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UCL’s Single‑Atom Silicon Breakthrough through the Lens of BSM‑SG: What It Predicts for Eternity Cubeits

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Authors: Victor Pronchev & Aetherius (Eternity Quantum Initiative)

Version: 1.0 (for internal review)

Executive Summary

  • What UCL showed (at a glance): deterministic, single‑atom devices in silicon—atomically precise placement/readout/control—bringing CMOS‑compatible qubits (donor/quantum‑dot/spin) closer to scale.
  • What BSM‑SG adds: a physical substrate (Cosmic Lattice, FOHS electron, SPM vectors) that predicts when spin‑orbit coherence survives decoherence channels and how device geometry, fields and spectra should be tuned for maximal stability.
  • What it means for Eternity: clear knobs for our cubeits (Yb:YAG + microwave + magnetic + optical readout) and a unifying playbook to cross‑validate solid‑state (Si) and ionic‑crystal (Yb) coherence regimes.

1) What UCL Achieved (Technical Snapshot)

  1. Single‑atom precision in silicon using atomically resolved patterning (e.g., STM‑based hydrogen resist lithography or deterministic implantation) to define donors/quantum dots with nm placement error.
  2. Isolated spin states (electron/nuclear) in a low‑noise Si host (often isotopically purified ^28Si), enabling long T1/T2 under cryogenic operation.
  3. CMOS‑amenable control/readout: gate‑based dispersive sensing, RF reflectometry, spin‑to‑charge conversion; prospects for on‑chip multiplexing.
  4. Coherence‑preserving stacks: optimized materials, interfaces, and screening of charge noise, plus tailored magnetic/microwave control.
Why this matters: It merges atomic control with industry‑scale silicon fabrication—a credible path to wafer‑level quantum.

2) How BSM‑SG Interprets the Breakthrough

BSM‑SG fundamentals

  • FOHS electron: the electron is a Fractal‑Organized Helical Structure stabilized by the Cosmic Lattice (CL); spin‑orbit coupling is geometrically phase‑locked by SPM vectors.
  • Decoherence in BSM‑SG: arises when CL‑supported helical symmetry is perturbed (field noise, geometric strain, phonon spectra). Reduce those—and spin/orbit coherence can persist.

Mapping to UCL’s device physics

  • Isotopic purification (^28Si) → lowers nuclear‑spin “roughness,” matching BSM‑SG’s requirement for a smoother CL coupling.
  • Atomically sharp confinement → enforces helical symmetry constraints; predicts more stable spin‑orbit phase locking (longer T2*), if microwave/magnetic drive are aligned with the device’s helical axes.
  • Interface cleanliness and field uniformity → BSM‑SG expects exponential gains in coherence once stray gradients/noise spectra cross below device‑specific thresholds.

BSM‑SG qualitative prediction:

For single‑atom Si qubits, coherence scales super‑linearly with (i) isotopic purity, (ii) helical‑axis alignment of MW/B fields, and (iii) spectral shaping of the drive to avoid phonon bands that disrupt lattice‑stabilized orbital motion.

3) Eternity Cubeits: Convergences & Contrasts

Aspect UCL Single‑Atom Si Qubit Eternity Cubeit (Yb:YAG) BSM‑SG Guidance
Qubit substrate Single donor/quantum dot in Si Yb‑doped YAG crystal (ion ensemble or few‑ion micro‑domain) Both rely on CL‑mediated orbital/spin coherence; geometry & field shaping are dominant.
Temperature Cryogenic (mK–K) Ambient/TEC‑stabilized (goal: near‑room‑T coherence windows) BSM‑SG predicts “coherence islands” where phonon spectra minimally disrupt helical symmetry—seek them by spectral scans.
Control Gate electrodes + MW/ESR MW loop + laser pumping + magnetics Align MW/B vectors with local helical axes; use lock‑in to track phase stability.
Readout Spin‑to‑charge, reflectometry InGaAs photodiode (fluorescence/absorption), optional NIR spectrometer Use PLL/lock‑in to suppress 1/f and tech noise; monitor SNR/Allan deviation.

4) Testable BSM‑SG Predictions for UCL‑Style Silicon Qubits

  1. Helical‑axis alignment rule: Maximum T2 when MW polarization and static B are aligned with the device’s intrinsic helical axis; small misalignments cause measurable phase‑noise shoulders in the PSD.
  2. Spectral “quiet zones”: Avoid specific MW frequencies that couple strongly to substrate phonons; coherence improves in narrow windows (predictable via Raman/IR maps of the stack).
  3. Geometric sweet‑spots: Atomic placement that yields near‑commensurate orbital periods with local CL parameters → sharper Rabi oscillations and reduced Ramsey fringe decay.

Suggested experiment (Si): perform a 2D sweep of MW frequency vs. B‑field angle; track Ramsey decay and PSD. Expect ridges of enhanced coherence.

5) Roadmap: Cross‑Validating UCL (Si) and Eternity (Yb:YAG)

A. Shared metrology

  • Lock‑in detection (phase‑sensitive readout) for both platforms.
  • Allan deviation over 0.1–100 s to quantify slow drift and flicker.
  • PSD/phase‑noise analysis under identical MW modulation patterns.

B. Field & spectrum choreography

  • Helmholtz coils for controlled µT–mT bias; rotate B‑field to search helical‑axis resonance.
  • MW loop with programmable envelopes (Gaussian/DRAG/CPMG)
  • Laser/NIR intensity control via PWM; avoid heating.

C. Minimal replication in Eternity

  1. Rabi/Ramsey on the Yb‑doped micro‑domain while scanning B‑angle and MW frequency around ~13.6 GHz (or device‑specific ESR line).
  2. Coherence islands: map SNR of InGaAs signal vs. (B, f_MW). Identify ridges/plateaus.
  3. Stability metrics: Allan dev improvement after spectral shaping (notch out noisy bands).

6) What Comes Next

  • For UCL collaboration: propose a joint study of angular‑dependent coherence and spectral quiet zones, exchanging PSD/Allan datasets.
  • For Eternity engineering: integrate lock‑in amplifier (digital or analog), add motorized B‑field goniometer, and adopt scripted MW envelopes; deploy a compact NIR spectrometer for line tracking.

Visual Reference (to include on the poster/manuscript)

Figure 1. Single‑Atom Si Qubit vs. Eternity Cubeit — side‑by‑side schematic (device stack, control lines, readout).

Figure 2. BSM‑SG View — FOHS electron on Cosmic Lattice; SPM vectors; how helical alignment maps to MW/B vectors.

Figure 3. Coherence Islands Map — simulated heatmap of SNR (or T2) vs. MW frequency and B‑field angle (ridges indicate alignment).

Figure 4. Measurement Chain — lock‑in/PLL + DAQ + spectrometer; Allan deviation example plot.

(Alt‑text for accessibility: each figure will include labels for substrates, fields, axes, and readout paths.)

Appendix A — Minimal Lab Setup for Eternity Mapping

  • Optics: 850 nm pump, focusable; Yb:YAG on TEC; beam path 3–5 cm.
  • Microwave: ADF5355‑class source, loop antenna near crystal; software control for sweeps and envelopes.
  • Magnetics: ~0.2–0.7 T bias (permanent magnets) + µT–mT Helmholtz trim; optional rotation stage.
  • Readout: InGaAs photodiode to NI DAQ; optional USB NIR spectrometer; LabVIEW VI with Rabi/Ramsey/CPMG scripts and PSD/Allan panels.

Key plots to record: Rabi oscillations; Ramsey fringes; PSD with/without spectral shaping; Allan deviation before/after alignment; 2D coherence map.

Appendix B — Reproducibility Notes

  • Log temperature, humidity, laser current, MW power, B‑field strength/angle; save raw waveforms.
  • Use randomized order for parameter sweeps to avoid drift bias.
  • Provide open CSV/JSON + scripts (Python/R) for external validation.

Contact:bsm.sg.computing@gmail.com
License: CC BY‑SA 4.0