lnkd.in/ez3Xz7KT. See also the related MIT News article: https://lnkd.in/e_4pv8cs. Congratulations Aziza Almanakly, Beatriz Yankelevich, and all co-authors with the MIT EQuS Group and MIT Lincoln Laboratory! Massachusetts Institute of Technology, MIT Center for Quantum Engineering, MIT EECS, MIT Department of Physics, MIT School of Engineering, MIT School of Science, Research Laboratory of Electronics at MIT, MIT Lincoln Laboratory, MIT xPRO, Will Oliver

Quantum teleportation coexisting with classical communications in optical fiber https://lnkd.in/gcSWCpup Abstract: The ability for quantum and conventional networks to operate in the same optical fibers would aid the deployment of quantum network technology on a large scale. Quantum teleportation is a fundamental operation in quantum networking, but has yet to be demonstrated in fibers populated with high-power conventional optical signals. Here we report, to the best of our knowledge, the first demonstration of quantum teleportation over fibers carrying conventional telecommunications traffic. Quantum state transfer is achieved over a 30.2-km fiber carrying 400-Gbps C-band classical traffic with a Bell state measurement performed at the fiber’s midpoint. To protect quantum fidelity from spontaneous Raman scattering noise, we use optimal O-band quantum channels, narrow spectro-temporal filtering, and multi-photon coincidence detection. Fidelity is shown to be well maintained with an elevated C-band launch power of 18.7 dBm for the single-channel 400-Gbps signal, which we project could support multiple classical channels totaling many terabits/s aggregate data rates. These results show the feasibility of advanced quantum and classical network applications operating within a unified fiber infrastructure.

US researchers have achieved quantum teleportation over 30 kilometers using standard internet fiber optic cables, a major step towards secure quantum networks. This process used entangled particles to transmit quantum states while coexisting with regular internet traffic, proving compatibility between quantum and classical communication. The breakthrough, published in Optica, eliminates the need for costly infrastructure, paving the way for advanced applications in quantum computing, faster data sharing, and highly secure communication systems. This milestone demonstrates the practicality of integrating quantum technology into existing networks. Source – ZME Science I have regularly been critical of quantum computing, but there's another area of quantum mechanics - entanglement - that I think holds far more potential short term. Entanglement (aka spooky action at a distance, according to Einstein) causes two particles to effectively act as if they were the same particle (bosons), even when separated by sizeable distances. If you influence one particle, the other particle will change state without any intervening transmission, and this change of state (such as polarity, can then be detected). This experiment showed that you can transmit one of a pair of such particles across coaxial cables and maintain entanglement. The upshot of this is very interesting, because it means that messages can be send point to point without having to be routed through a complex network. Not only would this have a huge impact upon the speed of such systems, but the communication would be completely secure as there is no possibility of a man-in-the-middle type effect. It also reduces the need for big cryptographic keys, and futureproofs against quantum decoding.

In a First, Scientists Sent Quantum Messages a Record Distance Over a Traditional Network - MSN Scientists have sent quantum information across a record-breaking 158 miles using ordinary computers and fiber-optic cables. It is the first time coherent quantum communication—an ultrasecure means of transmitting data—has been achieved using existing telecommunications infrastructure, without the expensive cryogenic cooling that is typically required. “Our equipment was running alongside the fibers that we use for regular communication literally buried underneath the roads and train stations,” said Mirko Pittaluga, a physicist and lead author of a study published Wednesday in Nature describing the work. Integrating the technology into existing infrastructure using largely off-the-shelf equipment is a key step in expanding the accessibility of quantum communication and its use in encrypting information for more secure transmission of data, according to multiple physicists and engineers who weren’t involved in the study. “This is about as real-world as one could imagine,” said David Awschalom, a professor of physics and molecular engineering at the University of Chicago who wasn’t a part of the new work. “It’s an impressive, quite beautiful demonstration.” Classical digital information is communicated over the internet in units known as bits that have fixed values of 1 or 0. In contrast, quantum information is transmitted in qubits, which can store multiple values at once, making quantum communications more secure. Pittaluga and his colleagues at Toshiba Europe sent quantum information from regular computers hooked into the telecommunications network at data centers in the German cities of Kehl and Frankfurt, relaying them through a detector at a third data center roughly midway between them in Kirchfeld. The three-location setup enabled the group to extend the distance the messages were sent more than 150 miles, an uninterrupted distance only ever achieved in a laboratory environment. Working at these types of distances, Awschalom said, means that quantum information could be sent across entire metropolitan areas or between nearby cities, making it useful for hospitals, banks and other institutions, for which secure communications are paramount. #cybersecurity #tradtitional #networking #quantumcomputing #qubits #securecommunications

𝐐𝐔𝐀𝐍𝐓𝐔𝐌 𝐒𝐄𝐂𝐔𝐑𝐄 𝐔𝐍𝐈𝐓𝐘 — 𝐓𝐡𝐞 𝐀𝐫𝐢𝐬𝐢𝐧𝐠 𝐈𝐧𝐭𝐞𝐥𝐥𝐢𝐠𝐞𝐧𝐜𝐞 𝐍𝐞𝐭𝐰𝐨𝐫𝐤 Standing at the convergence of quantum physics, cryptographic science, autonomous systems, and secure communications, we are witnessing something extraordinary. Twin-Field Quantum Key Distribution (TF-QKD) is more than a protocol — it is a redefinition of secure communication. A channel where photons become truth carriers, where trust is validated by quantum interference, and where distance is no longer the enemy of confidentiality. In traditional systems, security declines as distance increases. With TF-QKD, the relationship is reversed. Using single-photon interference and phase-matched coherent signals, it generates secure keys at rates that scale with the square root of transmission efficiency. This allows secure quantum communication to expand beyond the classical bounds — breaking the long-standing repeaterless limit without the complexity of quantum memories or repeaters. Today we are generating quantum-secure keys across hundreds of kilometers of optical fiber, proving that unbreakable channels can span national lines, strategic infrastructures, and future global networks. This is not merely a cryptographic upgrade. It is the beginning of quantum-secure intelligence. TF-QKD enables authentication and control for autonomous agents, robotic systems, distributed AI models, and critical decision networks — all protected not by encryption strength, but by the laws of physics. Spoofing, interception, and man-in-the-middle attacks are eliminated not through defense but through impossibility. Photonic security becomes the backbone for emerging machine cognition. AI-powered swarms, autonomous decision engines, and future intelligence architectures require secure neural pathways, not just encrypted channels. TF-QKD provides that pathway — a quantum-verified trust fabric that no adversary, algorithm, or future quantum machine can decode or manipulate. This is no longer about cybersecurity. It is about securing cognition. Not about protecting networks — but protecting intelligence itself. As we build the future of AI, robotics, quantum systems, and secure infrastructure, we must also build the trust layer that unites them. TF-QKD is that layer. The quantum bridge is open. What we choose to send across it will define the future. #changetheworld