Researchers from the University of Innsbruck have successfully created hot Schrödinger cat states in a superconducting microwave resonator, defying the long-held assumption that quantum effects are destroyed by higher temperatures. The study, published in Science Advances, shows that it is possible to observe and use quantum phenomena even in less perfect, warmer conditions.
Schrödinger cat states are a fundamental concept in quantum physics, where a quantum object exists simultaneously in two different states. In the past, these states were only created by cooling the quantum object to its ground state. However, the researchers, led by Gerhard Kirchmair and Oriol Romero-Isart, have demonstrated for the first time that it is possible to create quantum superpositions from thermally excited states.
The team used a transmon qubit in a microwave resonator to generate the cat states, achieving temperatures of up to 1.8 Kelvin – 60 times hotter than the ambient temperature in the cavity. They employed two special protocols to create the hot Schrödinger cat states, which were previously used to produce cat states starting from the ground state.
The results show that it is possible to generate highly mixed quantum states with distinct quantum properties, even at high temperatures. This opens up new opportunities for the creation and use of quantum superpositions in nanomechanical oscillators, where achieving the ground state can be technically challenging.
The research findings suggest that if a system’s interactions are created correctly, temperature ultimately doesn’t matter. The discovery could benefit the development of quantum technologies and reveal new possibilities for observing and using quantum phenomena.
Source: https://phys.org/news/2025-04-hot-schrdinger-cat-states.html