Seven technologies to watch in 2022

https://www.nature.com/articles/d41586-022-00163-x

Quantum simulation (Michael Eisenstein, Nature, 2022)

Atoms are, well, atomic in size. But under the right conditions, they can be coaxed into a highly-excited, super-sized state with diameters on the order of one micrometre or more. By performing this excitation on carefully positioned arrays of hundreds of atoms in a controlled fashion, physicists have demonstrated that they can solve challenging physics problems that push conventional computers to their limits.

Quantum computers manage data in the form of qubits. Coupled together using the quantum physics phenomenon called entanglement, qubits can influence each other at a distance. These qubits can drastically increase the computing power that can be achieved with a given allotment of qubits relative to an equivalent number of bits in a classical computer.

Several groups have successfully used individual ions as qubits, but their electrical charges make them challenging to assemble at high density. Physicists including Antoine Browaeys at the French national research agency CNRS in Paris and Mikhail Lukin at Harvard University in Cambridge, Massachusetts, are exploring an alternative approach. The teams use optical tweezers to precisely position uncharged atoms in tightly packed 2D and 3D arrays, then apply lasers to excite these particles into large-diameter ‘Rydberg atoms’ that become entangled with their neighbours. “Rydberg atom systems are individually controllable, and their interactions can be turned on and off,” explains physicist Jaewook Ahn at the Korea Advanced Institute of Science and Technology in Daejeon, South Korea. This in turn confers programmability.

This approach has gained considerable momentum in the span of just a few years, with technological advances that have improved the stability and performance of Rydberg atom arrays, as well as rapid scaling from a few dozen qubits to several hundred. Early applications have focused on defined problems, such as predicting properties of materials, but the approach is versatile. “So far, any theoretical model that the theorists came up with, there was a way to implement it,” Browaeys says.

Pioneers in the field have founded companies that are developing Rydberg atom array-based systems for laboratory use, and Browaeys estimates that such quantum simulators could be commercially available in a year or two. But this work could also pave the way towards quantum computers that can be applied more generally, including in economics, logistics and encryption. Researchers are still struggling to define this still-nascent technology’s place in the computing world, but Ahn draws parallels to the Wright brothers’ early push into aviation. “That first airplane didn’t have any transportation advantages,” says Ahn, “but it eventually changed the world.”