(ORDO NEWS) — One way to realize the full potential of quantum computers is to make them the basis of light and matter at the same time: in this way, information can be stored and processed, and also travel at the speed of light.
Scientists have just taken that goal one step further by successfully creating the largest hybrid particles of light and matter ever created.
These quasi-particles, known as Rydberg polaritons, were produced using a piece of stone with copper oxide (Cu2O) crystals from an ancient deposit in Namibia, one of the few places in the world where copper oxide has been found as a gemstone.
A crystal extracted from the rock was polished, thinned to less than a human hair, and placed between two mirrors to capture light, resulting in Rydberg polaritons 100 times larger than any previously observed.
This achievement brings us closer to building a quantum simulator that can run on these Rydberg polaritons, using quantum bits or qubits to store information as 0, 1, and multiple values in between, rather than just 1 and 0 in classical computational bits.
“Creating a quantum simulator with light is the holy grail of science,” says physicist Hamid Ohadi of the University of St. Andrews in the UK.
“We’ve taken a huge leap towards this by creating Rydberg polaritons, a key ingredient.”
A feature of Rydberg polaritons is that they are constantly moving from light to matter and back. The researchers compare light and matter to two sides of the same coin, and it is on the matter side that polaritons can interact with each other.
This is important because light particles move quickly but do not interact with each other. Matter moves more slowly, but it is able to interact. Combining these two abilities could help unlock the potential of quantum computers.
This flexibility is critical to managing quantum states, which remain undefined until they are observed. A fully functioning quantum computer based on this technology is still a long way off, but now we are closer than ever to building such a computer.
Rydberg polaritons are formed as a result of the coupling of excitons and photons. This is where the ancient gem from Namibia lies: Copper oxide is a superconductor, a material that allows electrons to flow without resistance – and previous research has shown it contains giant Rydberg excitons.
Excitons are electrically neutral quasi-particles that, under appropriate conditions, can enter into association with light particles. These large excitons, found in copper oxide, can combine with photons in a special setup known as Fabry-Perot microcavities – essentially a mirror sandwich.
This became a key element in the creation of large Rydberg polaritons.
“Getting the stone on eBay was easy,” says physicist Sai Kiran Rajendran of the University of St. Andrews. “The challenge was to make Rydberg polaritons, which exist in an extremely narrow color range.”
Once fully functional quantum computers can be built—perhaps using these Rydberg polaritons—exponential increases in computing power will allow them to perform complex calculations beyond the capabilities of today’s computers.
As examples, the researchers cite the development of high-temperature superconducting materials and a better understanding of how proteins fold (which could potentially boost our ability to make drugs).
The methods described in the new study need to be improved so that these particles can be used in quantum circuits, but the basics are already there and the team believes their results can be improved in the future.
“These results pave the way for the realization of strongly interacting exciton-polaritons and the study of strongly correlated phases of matter using light on a chip,” the researchers wrote in their paper.
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