# Quantum Qubits: Lasers Used to Create One of the Largest Quantum Computer Simulations Ever

Experts have successfully manipulated individual atoms with a cutting-edge laser technique.

Physicists from Harvard University and the Massachusetts Institute of Technology used lasers to trap and move 51 quantum bits—individual atoms, also known as qubits—for the first time ever. Their technology could help make superfast quantum computers a working reality.

By changing the way the atoms interact with one another, scientists can simulate new states of matter or find the best way to solve optimization problems. Traditional computers struggle to find, for example, the best answer to the traveling-salesman problem: If a salesman has lots of places to visit, what is the quickest route?

"This problem is exponentially hard for a classical computer, meaning it could solve this for a certain number of cities, but if I wanted to add more cities, it would get much harder, very quickly," said study co-author and professor at MIT Vladan Vuletic in a press release.

The team's technology mimics the workings of a quantum computer—ultra-powerful machines that are largely the stuff of theory. Their work is published in *Nature*.

Traditional computers work with "bits." These binary "ones" and "zeros" process data much more slowly than a quantum computer could. Qubits can exist in both the "one" and "zero" position, allowing each qubit to process two lines of computation. This creates incredibly powerful machines that could revolutionize technology. Such devices could make factory machines run faster, make airplanes safer and even improve the way we sequence DNA. Quantum encryption is currently safeguarding digital secrets in China.

By changing the way qubits are arranged, the researchers can simulate different problems. If they turn up the frequency or change the color of their laser beams, the scientists can find more and more solutions. The more qubits involved, the more problems can be simulated. "We think we can scale it up to a few hundred," Vuletic said.

For now, however, the team plans to test the 51-qubit system with more optimization problems.

"It is not just about qubits, the fundamental building blocks for quantum machines. Building a large-scale quantum computer will also need a revolution in classical computing and device engineering," said David Reilly, a professor at the University of Sydney, whose paper in *Nature Communications* yesterday brought the machines one step closer to reality.

"Even if we had millions of qubits today, it is not clear that we have the classical technology to control them. Realizing a scaled-up quantum computer will require the invention of new devices and techniques at the quantum-classical interface."