Physicists make “unprecedented” qubit breakthrough in the race to build quantum computers
It may seem as if we’ve been on the cusp of affordable, super-powerful and widespread quantum computers for some time, but this latest breakthrough could finally be the turning point.
Two papers, published in the journal Nature, detail how researchers created quantum simulators consisting of an unprecedented 53 qubits. Up till now, such simulators were only capable of running and controlling around two dozen qubits.
Quantum simulators are a form of quantum computer that simulate how quantum particles interact with each other. By understanding these complex interactions, computer scientists and physicists can build more effective, more powerful and ultimately more useful quantum computers.
Relatively small numbers of individually controlled qubits have already been used to simulate systems such as molecules, however, scaling this up to larger groups of quantum elements — and thus simulating more complex quantum systems — has been a challenge.
In computing, information is stored in ‘bits’ in either the state 1 or 0, like a light switch turned on or off. By contrast, qubits are the backbone of a quantum computer and the unit of information can be 1 or 0, or a superposition of the two states. Given their complexity, qubits are much harder to make and, once made, they’re much harder to get them to keep hold of information, and control how they believe.
Researchers have tried using superconducting materials, ions held in ion traps or individual neutral atoms, as well as molecules of varying complexity to build them.
As part of the recent research, teams from the University of Maryland and National Institute of Standards and Technology made the qubits from ytterbium ions, strung together in rows like pearls.
Mikhail Lukin and his team at Harvard used 51 so-called Rydberg atoms, while Christopher Monroe and his colleagues from Maryland trapped ions to study phase transitions in Ising-type quantum magnets.
In this quantum simulator, the qubits were cooled in a vacuum by lasers being fired towards them causing them to interact between particles. Each ion was manipulated and had the same electrical charge meaning they repelled each other, like magnets. This is known as quantum magnetism. An electric field was then used to force the repelled ions into neat rows.
At such levels, these quantum computers are capable of modelling physic interactions that are too complicated for even supercomputers.