Yes—microscopic defects in interfaces, oxides, tunnel barriers, and film edges can absorb energy or fluctuate, producing different relaxation and dephasing even in nominally identical transmons. Recent materials-level work links coherence spread to nanoscale fabrication variations, but the evidence also points to quasiparticles and environmental mechanisms, so defects are a major contributor rather than a universal explanation.
Two lenses on the same evidence. Source weight and the primary source ratio show what each rests on.
Alternative
Source weight 33%
A narrower defect-centered explanation may overstate how much of the observed spread is intrinsic to materials. Coherence is a combined outcome of microscopic defects, nonequilibrium quasiparticles, radiation, adsorbates, magnetic flux noise, packaging, and measurement conditions. Some surface interventions improve flux noise without materially changing relaxation or echo decay, showing that not every material change controls every coherence metric.
Quasiparticles, stray infrared radiation, and slotline modes have been identified as important decoherence mechanisms alongside material defects.
Surface treatments can improve flux-noise parameters while leaving relaxation and echo decay largely unchanged at the sweet spot.
A lifetime-statistics study explicitly separates the effects of quasiparticles and two-level systems, indicating that both mechanisms can shape measured lifetime variation.
Observed defect correlations support a microscopic contribution, but they do not show that defects explain all device-to-device coherence differences.