Curator's Take
This research tackles one of quantum computing's most pressing infrastructure challenges: how to connect multiple quantum processors over meaningful distances without destroying the delicate quantum states that make them useful. The team's demonstration of a 30-meter cryogenic link between superconducting quantum devices represents a crucial step toward distributed quantum networks, where quantum computers could work together to solve problems too large for any single machine. What makes this particularly significant is that they maintained the ultra-low temperatures (below 50 mK) required for superconducting qubits to function across the entire 30-meter span, essentially creating the quantum equivalent of a LAN cable that preserves quantum entanglement. This breakthrough opens the door to quantum computing clusters and eventually quantum internet infrastructure, where quantum advantages could be shared across physically separated locations.
— Mark Eatherly
Summary
Quantum technologies promise a radically new way to solve classically intractable computing problems. Superconducting circuits as a platform are at the forefront of this field. The cryogenic operation temperatures of superconducting circuits however impose challenges for the further scaling to many connected quantum information processing units into a local area or global network. In this work, we present a hardware solution for connecting quantum devices operating at microwave frequencies into local area networks, which enable the exchange of quantum information between spatially separated parties. Specifically, we demonstrate a modular system spanning distances of 5, 10 and 30 meters operated at cryogenic temperatures and connecting two superconducting circuit systems, located in individual dilution refrigerators, through a quantum communication channel. We develop a thermal model to evaluate the heat transfer processes in the setup, optimize the design and select appropriate materials for its construction. The assembled 30-meter-long system achieves operating temperatures of below 50 mK after a cooldown time of about six and a half days. This link enables the execution of distributed quantum computing and communication algorithms. It also adds the resource of non-locality, certified by a loophole-free Bell test, to the field of quantum science and technology with superconducting circuits.