Ensuring Coherence in Quantum Processor Networks

Quantum Leap: MIT Device Enables Photon-Based Communication Between Quantum Processors A New Framework for Scalable Quantum Computing In a major advancement toward building large-scale quantum computers, researchers at MIT have developed a groundbreaking interconnection device that allows direct, photon-based communication between multiple superconducting quantum processors. Published in Nature Physics, the innovation addresses a key bottleneck in quantum architecture—how to efficiently link qubits spread across different processors without degrading the fragile quantum information they carry. Overcoming the Quantum Network Challenge Just as classical computers rely on high-speed data transfers between components like CPUs and memory, quantum computers must eventually support inter-processor communication. But doing this reliably at scale has been a major hurdle. • Current Limitation: Most existing quantum interconnects use point-to-point connections—an architecture that requires information to hop between multiple nodes, introducing error with each transfer. • Quantum Decoherence Risk: These repeated transfers degrade the quantum states (qubits), limiting computational accuracy and scalability. • MIT’s Solution: The MIT team’s new interconnect device enables “all-to-all” communication, meaning each quantum processor can communicate directly with any other, bypassing intermediate nodes and minimizing error. How the New Device Works The MIT device uses microwave photons—light particles that operate at the same energy scale as superconducting qubits—to shuttle quantum information on demand between processors. • Photon Routing on Demand: The system enables quantum processors to send photons back and forth in specific, user-defined directions. • Superconducting Waveguide: A specialized superconducting wire acts as a waveguide, efficiently transporting microwave photons across the network. • Demonstrated Performance: The researchers successfully built a two-processor network that shared photons with high fidelity—offering proof of concept for scalable communication. Why This Is a Breakthrough Quantum computers promise to revolutionize fields such as cryptography, drug discovery, climate modeling, and materials science—but only if they can scale beyond a few dozen or hundred qubits. • Enabling Modular Quantum Systems: With this architecture, multiple smaller quantum processors can be linked into a much larger, modular quantum system without sacrificing performance. • Reduced Error Rates: Fewer intermediary hops mean lower decoherence and higher overall system reliability—a key concern in quantum computation. • Roadmap to Scalable Quantum Networks: This photon-based, directionally controllable interconnect may be foundational for future quantum data centers where processors are physically separated but tightly networked.

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 computers have the potential to solve complex problems that are beyond the capabilities of classical supercomputers. Current methods ("point-to-point" ) involve complex intermediary circuits, which introduce noise and loss. To overcome these challenges, Massachusetts Institute of Technology researchers have developed a new interconnect device that supports scalable, "all-to-all" communication. This allows all superconducting quantum processors in a network to communicate directly with each other. Key Takeaways: 💻 The new device supports scalable, "all-to-all" communication among quantum processors. ⚛️ Demonstrates remote entanglement, a key step toward developing a powerful, distributed network of quantum processors. ⚡ The interconnect can send photons at different frequencies, times, and in two propagation directions, enhancing network flexibility and throughput. 📈 Achieved over 60% photon absorption efficiency using a reinforcement learning algorithm. 🪴 This technology could be expanded to other kinds of quantum computers and larger quantum internet systems, essential for scalable quantum networks Read more at https://lnkd.in/efj23u6t Research from Aziza Almanakly , Beatriz Yankelevich, Max Hays, Bharath Kannan, Reouven Assouly, Alex Greene, Michael Gingras, Bethany Niedzielski Huffman, Hannah Stickler, Mollie Schwartz, Kyle Serniak, Joel I-Jan Wang, Terry P. Orlando, Simon Gustavsson, Jeffrey A. Grover, and Will Oliver in the MIT Lincoln Laboratory MIT Department of Physics Massachusetts Institute of Technology