Coulomb blockade in microscopic material defects as a source of decoherence and noise in solid-state quantum circuits
Tiny metal specs in quantum chips cause unexpected noise and signal loss
Researchers discovered that microscopic metallic grains embedded in quantum computer materials are a major source of signal degradation, matching the impact of the previously identified culprit known as two-level system defects. These grains are created during standard manufacturing and had been overlooked because existing diagnostic tools misidentified their damage as coming from other sources.
Quantum computers lose their computational power when their delicate quantum states decay—a process called decoherence. Scientists have spent years trying to eliminate the known sources of this decay, but progress has stalled because they were chasing the wrong problem. By identifying metallic grains as a major culprit, manufacturers now have a concrete target: changing fabrication processes to prevent these grains from forming in the first place, which could significantly extend how long quantum states survive and improve device performance.