Physicists from the University of Chicago have created a “quantum flute” that, like the Pied Piper, can coax light particles to move together in a never-before-seen manner. The breakthrough, which was described in two studies published in Physical Review Letters and Nature Physics, could pave the way for the development of new forms of error correction and quantum memories in quantum computers, as well as the observation of quantum phenomena that cannot be observed in nature.
The lab of associate professor David Schuster focuses on quantum bits, the quantum counterpart of a computer bit, which utilize the peculiar properties of subatomic and atomic particles to do otherwise impossible tasks. In this experiment, photons, also known as light particles, were utilized in the microwave range. They came up with a device that is made up of a solid block of metal that has a sizable cavity cut out of it and is intended to capture photons using microwave frequencies. The cavity is made by drilling offset holes, similar to flute holes.
According to Schuster, “much like in a musical instrument,” it is possible to transport a single or several wavelengths of photons throughout the entire structure. Each wavelength produces a ‘note’ that can be used to encode quantum information. The researchers can then control the interactions of the “notes” using a superconducting electrical circuit containing a master quantum bit.
The most peculiar discovery, however, was the collective behavior of photons. Photons rarely interact in nature; they just flow through one another. Scientists can sometimes induce two photons to react to each other’s presence through meticulous preparation.
“Here we do something even weirder,” Schuster stated. “Initially, the photons do not interact with one another, but when the overall energy in the system hits a tipping point, they all start chatting to one another.”
Observing that many photons “talking” to one another in a laboratory experiment is as bizarre as witnessing a cat walk on its hind legs.
According to Schuster’s explanation, “the majority of particle interactions are typically one-on-one,” with 2 particles rebounding off of or attracting one other. “Typically, when you add a third, they continue to interact sequentially with one or the other. However, this system has them all interacting simultaneously.”
Their research only examined up to five “notes” at a time, but the scientists can envision potentially controlling hundreds or thousands of notes with a single qubit. With a system as complex as a quantum computer, engineers strive to simplify wherever possible. Schuster stated, “If you wanted to construct a quantum computer with 1,000 bits and could control them all with a single bit, that would be tremendously valuable.”
Additionally, the researchers are enthusiastic about the behavior itself. These interactions have never been observed in nature, therefore the researchers believe that the discovery can be used to simulate complex scientific events that cannot even be observed on Earth, such as the physics of black holes.
Beyond this, the experiments are simply enjoyable.
“Typically, quantum interactions occur on length and temporal scales that are too small or quick to observe. In our technology, we can monitor individual photons in any of our notes and observe the interaction in real time. It is quite fascinating to’see’ a quantum interaction with the naked eye “Srivatsan Chakram, a postdoctoral researcher at the University of Chicago and now an assistant professor at Rutgers University, is the co-first author of the paper.