QUEZON CITY, Philippines (Jul 2025) — A team of physicists led by Dr. Jayson Cosme of the University of the Philippines has achieved a milestone in quantum research: the first experimental observation of the “birth of a torus” in a quantum system.
Using lasers, mirrors, and a unique setup involving time crystals, the team demonstrated how a simple oscillating system could transition into a more complex state — from a loop into a donut-shaped form, or torus, in phase space. This kind of transition has long been seen in classical systems but had only been theorized in the quantum realm.
Time crystals are ultra-cold atoms that periodically switch between two states, similar to the rhythm of a heartbeat. Their behavior can be visualized in phase space — a kind of mathematical map — where a stable system appears as a loop. But when the dynamics grow more complex, this loop can transform into a torus.
Dr. Cosme, a physicist at UP Diliman’s National Institute of Physics, first made headlines in 2022 when he and collaborators in Germany showed that time crystals could be formed even without a pulsating laser. Instead, they used a continuous laser and mirrors to trap and intensify the light, prompting rubidium atoms to oscillate spontaneously.
In this latest breakthrough, the researchers increased the laser’s intensity and found that the time crystal’s behavior changed again. The system became unstable and its trajectory in phase space transformed into a torus. This marks the first time the elusive phenomenon — the “birth of a torus” — has been observed in a quantum system.
“The light’s intensity acts like a switch,” said Dr. Cosme. “Below a certain level, the system stays in a loop. But push it past the threshold, and it transforms into a torus.”
The transition was difficult to detect due to the extreme sensitivity of quantum systems to light. But the team’s experimental setup, which uses ultra-precise control of atoms and photons, made the observation possible. Their findings are now published in the journal Physical Review Letters.
More than just a theoretical curiosity, this discovery has potential applications. Systems that operate near the loop-to-torus transition point could be used to create highly sensitive detectors for light or electromagnetic fields.
Looking ahead, Dr. Cosme and his collaborators are exploring whether such quantum transitions can be predicted before they happen — a question with implications for quantum sensing and computing. They are also using the same setup to study other quantum phenomena, including the Kibble-Zurek mechanism, which relates to how systems behave during rapid changes.
Filipino researchers continue to play a key role in global quantum science, pushing boundaries and placing the Philippines on the map of cutting-edge discovery.
For more updates on this and other research, visit the UP National Institute of Physics or follow their latest publications online.
