A quantum dot is a tiny trap that holds a single charge. If there's a sharp ledge next to the trap, charge piles up on it and creates interference. Engineers replaced the ledge with a smooth ramp, and the trap started running quieter.
In a material made of silicon and germanium, there used to be a sharp transition between the layers. Charge accumulated at that transition, like dust on a step. Each speck of dust changed the electric field, and the quantum dot twitched.
Measurements showed that the charge noise became the lowest among germanium quantum dots on silicon. The transition between the states with zero and one hole didn't drift for almost two hours. This means quantum dots will be able to store information longer, and quantum computers will become more reliable.
The charge noise in these devices is so low that the transition voltage between the zero-hole and one-hole states does not change for nearly two hours, even though such transitions usually drift within minutes.