Quantum objects like individual molecules or atoms are typically so small that they require specialized microscopes to observe. However, the quantum structures studied by Elena Redchenko at the Institute for Atomic and Subatomic Physics at TU Wien are large enough to be visible to the naked eye—though only with some effort. Measuring hundreds of micrometers across, these objects are still tiny by everyday standards but are considered immense in the quantum realm.
These large quantum objects are superconducting circuits, which allow electric current to flow without resistance when cooled to low temperatures. Unlike natural atoms, which have fixed properties dictated by nature, these artificial structures can be precisely engineered. This flexibility allows scientists to manipulate and explore various quantum phenomena in a controlled environment. Often called “artificial atoms,” these superconducting circuits can be tailored to suit specific experimental needs.
In a groundbreaking development, researchers have successfully coupled these artificial atoms to create a system capable of storing and retrieving light—an essential advancement for future quantum experiments. This breakthrough was achieved by the research group of Johannes Fink at the Institute of Science and Technology Austria (ISTA), with theoretical contributions from Stefan Rotter at the Institute for Theoretical Physics at TU Wien. Their findings were recently published in Physical Review Letters.
One of the fascinating aspects of quantum physics is that certain objects can only occupy very specific energy levels. As Elena Redchenko, the lead author of the study, explains, “An electron moving around an atomic nucleus can only assume a lower energy state or a higher energy state, but never a state in between. All values in between are simply not physically possible.”
However, with artificial atoms, scientists can customize which energy levels are accessible. “With our artificial atoms, we can choose which energy values should be allowed,” Redchenko continues. “For each artificial atom, we can set exactly how large the distance between the permitted energy values should be.” This customization is what allows researchers to gain unprecedented control over quantum systems.
Microwaves are sent through a special metal wire, or resonator, that runs past the superconducting artificial atoms. These microwaves interact with the artificial atoms, with some microwave radiation transferring back and forth between the wire and the atoms. The strength of this interaction can be finely tuned, giving researchers exceptional control over the quantum system.
One of the most exciting applications of this system is its ability to create precise rhythms of light pulses. By sending a short classical microwave pulse into the wire, the interaction with the artificial atoms generates a series of quantum light pulses, with time intervals that can be controlled. This can be thought of as an on-chip quantum timer. “We can create individual, clearly separated photons, which are crucial for many quantum experiments,” Redchenko explains.
The ability to store photons temporarily is another breakthrough. Researchers can now store photons for a specific period before releasing them again. This capability promises to open up new possibilities in quantum communication and information storage. Redchenko notes, “This technique promises exciting new applications, especially in fields where precise control over light and timing is crucial.”
The work of Redchenko and her colleagues marks a significant step forward in the manipulation of quantum systems. Their system is highly adaptable, and its flexibility opens up a range of new experimental possibilities. From generating and controlling photons to temporarily storing them, these advances pave the way for future quantum technologies that could revolutionize fields such as quantum computing, communications, and sensing.
In the years ahead, artificial atoms like these could play a critical role in the development of quantum networks, where light is used as the medium for transmitting quantum information. By allowing researchers to precisely control the flow and storage of quantum light, this new system could lead to breakthroughs that were previously unimaginable, taking us one step closer to unlocking the full potential of quantum physics.
By Impact Lab
