Quantum Entanglement Stability in Practical Applications

Quantum Armor: Topological Skyrmions Offer Robust Protection for Entangled States New Method Could Revolutionize Quantum Stability and Data Integrity One of the greatest challenges in quantum computing and communication is the extreme fragility of quantum entanglement. A small disturbance from the surrounding environment—be it stray photons or particles—can destroy entangled states and compromise quantum information. Now, researchers at the University of the Witwatersrand in Johannesburg have introduced a promising solution: using topological structures called skyrmions to “shield” quantum information, even in delicate entangled forms. Understanding the Breakthrough • The Problem: Noise Destroys Quantum States • Quantum entanglement enables particles to share states across any distance, a phenomenon Albert Einstein called “spooky action at a distance.” • However, entangled particles are notoriously sensitive. External noise—from temperature fluctuations to light interference—can easily collapse their quantum connection. • The Solution: Topological Encoding with Skyrmions • The research team proposes using quantum skyrmions—stable, swirling topological structures—as containers for quantum information. • Skyrmions have been observed in magnetic materials and quantum systems and are known for their durability and resistance to deformation. • Topology, the mathematical study of shapes and their preserved properties under continuous deformation, enables these structures to maintain coherence even in noisy environments. • How It Works • Quantum information is embedded within the skyrmion’s stable configuration, which resists environmental interference. • Because the information is stored in the topology rather than just the state of individual particles, it remains intact even as local disturbances occur. Why This Is a Game-Changer • Enhanced Quantum Stability • Encoding entangled information in topological skyrmions offers a potential path to longer-lasting, noise-resistant quantum systems. • This is especially critical for building scalable quantum computers and secure quantum communication networks. • A Step Toward Topological Quantum Computing • The findings align with broader research into topological quantum computing, a model that seeks to build fault-tolerant quantum systems based on topologically protected states. The Broader Impact This discovery represents a major advance in the field of quantum information science. By leveraging the inherent stability of topological skyrmions, researchers have introduced a new “quantum armor” that could make future quantum systems more reliable and practical. As quantum technologies continue to evolve, such protective methods will be essential for turning theory into real-world applications—from unbreakable encryption to ultra-powerful computation. The road to robust quantum systems just became clearer—and significantly more resilient.

Breakthrough for the #quantum internet: For the first time a major telco provider has successfully conducted entangled photon experiments - on its own infrastructure. ➡️ 30 kilometers, 17 days, 99 per cent fidelity. Our teams at T-Labs have successfully transmitted entangled photons over a fiber-optic network. Over a distance comparable to travelling from Berlin to Potsdam. The system automatically compensated for changing environmental conditions in the network.   Together with our partner Qunnect we have demonstrated that quantum entanglement works reliably. The goal: a quantum internet that supports applications beyond secure point-to-point networks. Therefore, it is necessary to distribute the types of entangled photons. The so-called qubits, that are used for #QuantumComputing, sensors or memory. Polarization qubits, like the ones used for this test, are highly compatible with many quantum devices. But: they are difficult to stabilize in fibers.   From the lab to the streets of Berlin: This success is a decisive step towards the quantum internet. 🔬 It shows how existing telecommunications infrastructure can support the quantum technologies of tomorrow. This opens the door to new forms of communication.   Why does this matter for people and society?   🗨️ Improved communications: The quantum internet promises faster and more efficient long-distance communications. 🔐 Maximum security: Entanglement can be used in quantum key distribution protocols. Enabling ultra-secure communication links for enterprises and government institutions 💡Technological advancement: high-precision time synchronization for satellite networks and highly accurate sensing in industrial IoT environments will need entanglement.   Developing quantum technologies isn’t just a technical challenge. A #humancentered approach asks how these systems can be built to serve real needs and be part of everyday infrastructure. With 2025 designated as the International Year of Quantum Science and Technology, now is the time to move from research to readiness. Matheus Sena, Marc Geitz, Riccardo Pascotto, Dr. Oliver Holschke, Abdu Mudesir

I'm so so thrilled to see our first GothamQ paper formally published in my most favorite journal, PRX Quantum 🎉 (link at the end) I've published many papers as a grad student, postdoc, and now a group lead but this work is so unique to me. To be fully honest, for the first time I feel like we have done something really impactful! On the surface, this is a very simple work! We distributed entanglement in NYC. But in reality this paper is the result of 4 years of nonstop hard work of our physicists, engineers, and software developers. We had to invent and manufacture a new entanglement source that works at room temperature (hence actually useful for qu. networking) but has lots of advantages over all the other alternative options. We had to invent and manufacture the devices that very rapidly and with very low loss monitor the infrastructure for any imperfections. We had to write thousands of lines of codes so both devices work together automatically and without any need for manual optimization. And on top of all that we had to negotiate and build a quantum testbed in one of the world's most busy and chaotic cities. We did all that to prove one thing: Entanglement distribution is ready for prime time, beyond academic and research testbeds. The technology has reached a pivotal point where everything is robust and high quality for practical use cases by a much wider community than just quantum physicists. This shift is not only essential for us to be able to use entanglement for applications we already know of, but also to make it widely available for much more creative people than us to constantly think of use cases for quantum networks and entanglement links. I really hope if you are in this field, you enjoy reading this paper and as always don't hesitate to reach out to me for any questions. Goes without saying, this work is all thanks to our amazing team at Qunnect, and a huge congrats to all the authors Alexander Craddock, Anne Lazenby, Gabriel Bello Portmann, Rourke Sekelsky, Maël Flament https://lnkd.in/eteZNASt

Qunnect's team has demonstrated polarization entanglement between telecom photons and a room-temperature quantum memory. #Quantum memories are critical elements of entanglement-based quantum networks, enabling the storage and retrieval of quantum states. Our breakthroughs tackle major limitations of existing quantum platforms, which usually rely on cryogenic setups and vacuum apparatus. Room-temperature quantum memories and #entanglement sources, like those based on atoms of rubidium, offer practical solutions for quantum networking, repeaters, and distributed #quantumcomputing or #quantumsensing. As we continue advancing these technologies, we anticipate many further improvements: extending coherence times into the millisecond regime through specialized vapor cells, enhancing fidelity with optimized photon sources, and increasing efficiency via noise filtering techniques... All towards increasing the performances of our existing commercial units, including the #quantummemory we launched in 2021, and which remains, for now, the only commercially available quantum memory. Ultimately, our solutions pave the way for scalable, affordable, and reliable quantum infrastructure suited to real-world applications. > For all the details, check out our team's pre-print paper by Yang Wang, here: https://lnkd.in/eQn6_xUv > Or explore a deep-dive blog post from Qunnect’s CSO Mehdi Namazi, here: https://lnkd.in/eunnfKpf

Delighted to share some work we've been developing over the past months! 📄 🔗🔗 https://lnkd.in/enXEQdDc 🔗🔗 ✨ Building on our previous research [https://lnkd.in/eCjCDv2D], we've explored a new direction for modular quantum computing with surface codes. The focus is on whether emission-based hardware can support fault-tolerant quantum error correction. The question we set out to answer: 🤔 📡 Can we distribute entanglement across modules without relying on slow and noisy two-qubit gates? 🔗 Our earlier work showed emission-based platforms were feasible but limited to thresholds of 0.16 % ⚡ Is there a more efficient protocol path forward? Our approach: 🎯 We propose single-shot GHZ state generation — creating the entangled states needed for stabilizer measurements directly, without Bell-pair fusion. The optical setup generates Bell pairs, W states, and GHZ states by simply observing photon detection patterns. Benchmarking on realistic hardware: 🧪 #DiamondColorCenters #QuantumHardware 🔴 We modeled this for diamond color-center platforms (what experimentalists are actually building) 🔴 Full noise modeling includes photon loss, detector efficiency, and circuit-level errors 🔴 Both photon-number-resolving and standard detectors analyzed The findings: 📊 We're grateful for what the analysis reveals about this architecture with circuit-level noise: 💎 Threshold of 0.24 % with photon-number-resolving detectors 💎 Threshold of 0.19 % with standard detectors 💎 These thresholds scale with hardware improvements — unlike previous approaches that saturated Why this matters: 🛣️ #FaultTolerance #ModularQuantumComputing #QuantumErrorCorrection This work suggests a practical pathway toward scalable modular quantum computers using hardware that's already being developed in labs. The protocols require only modest enhancements to existing emission-based setups. Looking ahead: 🔮 #ExperimentalQuantum #QuantumNetworks #DistributedQuantum We hope these results help guide the experimental community's next steps. We've tried to provide clear hardware targets and realistic thresholds that could inform near-term implementations. Special thanks to our collaborators at QuTech, Keio University, and OIST for making this collaborative effort possible. 🙏 Daniel Bhatti, Rikiya Kashiwagi, David Elkouss, Kazufumi Tanji, Wojciech Roga, Masahiro Takeoka #QuantumComputing #SurfaceCode #Photonics #ColorCenters #QuantumErrorCorrection #ModularArchitectures #QuantumInternet

PASSING FRAGILE QUANTUM STATES BETWEEN SEPARATE PHOTON SOURCES OR TRUE QUANTUM TELEPORTATION? Quantum communication aims to enable secure transmission of information across large distances by exploiting the principles of quantum mechanics. A central protocol in this context is quantum teleportation, which allows the transfer of quantum states without requiring the physical transport of the particles themselves. The essence of this process lies in maintaining quantum coherence—the stable phase relationships among superposed states—which ensures that the delicate correlations defining the quantum information are preserved during transmission. When photons originate from distinct sources, the challenge becomes even more formidable: the quantum states must remain indistinguishable and their superposition structures intact, so that interference and entanglement can be reliably established. Without coherence, the fragile quantum information encoded in superposition collapses into classical noise, undermining the fidelity of teleportation. Thus, overcoming issues of indistinguishability and coherence is not simply a technical detail but the fundamental requirement for faithfully transferring quantum states between separate photon sources. Recent experimental work using semiconductor quantum dots (QDs) has addressed this challenge. Researchers demonstrated photonic quantum teleportation between photons emitted by two separate GaAs quantum dots. In this scheme, one QD acted as a single-photon source, while the other generated entangled photon pairs. The single photon was prepared in conjugate polarization states and interfaced with the biexciton emission of the entangled pair through a polarization-selective Bell state measurement. This process enabled the polarization state of the single photon to be teleported onto the exciton emission of the entangled pair. A significant technical obstacle was the frequency mismatch between the two photon sources. This was mitigated using polarization-preserving quantum frequency converters, which aligned the photons to telecommunication wavelengths. The experiment achieved remote two-photon interference with a visibility of 30(1)% and a post-selected teleportation fidelity of 0.721(33), exceeding the classical limit. These results indicate that quantum coherence and superposition were preserved across distinct sources, consistent with successful teleportation. Unlike classical communication, quantum protocols provide intrinsic security, as attempts to intercept signals introduce detectable disturbances. Thus, while challenges remain in scaling and improving fidelity, this work shows that quantum teleportation between distinct photon sources is not merely state transfer but genuine teleportation, marking a step toward practical quantum communication networks. # https://lnkd.in/eBN4PTeC

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.

I⚛️ Telecommunications fiber-optic and free-space quantum local area networks at the Air Force Research Laboratory 📑 s quantum computing, sensing, timing, and networking technologies mature, quantum network testbeds are being deployed across the United States and around the world. To support the Air Force Research Laboratory (AFRL)’s mission of building heterogeneous quantum networks, we report on the development of Quantum Local Area Networks (QLANs) operating at telecommunications-band frequencies. The multi-node, reconfigurable QLANs include deployed optical fiber and free-space links connected to pristine laboratory environments and rugged outdoor test facilities. Each QLAN is tailored to distinct operating conditions and use cases, with unique environmental characteristics and capabilities. We present network topologies and in-depth link characterization data for three such networks. Using photonic integrated circuit-based sources of entangled photons, we demonstrate entanglement distribution of time-energy Bell states across deployed fiber in a wooded environment. The high quality of the entanglement is confirmed by a Clauser-Horne-Shimony-Holt inequality violation of S = 2.700, approaching the theoretical maximum of S = 2.828. We conclude with a discussion of future work aimed at expanding QLAN functionality and enabling entanglement distribution between heterogeneous matter-based quantum systems, including superconducting qubits and trapped ions. These results underscore the practical viability of field-deployable, qubit-agnostic quantum network infrastructure. ℹ️ Sheridan et al - 2025

Researchers at the University of Vienna led by Philip Walther just pioneered the field of quantum mechanics and general relativity by measuring “the effect of the rotation of Earth on quantum entangled photons,” as stated in a press release. In the Vienna experiment, they used an interferometer, which is the most sensitive to rotations. Their unparalleled precision makes them the ultimate tool for measuring rotational speeds, limited only by the boundaries of classical physics. Interferometers employing quantum entanglement have the potential to break those bounds. If two or more particles are entangled, only the overall state is known, while the state of the individual particle remains undetermined until measurement. This can be used to obtain more information per measurement than would be possible without it. However, the promised quantum leap in sensitivity has been hindered by the extremely delicate nature of entanglement. Here is where the Vienna experiment made the difference. They built a giant optical fibre Sagnac interferometer and kept the noise low and stable for several hours. This enabled the detection of enough high-quality entangled photon pairs such to outperform the rotation precision of previous quantum optical Sagnac interferometers by a thousand. A significant hurdle the researchers faced was isolating and extracting Earth’s steady rotation signal. “The core of the matter lays in establishing a reference point for our measurement, where light remains unaffected by Earth’s rotational effect,” explained lead author Raffaele Silvestri. “Given our inability to halt Earth’s from spinning, we devised a workaround: splitting the optical fibre into two equal-length coils and connecting them via an optical switch”. By toggling the switch on and off, the researchers could effectively cancel the rotation signal at will, which also allowed them to extend the stability of their large apparatus. “We have basically tricked the light into thinking it’s in a non-rotating universe”, added Silvestri. Full Article: https://lnkd.in/gaDTZF9K #Quantum #Entanglement #Measurements The experiment was pictured drawing a fiber Sagnac interferometric scheme inside a magnifying inset starting from a local position (Vienna, Austria) of the rotating Earth.