A quantum computer is like an orchestra where each qubit is a musician, and a measurement is the conductor's attempt to hear who played what. But the hall is noisy: the signal fades like sound through a thick wall, and the conductor himself sometimes mixes up the notes. Physicists measured this noise with precision down to each individual disturbance.
They took a superconducting qubit, a tiny circuit that behaves like an atom, and performed a series of measurements in the middle of a computation. Such measurements are needed for error correction: the computer checks itself as it works. But each measurement itself introduces an error. To see it, the scientists used a method that decomposes the error into elementary parts: signal decay, readout inaccuracy, and incomplete "collapse" of the qubit into a definite state.
It turned out that the strength of errors changes with the amplitude of the measurement pulse, like the volume of a voice in a noisy room. When the pulse is weak, errors grow; when it is strong, they fall, but not to zero. The physicists built a simple model with a few parameters that predicts these changes. Now measurements can be tuned to reduce errors.
Such error decomposition is like tuning instruments before a concert. If you can hear that the violin is out of tune because of a loose string, not because of poor acoustics, you can fix just the string. For quantum computers, this is a step toward computing without glitches.
Superconducting qubits operate at temperatures lower than in outer space — about 0.01 degrees above absolute zero.