US physicists in Wisconsin have built a quantum gate from neutral atoms, rather than ions, claiming it to be a first.
"The current gold standard in experimental quantum computing has been set by trapped ions. People can run small programs now with up to eight ions in traps," said Professor Mark Saffman of the University of Wisconsin-Madison.
A quantum computer will need more entangled structures - quantum bits, also known as qubits - to be useful.
According to the University, an ion-based system presents challenges for scaling up because ions react with each other and their environment making them difficult to control.
"Neutral atoms have the advantage that in their ground state they don't talk to each other, so you can put more of them in a small region without having them interact with each other and cause problems. This is a step forward toward creating larger systems," said Saffman.
The team used lasers, a temperature just above absolute zero, and a vacuum to immobilise two rubidium atoms in optical traps.
Another laser excited the atoms to a high-energy state, entangled them, and created a type of quantum gate called a 'controlled-NOT'.
The Wisconsin group is now working toward arrays of up to 50 atoms.