Disclosed herein are quantum dot devices, as well as related computing devices and methods. For example, in some embodiments, a quantum dot device may include: a quantum well stack; a first gate and an adjacent second gate above the quantum well stack; and a multi-spacer between the first gate and the second gate, wherein the multi-spacer includes a first spacer and a second spacer different from the first spacer, and the first spacer is at least partially between the quantum well stack and the second spacer.