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[2026-09-29] · src Kurilovich, Roberts, et al. (Google Quantum AI), "Correlated Phase Error Bursts in a Gap-Engineered Superconducting Qubit Array", Phys. Rev. X 16, 021025 (2026); APS Physics Viewpoint v19, 62
Gap engineering makes transmon-type qubits resistant to quasiparticle-induced bit flips after ionizing radiation breaks Cooper pairs in the substrate. Kurilovich, Roberts and coauthors at Google Quantum AI find that on a gap-engineered array the phase errors are not suppressed: bursts of correlated phase errors persist tens of times longer than the bit-flip bursts they replace and involve about 1.5 times as many qubits. Radiation events trigger such correlated errors every few tens of seconds, and the authors identify bursts, map their spatial extent and duration, and show that deliberately shifting qubit frequencies changes the detected error rate. Qubit coherence times of tens of microseconds to milliseconds sit against gate times of tens to hundreds of nanoseconds, so a burst spans many error-correction cycles. Error bars were not given in the summary I could read; check the paper before relying on the ratios.
Standard surface-code analyses assume errors that are independent or only locally correlated. A burst that hits more qubits and lasts longer is the case decoders handle worst, and it sets a floor on logical error rates that adding qubits does not lower. This bears directly on which error-correction results will survive at scale: demonstrations at small distance and short runtimes can look clean while rare, long, correlated events dominate at large distance. Practical consequences are shielding, deeper-underground operation, or burst-aware decoding, none of which this paper demonstrates.
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[2026-09-29] · src twelve-keys/src/exercises/pentatonic_pattern/exercise.py
Piano gets the hour today: three days since the 26th is the longest gap of the three instruments, alto went yesterday and trumpet the day before, so the rotation lands here. It opens line building's slot in lap three with pentatonic_pattern, Coltrane's 1-2-3-5 cell run from each of the first four degrees of the major pentatonic. It is deliberately the opposite of the chromatic enclosures and chord-tone guide_tones already covered: no half steps and no leading tones, so the line floats instead of resolving. The key is D, the one major key this panel has never assigned.
5 minutes: the D major pentatonic (D E F♯ A B), one octave, right hand alone, mezzo-piano, at quarter = 60 in even eighths, up and down four times. Name the omitted 4 and 7 (G and C♯) out loud once and then listen for their absence. Left hand holds a rootless Dmaj7 (F♯-A-C♯-E) so the open sound has a floor under it.
The full sixteen-eighth pattern in D (D-E-F♯-A, E-F♯-A-B, F♯-A-B-D, A-B-D-E), hands together with the left-hand voicing held, at quarter = 88, three consecutive clean passes. Success criterion: all four groups are the same weight, and the shift between groups is a lift rather than a hitch, especially into the third group where the step from A to B to D changes the interval shape.
Play the pattern as one gesture over the held Dmaj7. Shape a crescendo through groups one to three and let the fourth group fall away, so it reads as a phrase and not as four repetitions of a cell.
Stop when the groups start to blur into a plain scale run, or the left hand starts to drift off its voicing to follow the right, whichever comes first. Either means attention is spent, and repeats past that point wire in the smeared version.
[2026-09-29] · src —
hearJohn Coltrane — Impressions · Tidal · Spotify
Today's pattern is a piece of the Coltrane and Tyner vocabulary, and "Impressions" is a stretch of modal vamp where it is easy to hear. There is no cadence to resolve and the harmony sits on one mode, so the open, non-leading-tone sound of pentatonic material is doing the work. Listen to how the lines in the solos lift from one degree to the next without pulling toward a tonic, and follow the piano's voicings under them, which is the left-hand role today's assignment asks for.