---
title: XYZ-symmetric SiN/SiO2 y-atom air-strip Q/V optimizer
---

# XYZ-symmetric SiN/SiO2 y-atom air-strip Q/V optimizer

**Worker:** not active · **stage:** `projected_q_over_v_continuation` ·
**status:** `stopped_by_request_final_validation` · **checkpoint age:** 5666.9 min

This paused campaign starts from density 0.5
in a 100 nm SiN design layer embedded between 300 nm SiO2 layers in a
16 µm × 2 µm design. A centered
y-oriented atom lies in an immutable one-micron vacuum strip through every
material layer. Full x/y/z symmetry leaves one octant and gives the unfolded
bright source pair unit total power. Raw Adam first minimizes the fixed absolute
temporal error. At step 50, a trustworthy Q≥100 activates the pole handoff. Stage B uses adaptive-trust L-BFGS-B to
maximize only `log(Q_harmonic)-log(V_atom/(lambda_pole/n_air)^3)` over every raw
topology pixel, the full SiN thickness, and the SiO2 thickness on each side.
The thickness map enforces `t_SiO2 >= t_SiN + 0.050 µm` for every proposal.
After the raw-pixel and tangent-binarity directions plateaued, Stage C switched
to conventional unfiltered tanh-projection continuation. It optimizes only Q/V
for six trials at fixed beta, raises beta by 0.5, and repeats from beta=1 to 32.
Near-binary bulk hands off by exact replay to a topology-preserving cubic-spline
level-set boundary, which then resumes direct Q/V optimization. There is no
spatial filter or binarity term in the scalar objective.



| quantity | current |
|---|---:|
| temporal Adam updates | 50 / at least 50 |
| pole accepted updates / trials | 528 / 1611 |
| Q | **23337.9** |
| best recorded Q (trust gate shown above) | 23408.9 |
| field / energy Q | 23337.9 / 23480.3 |
| Q-estimator ratio | 1.0061 |
| pole wavelength | 837.526 nm |
| source-center wavelength | 836.564 nm |
| field-monitor wavelength | **836.564 nm** |
| design-region slab thickness | **0.293695 µm** |
| Stage-B thickness coordinate / range | **True** / 0.050–0.500 µm |
| SiO2 thickness per side | **0.343712 µm** |
| Stage-B SiO2 coordinate / maximum | **True** / 1.000 µm |
| stack-thickness constraint | t_SiO2 − t_SiN ≥ 0.050 µm |
| SiO2 full width | **2 µm** |
| joint-stage SiO2 width coordinate / range | **False** / 2.000–2.000 µm |
| physical mode volume | 3.89716 µm³ |
| normalized mode volume | 6.63366 (λ_pole/n_air)³ |
| Q / normalized atom volume | **3528.81** |
| Purcell from Q/V | 268.157 |
| fitted atom-pole amplitude at source clear | **0.0641632** |
| absolute atom-trace peak / handoff | 0.122394 |
| source spectral power at pole / actual carrier | 0.844164 |
| reciprocal guided-Purcell proxy | **0.030625** |
| guided-Purcell proxy / handoff | **3902.89** |
| Stage-B volume treatment | **none — log Q / normalized atom volume is optimized** |
| three-window V span | 0.000118202 |
| active Q/V run time / window | — / — ps |
| gradient backend / storage | **`unknown`** / unresolved |
| structural backend decision | `not recorded` |
| exact reversible PML tape size | — GB |
| frozen measured value+gradient speedup | —x |
| Q/V fit start / nominal lifetime per window | — ps / — τ_amplitude |
| precision-triggered tape growths | 0 |
| final ringdown field-power / energy fraction | — / — |
| finite-step adjoint direction verified | **False** |
| ideal temporal fidelity | 0.483419 |
| active objective / value | **log Q / normalized atom volume** / 8.16871 |
| stage plateau / reason | **False** / `collecting_optimizer_memory` |
| plateau samples / evidence window | 0 / 0 |
| objective slope / detectable slope | — / — |
| trust-floor restarts since progress | 0 / 2 |
| practical fixed-beta Q/V gain over one memory | —% / 1% limit |
| practical plateau samples / required | 0 / 11 |
| practical trust radius still expanding | False |
| healthy / cumulatively pruned curvature pairs | **0 / 0** |
| L-BFGS / current-gradient predicted-ascent ratio | **—** |
| replay-triggered curvature recoveries | 0 |
| maximum last density motion | 0.0886365 |
| trust radius | 0.00961084 |
| binarity score (1 is binary) | **0.951442** |
| trainable gray fraction (0.05<rho<0.95) | **6.9299%** |
| archived tangent-stage Q/V floor | 694.152 |
| projection beta / eta | **20 / 0.5** |
| fixed-beta accepted Q/V updates / transition | 1 / objective plateau |
| material parameterization | `unfiltered_centered_tanh_projected_50nm_pixels` |
| hard atom access | **1.000 µm full-y air strip, immutable** |
| pixel / grid | 50 nm / [181, 35, 45] |
| non-PML z span / material-stack-to-PML air gap | 3.50 / 1.26 µm |
| z PML | 0.50 µm per side |
| z-padding convergence audit | `not_run` |
| 1.50→3.40 µm replay: residual / field-Q / energy-Q change | nan% / nan% / nan% |
| binarization / material projection / filter | **True / True / off** |
| physical waveguide escape eta | not part of the active objective |

## Q, V, objective, and optimizer history

![Q, V, objective, and motion](../_static/generated/atom_strip_cladded_qv_history.png)

The Q axis is linear. A pole is not trusted until the centered
Ey and total
energy decay estimates agree. Mode volume uses the geometric mean of their
three same-pole windows and the
same fitted pole wavelength; the local permittivity is exactly air by the hard
geometry constraint. The predecessor vacuum-clad branch is preserved as a qualified success at
Q=1,978, normalized atom volume 4.210, Q/V=469.9, and Purcell=35.71. Its frozen
atom-volume controller reached a trust-floor plateau; this campaign is a clean
three-material restart and does not inherit its geometry.





## Ideal and measured atom response

![Ideal and measured temporal response](../_static/generated/atom_strip_cladded_qv_response.png)

The target has fixed amplitude and phase for Q=10,000, beta one, V=0.1 µm³,
and perfect Ey-polarized overlap. It is not rescaled
to fit the simulation.

## Geometry and fields

![Initial, current, and difference geometry](../_static/generated/atom_strip_cladded_qv_geometry.png)

![Ey field profiles](../_static/generated/atom_strip_cladded_qv_fields.png)

## Downloadable layout

**Layout status:** provisional density-0.5-contour GDS preview. The ZIP includes the GDS, JSON stack/metric
manifest, and README. Before the spline handoff the GDS is intentionally marked
as a thresholded preview; after handoff it is the fabrication-oriented smooth
boundary representation. GDS is planar, so use the manifest for SiN and SiO2 thicknesses.

{download}`GDS bundle <../_static/downloads/atom_strip_cladded_qv/atom_strip_cladded_qv_gds_bundle.zip>`

{download}`Current GDS <../_static/downloads/atom_strip_cladded_qv/atom_strip_cladded_qv_current.gds>`

{download}`Layout manifest <../_static/downloads/atom_strip_cladded_qv/atom_strip_cladded_qv_manifest.json>`


{download}`Exact campaign methodology <../_static/downloads/atom_hole/METHOD_XYZ_Y_STRIP_CLADDED.md>`