A quantum computer isn't a monolith: it's more like an orchestra, where each qubit must play its part without drowning out the neighbors. In ion-based machines, two types of qubits are used: some store information, others process it. Previously, each type required its own laser, like separate batons for violins and trumpets.
Physicists have now proposed using just one baton. They used a pulsed laser that, instead of a single pure note, produces a whole comb of frequencies, like a comb with many teeth. Two teeth of this comb happened to resonate with the two types of qubits in an ytterbium-171 ion. One laser made both types of qubits work: both storing and computing.
They also tested the connection between qubits: the laser successfully entangled two qubits of different types — a basic operation for any quantum computation. Previously, this would have required two lasers and complex synchronization. Now, a single device does it all.
It's like having one remote control for both the TV and the air conditioner, whereas before each had its own. The quantum computer's design becomes simpler; fewer parts mean fewer chances of failure. The road to practical quantum machines gets a little smoother.
An ytterbium-171 ion in a trap hangs in vacuum, held by electric fields. A single such ion can be laser-cooled to thousandths of a kelvin — colder than outer space.