Dissipative phase transitions (DPTs) in open quantum systems occur due to the interplay between unitary evolution, external forces, and energy loss. While second-order DPTs have primarily been explored through theoretical studies, first-order DPTs have been experimentally observed in single-photon-driven Kerr resonators.
EPFL’s new study explores first- and second-order DPTs using both experiments and theory. The researchers built a superconducting Kerr resonator, a special device designed to precisely control quantum properties.
They introduced a two-photon drive into the system, sending pairs of photons to manipulate its quantum state precisely. This setup helped them see how the system changes between different quantum phases, giving a better understanding of how it behaves in controlled settings.
Researchers then systematically changed parameters like detuning and drive amplitude to determine the system’s transitions from one quantum state to another. This allowed them to observe both a first-order and second-order DPT.
For enhanced precision, researchers conducted the experiments at temperatures near absolute zero, reducing background noise to almost nothing.
The Kerr resonator played a crucial role in the study, magnifying delicate quantum effects that are typically too subtle to detect. Its exceptional sensitivity to two-photon signals allowed the researchers to delve into phase transitions with unmatched precision.
Thanks to this, the research team was able to control the photon behavior of the photons emitted by the resonator with ultra-sensitive detectors. Later, the team used advanced mathematical techniques, such as connecting with the spectral properties of the Liouvillian superoperator, to track and analyze the system’s phase transitions precisely.
A phenomenon called squeezing was observed for the second-order DPT. In this phenomenon, quantum fluctuations drop to levels lower than the natural background noise of space. It indicates that the system is in a highly sensitive and transformative state.
On the other hand, distinct hysteresis cycles were observed in the first-order DPT. In this phenomenon, the system exists in two states depending on how parameters were tuned.
The researchers observed metastable states during the first-order DPT, where the system stayed in one stable state before suddenly shifting to another. This behavior, called hysteresis, reflects the competition between different phases.
They also noted “critical slowing down” in both transitions, where the system’s response slowed significantly near critical points. This matched theoretical predictions based on Liouvillian theory, confirming its accuracy. Such slowing down is a universal feature of phase transitions and could be used for more precise quantum measurements.
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Researchers noted, “Exploring dissipative phase transitions (DPTs) unlocks exciting opportunities to design quantum systems that are not only stable but highly adaptable. This advancement can transform quantum information technologies, enabling more reliable error correction in quantum computing and paving the way for ultra-sensitive quantum sensors.”
“Beyond its technical impact, this work highlights the immense value of interdisciplinary collaboration. By combining experimental physics, sophisticated theoretical frameworks, and innovative engineering, researchers are pushing the boundaries of science, bridging disciplines to tackle complex challenges and uncover new possibilities.”
Guillaume Beaulieu, the paper’s first author, said, “In fact, a very interesting aspect of this work is that it also demonstrates how close collaboration between theory and experiment can lead to results far greater than what either group could have achieved independently.”
Journal Reference
- Guillaume Beaulieu, Fabrizio Minganti, Simone Frasca, Vincenzo Savona, Simone Felicetti, Roberto Di Candia, Pasquale Scarlino. Observation of first- and second-order dissipative phase transitions in a two-photon driven Kerr resonator. Nature Communications 10 March 2025. DOI: 10.1038/s41467-025-56830-w
Source: Tech Explorist
