A groundbreaking experiment has directly observed Dissipative Phase Transitions (DPTs) in quantum systems, revealing how quantum states shift under controlled conditions. This discovery could significantly enhance quantum computers and sensors by making them more stable and precise.
Unlike familiar phase transitions in classical physics (like water freezing), quantum phase transitions follow different rules governed by principles such as Heisenberg’s uncertainty. When quantum systems lose energy to their surroundings —a process called dissipation— they can be driven into new states, creating DPTs.
These transitions come in different types: first-order DPTs involve abrupt jumps between states, while second-order DPTs produce more gradual but still significant changes to fundamental system properties like symmetry.
Understanding DPTs is essential for studying quantum systems outside thermal equilibrium and has practical applications in quantum technology. Second-order DPTs could improve quantum information storage, while first-order DPTs provide insights into system stability and control.
The breakthrough came from Professor Pasquale Scarlino‘s team at EPFL, who used a superconducting Kerr resonator —a highly tunable quantum device— to observe these transitions. By introducing a two-photon drive and working at near-absolute zero temperatures, they precisely controlled and monitored quantum states, successfully observing both first-order and second-order DPTs.
Their key findings included “squeezing” during the second-order DPT, where quantum fluctuations drop below natural background noise; metastable states and hysteresis cycles during the first-order DPT, where the system’s state depends on its history; and “critical slowing down” near transition points, confirming theoretical predictions.
This research opens new possibilities for creating quantum systems that are both stable and responsive, potentially revolutionizing quantum information technologies like error correction in quantum computing and ultra-sensitive quantum sensor development. As Guillaume Beaulieu, the paper’s first author, noted, the project demonstrated how collaboration between theory and experiment can achieve results greater than either approach could accomplish independently.
Reference: “Observation of first- and second-order dissipative phase transitions in a two-photon driven Kerr resonator” by Guillaume Beaulieu, Fabrizio Minganti, Simone Frasca, Vincenzo Savona, Simone Felicetti, Roberto Di Candia and Pasquale Scarlino, 10 March 2025, Nature Communications. DOI: 10.1038/s41467-025-56830-w
