At a Glance
- Researchers from Innsbruck, Austria, demonstrated that quantum effects, like Schrödinger cat states, can be observed at temperatures up to 1.8 kelvin, a significant breakthrough in quantum physics.
- Schrödinger cat states, where an object exists in two states simultaneously, usually require extremely low temperatures, but the new study shows that quantum superpositions can occur even in warmer conditions.
- The researchers used a transmon qubit inside a microwave resonator to generate these hot Schrödinger cat states, achieving quantum superpositions at higher temperatures with two specially adapted protocols.
- This study challenges the belief that temperature disrupts quantum effects, suggesting that quantum phenomena can persist at higher temperatures, which could lead to new quantum technologies.
- By proving that quantum interference is possible in less-than-ideal conditions, the research opens new possibilities for quantum computing and other technologies, making temperature less of a limiting factor for future advancements.
Quantum states are typically delicate and can only be observed under highly controlled conditions, often requiring extremely low temperatures. However, researchers from Innsbruck, Austria, have demonstrated that quantum effects can be observed even under warmer conditions, marking a significant breakthrough in quantum physics. Their study, published in Science Advances, shows that it is possible to create quantum superpositions from thermally excited states, or “hot” Schrödinger cat states, at temperatures up to 1.8 kelvin—far warmer than the conditions required for quantum experiments.
Schrödinger cat states are a unique phenomenon in quantum physics where an object can exist simultaneously, such as being both alive and dead, as per Schrödinger’s famous thought experiment. These superposition states have been seen in previous experiments, but they typically require cooling the system to its lowest energy state, known as the ground state. The new research, led by Gerhard Kirchmair and Oriol Romero-Isart, shows that it is possible to create these quantum superpositions even without starting from the coldest state, which had been assumed necessary for such phenomena.
The team used a transmon qubit, a type of quantum bit, inside a microwave resonator to generate these hot Schrödinger cat states. By carefully controlling the interactions between the qubit and the resonator, the researchers created quantum superpositions at temperatures much higher than previously thought possible. This was achieved using two specially adapted protocols that had previously successfully created cat states from the ground state. These results open up new possibilities for creating quantum states in systems that are difficult to cool to extremely low temperatures, such as nanomechanical oscillators.
The findings of this study challenge the conventional wisdom that temperature disrupts quantum effects. As Thomas Agrenius, one of the researchers, points out, the ability to create and measure quantum superpositions at higher temperatures could pave the way for new quantum technologies. By proving that quantum interference can persist even in less-than-ideal conditions, this work suggests that temperature is not a limiting factor for quantum phenomena, offering new opportunities for future advancements in quantum computing and other technologies.
References
- Yang, I., Agrenius, T., Usova, V., Romero-Isart, O., & Kirchmair, G. (2025). Hot Schrödinger cat states. Science Advances, 11(14), eadr4492. https://doi.org/10.1126/sciadv.adr4492
- University of Innsbruck. (2025, April 4). Hot Schrödinger cat states created. Phys.Org; University of Innsbruck. https://phys.org/news/2025-04-hot-schrdinger-cat-states.html
