A quantum leap for computing: lasers add dexterity and speed

The first re-programmable quantum computer is powered by five ytterbium atoms, and researchers say it is capable of running any algorithm.

S. Debnath and E. Edwards/JQI
Close-up photo of an ion trap.

Is the quantum age finally upon us?

The first ever re-programmable quantum computer was described in the journal Nature on Wednesday. Researchers say their device, which is powered by five ytterbium atoms, is capable of running any algorithm. The study has been hailed as a breakthrough, paving the way for general-purpose quantum computers.

The basic unit of information in computing is called a bit. These binary digits – 0 or 1, on or off – allow conventional computers to perform tasks. But this system can be limiting, and some more complex calculations and encryptions can take years to solve.

That’s where quantum computing comes in. Quantum computers utilizes the qubit, or quantum bit, rather than the standard bit. Qubits in “superposition” can exist in both binary states simultaneously. As a result, these devices can solve complex calculations in a fraction of the time it would take a conventional computer.

In the last decade, researchers have produced a number of small, functional quantum computers. But scalability has been a major issue. Quantum systems are extremely difficult to mass produce, and most are only capable of performing a specific algorithm.

But a new quantum computer, developed at the University of Maryland’s Joint Quantum Institute, could change all that. Researchers used five ytterbium atoms as qubits to power their device. The atoms, which become charged ions when stripped of an electron, are held in place by a magnetic “ion trap.” Using lasers, researchers could manipulate the ions and influence their interactions with each other.

“By reducing an algorithm into a series of laser pulses that push on the appropriate ions, we can reconfigure the wiring between these qubits from the outside,” lead author Shantanu Debnath said in a statement. “It becomes a software problem, and no other quantum computing architecture has this flexibility.”

In March, scientists produced a similar computer that was capable of solving basic factoring problems, The Christian Science Monitor reported. But new quantum devices have moved beyond simple arithmetic. 

Debnath and colleagues tested the module on three algorithms, including the Quantum Fourier Transform (QFT), which is considered among the most complex quantum algorithms. The computer ran the QFT with a 70 percent success rate. The other two algorithms ran successfully more than 90 percent of the time.

Researchers called their device a quantum module, because it could potentially integrate with identical modules to power a more complex computer. In future tests, the team plans to run new algorithms with a system of more than five qubits.

"We'd like this system to serve as a test bed for examining the challenges of multiqubit operations, and find ways to make them better," Debnath told Live Science.

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