Quantum Coherence Applications in Modular Computing

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

IBM Successfully Links Two Quantum Chips to Operate as a Single Device Key Insights: • IBM has achieved a significant milestone by linking two quantum chips to function as a single, cohesive system, enabling them to perform calculations beyond the capability of either chip independently. • This accomplishment supports IBM’s modular approach to building scalable quantum computers, a strategy aimed at overcoming the limitations of single-chip architectures. • The linked chips demonstrated successful cooperation, marking a step closer to larger and more powerful quantum systems capable of addressing complex real-world problems. The Modular Quantum Computing Approach: • IBM employs superconducting quantum chips, manufactured using processes similar to traditional semiconductor technology, allowing scalability and integration with existing hardware infrastructure. • Modular quantum systems involve linking smaller quantum processors, rather than relying on a single massive chip, reducing fabrication challenges and improving scalability. • This architecture allows multiple chips to share quantum information seamlessly, paving the way for constructing larger quantum systems without exponentially increasing hardware complexity. Addressing Key Challenges in Quantum Computing: • Scalability: Connecting multiple chips is a critical step toward scaling quantum computers to thousands or even millions of qubits. • Error Reduction: Larger quantum systems increase susceptibility to errors. Modular architectures provide pathways for better error management and correction across linked processors. • Coherence Across Chips: Maintaining the delicate quantum states across separate chips is technically challenging, and IBM’s success suggests progress in solving this issue. Implications of IBM’s Achievement: • Enhanced Computational Power: Linked quantum chips unlock the potential for more complex simulations and problem-solving capabilities. • Practical Quantum Applications: Industries like pharmaceuticals, cryptography, and materials science may soon benefit from more robust and scalable quantum computing solutions. • Competitive Advantage: IBM’s progress underscores its leadership in modular quantum computing, positioning it strongly in the competitive quantum technology landscape. Future Outlook: IBM’s successful demonstration of inter-chip quantum communication validates the modular quantum computing strategy as a viable path to scaling up systems. Future advancements will likely focus on enhancing chip-to-chip communication fidelity, increasing the number of interconnected chips, and reducing overall error rates. This breakthrough brings us one step closer to practical, large-scale quantum computing systems capable of solving problems previously deemed unsolvable by classical computers.

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

Researchers in the United States say a superconducting qubit now holds its state for more than a millisecond, long enough to change how we think about useful quantum circuits. The result pushes lab records and nudges industrial roadmaps toward designs that look manufacturable rather than bespoke. Coherence time sets the clock for everything a quantum processor can do. The longer a qubit keeps its state, the more gates it can run before noise wins. Princeton University’s team reports a coherence beyond 1 millisecond in a 2D transmon, with single‑qubit gate fidelity measured at 99.994%. That combination starts to look like the foundation of a practical machine rather than a one‑off stunt. The jump is meaningful in context. According to the team, the new device stretches coherence roughly three times beyond the best recent lab numbers and around fifteen times beyond typical industrial hardware today. That headroom multiplies circuit depth, trims error budgets, and reduces how aggressively systems must invoke error correction just to stay upright. The group led by Andrew Houck swapped the usual aluminium in the qubit’s superconducting circuitry for tantalum, and traded sapphire substrates for high‑grade silicon. Tantalum’s surface chemistry tends to host fewer loss‑inducing defects, while silicon opens the door to wafer‑scale processing and the tools the chip industry already trusts. Gluing those pieces together took a lot of hard yards. Growing clean tantalum films directly on silicon, taming the interfaces, and keeping parasitic losses low demanded precise control at the atomic scale. The pay‑off is a simple stack that fits today’s fabrication lines. The team reports coherence beyond 1 ms and single‑qubit gates at 99.994% fidelity on a fully functioning chip, not just an isolated test structure. That matters for scale: a design that slots into existing control electronics and readout hardware stands a far better chance of growing from a handful of qubits to thousands. This is still a superconducting transmon, so it aligns with the architecture used by Google, IBM, and others. The researchers argue that dropping such qubits into established layouts could lift effective performance dramatically — they suggest up to a thousandfold in some regimes — because coherence multiplies through layers of computation. The claim needs broad replication, but the reasoning tracks the math of circuit depth and error accumulation. Read more here —> https://lnkd.in/gSRcWrcm #quantum #computing #coherence #control #electronics #performance #record