1
[2026-09-13] · src Hadjri, Yue, Han, et al. (Ju and Stern groups, MIT/Weizmann); arXiv:2609.09422 (2026-09-08)
Rhombohedral pentalayer graphene on hBN hosts the fractional quantum anomalous Hall effect (FQAHE) at zero magnetic field, but whether the transitions between its various field-tuned phases - Fermi liquid, fractional Chern insulator (FCI), extended quantum anomalous Hall, correlated insulator - follow the same "two-phase" microscopic picture established for ordinary Landau-level quantum Hall transitions has been untested, because that picture was previously only ever probed by sweeping a magnetic field in GaAs two-dimensional electron gases, not by sweeping a displacement field in a Chern band. Having improved device filtering and grounding to cut residual resistance to hundreds of ohms - about 15 times lower than the same device's original 2024 FQAHE discovery run - the authors resolved 11 distinct fractional states and swept the displacement field D through each transition while tracking longitudinal and Hall resistivity (and conductivity). The FL-FCI and FL-EQAH-FCI transitions trace the semicircle relations in the resistivity plane that the two-phase model predicts - the first experimental evidence of that microscopic picture under D-field rather than B-field tuning. The FCI-to-insulator transition, however, only traces a semicircle in conductivity, not resistivity, with the Hall resistivity staying pinned near its quantized FCI value (7h/3e2 at filling 3/7) even as the longitudinal resistivity diverges - the signature of a "fractional quantized anomalous Hall insulator," a zero-field, fractional-filling analog of the quantized Hall insulator known from conventional 2DEGs. Comparing the temperature dependence of resistance in the three most robust FCI states to a thermal-activation model, the authors extract transport gaps reaching about 0.25 meV (~3 K), following the same "V-shape" versus distance from half-filling that composite-fermion theory predicts for ordinary fractional quantum Hall states, and comparable in size to FQH gaps in GaAs devices though smaller than in bilayer graphene at similar density - which the authors attribute to pentalayer graphene's higher self-screening.
The zoo of FQAHE-related phases in moire graphene has grown fast since 2023 with comparatively little transport evidence for how they actually connect to each other; this paper supplies that evidence rather than another phase. It establishes, quantitatively, that the flat Chern band in this system behaves like a genuine analog of a Landau level - not just in hosting fractional states, but in obeying the same two-phase transport law and the same composite-fermion gap systematics - and it identifies a distinct insulating phase (the fractional quantized anomalous Hall insulator) that has no magnetic-field-tuned counterpart described in the literature until now. The practical payoff the authors point to is a cleaner path toward gate-defined junctions and anyon interferometry in these devices, where knowing precisely which phase occupies which region of the displacement-field diagram, and how sharply the boundary between them is set, is a prerequisite rather than an afterthought.
2
[2026-09-13] · src —
Alto takes today's slot — three days since its last session is the longest gap of the three instruments right now, and trumpet went yesterday, so the two chops-dependent instruments don't land back to back. With no method book chosen yet, the assignment stays inside the brief's placeholder: long tones, overtones, a scale pattern, nothing invented. Today's fundamental is low A♭, continuing the upward semitone climb the survey has held since it passed E♭, and both the warmup shape and the musical-target pattern close out their own second circuit — a crescendo attack after last time's taper, and the widest interval skip a single octave has room left for.
5 minutes: long tones on low A♭ and A, starting at pp and building a steady, controlled crescendo to f over eight counts, quarter=60, eight full counts per note. The target is a rise that stays centered in pitch the whole way up rather than sharpening as the air pressure builds — the same demand last tested on 09-01, two fundamentals back down the climb.
Overtone series from fundamental low A♭: voice up through A♭–A♭–E♭–A♭–C using only the low A♭ fingering, changing partials with throat and voicing, not embouchure — the same method as every prior session, now a tenth semitone higher than where the climb started. Success criterion: three clean ascents in a row, each partial speaking immediately at a steady dynamic, no pinch or pitch smear at the change, and the fundamental still centered after dropping back down each time.
A♭ major scale, one octave, in broken sevenths (1-7-2-8) rather than the thirds, fourths, fifths or sixths this survey has already broken up — with only one octave to work in, a seventh only leaves room for two pairs before the pattern runs out of scale, the shortest cycle this progression has had and the widest skip it has room for. Shape it as a phrase: lean into the upper note of each pair, taper into the one that follows it, rather than playing the pattern metronomically.
Stop the moment the crescendo starts sharpening instead of staying centered on the way up, or an overtone needs a jaw shove or throat squeeze to speak — both are fatigue standing in for support, and reps past that point train the substitute instead of the real thing.
[2026-09-13] · src —
hearEric Dolphy — Out to Lunch (Out to Lunch!) · Tidal · Spotify
Dolphy splits his horns across this record — the title track is one of only two where he plays alto rather than bass clarinet or flute — and its melody is built on exactly the kind of skip today's musical target is chasing: angular leaps that jump past where a stepwise line would go next, so the ear has to track where the phrase actually landed rather than where it seemed to be heading. Listen for how a line that looks disjointed on paper still reads as one idea in his hands — the same claim broken sevenths is asking a single octave to make good on.