---
title: XYZ-symmetric SiN y-atom air-strip volume-constrained Q optimizer
---

# XYZ-symmetric SiN y-atom air-strip volume-constrained Q optimizer

**Worker:** not active · **stage:** `pole_q_volume_constrained` ·
**status:** `qualified_success_paused_resumable` · **checkpoint age:** 11.1 min

This paused campaign drives the even bright combination of two fundamental
TE-like modes into a 16 µm × 2 µm ×
0.5 µm SiN design. A centered y-oriented atom lies in
an immutable one-micron-wide air strip spanning the complete y width, so the
optical path cannot route through dielectric around the atom. Full x/y/z
symmetry leaves one octant and the unfolded coherent source pair has unit
incident power. Raw Adam first minimizes the fixed absolute temporal error.
At step 50, a trustworthy Q≥100 activates the pole handoff. Stage B jointly optimizes every in-plane density pixel
and one global slab-thickness coordinate while maximizing only the moving-pole
harmonic Q. The design-region thickness moves continuously from 0.2 to 0.7 µm
through a planar subpixel fill; the external 0.5 µm feedthrough remains fixed.
Every
Q direction is projected into the local non-increasing-`log(V_atom)`
half-space, and a forward replay rejects any candidate above the one fixed
handoff-volume ceiling. The 0.2% allowance is only for estimator noise and
never ratchets. No filter, material projection, or binarization is active.

| quantity | current |
|---|---:|
| temporal Adam updates | 50 / at least 50 |
| pole accepted updates / trials | 118 / 1683 |
| Q | **1977.9** |
| best trusted Q | 1977.9 |
| field / energy Q | 1977.9 / 1978.39 |
| Q-estimator ratio | 1.00025 |
| pole wavelength | 821.989 nm |
| source-center wavelength | 821.842 nm |
| design-region slab thickness | **0.7 µm** |
| Stage-B thickness coordinate / range | **True** / 0.200–0.700 µm |

| physical mode volume | 2.33794 µm³ |
| normalized mode volume | 4.20954 λ_pole³ |
| Q / normalized atom volume | **469.918** |
| Purcell from Q/V | 35.7095 |
| cavity-emission probability C/(1+C) | 97.2759% |
| Purcell target / reached | 100 / **False** |
| lowest Q found with Purcell≥100 | — |
| frozen handoff mode volume | 2.94334 µm³ |
| last candidate volume-feasible | **True** |
| fitted atom-pole amplitude at source clear | **0.0684753** |
| absolute atom-trace peak / handoff | 0.35553 |
| source spectral power at pole / center | 0.995725 |
| reciprocal guided-Purcell proxy | **0.000204587** |
| guided-Purcell proxy / handoff | **61799.2** |
| Stage-B volume treatment | **2.94334 µm³ handoff ceiling with 0.2% fit-noise allowance** |
| three-window V span | 0.000106879 |
| ideal temporal fidelity | 0.489826 |
| active objective | 7.58991 |
| maximum last density motion | 1.19209e-06 |
| trust radius | 0.0003 |
| hard atom access | **1.000 µm full-y air strip, immutable** |
| pixel / grid | 50 nm / [181, 35, 27] |
| non-PML z span / material-stack-to-PML air gap | 1.70 / 0.50 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 / projection / filter | **off / off / 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_temporal_collection_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 their same final window and the
same fitted pole wavelength; the local permittivity is exactly air by the hard
geometry constraint. The first air-strip Stage-B attempt is archived as a negative ablation. Its
collection score rose 442.6× and Q rose 268→10,027, but physical atom volume
rose 4.289→100.02 µm³ and Purcell only rose 2.26→3.76. Because no parameter
snapshot existed at that handoff, this corrected branch starts fresh from a
density-zero air design, stores its new handoff explicitly, and then applies
the frozen-volume Q controller.

## Ideal and measured atom response

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

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

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