In the realm of science, crystals are defined as an arrangement of atoms that repeat themselves in space at regular intervals. This means that at every point, the crystal looks exactly the same. However, in 2012, Nobel Prize winner Frank Wilczek raised an intriguing question: Could there be such a thing as a time crystal? Unlike regular crystals that repeat in space, time crystals would repeat themselves in time. This notion sparked much controversy over the years, with some deeming time crystals to be impossible while others attempted to find loopholes to bring them to life under certain special conditions.
Finally, a groundbreaking discovery was made at Tsinghua University in China, with the assistance of TU Wien in Austria. The team managed to successfully create a particularly spectacular type of time crystal using laser light and Rydberg atoms, which have a significantly larger diameter than normal atoms. The results of this experiment were detailed in a publication by the journal Nature Physics.
Unlike the ticking of a clock, which requires external intervention to start and maintain its periodic movement, a time crystal, as per Wilczek’s idea, should exhibit spontaneous periodicity with no physical distinction between different points in time. This concept of spontaneous symmetry breaking is what sets time crystals apart. The tick frequency of a time crystal is predetermined by the system’s physical properties, but the occurrence of the ticks is completely random.
Laser light was directed into a glass container that was filled with a gas of rubidium atoms as part of the experiment conducted at Tsinghua University. The strength of the light signal reaching the other end of the container was monitored. Despite the absence of a specific rhythm imposed on the system, the interactions between the laser light and atoms resulted in the intensity oscillating in highly regular patterns.
The key to the success of the experiment lay in the preparation of the atoms. By transforming the atoms into Rydberg states, where the electrons orbit the nucleus on distinct paths based on their energy levels, the researchers were able to generate a feedback loop by exciting two different Rydberg states simultaneously in each atom. This interplay led to spontaneous oscillations between the atomic states, consequently causing the light absorption to oscillate as well.
The creation of this new system provides a promising platform for delving deeper into the understanding of time crystals, aligning closely with Wilczek’s original concept. The precise and self-sustained oscillations observed in the experiment hold potential for various applications, such as sensors, in the future. This breakthrough could pave the way for innovative advancements in the field of science and technology.
The discovery of a time crystal marks a significant milestone in the scientific community, challenging preconceived notions and pushing the boundaries of what is deemed possible. The meticulous research conducted by the team at Tsinghua University, in collaboration with TU Wien, showcases the power of human innovation and the inherent curiosity that drives groundbreaking discoveries in the world of physics.