logical-coupler-design SKILL.md skillA
logical-coupler-design from qutone/lightstim is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add qutone/lightstim/logical-coupler-design@git:20260526.75df926Pins git:20260526.75df926 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- qutone/lightstim
- Path
skills/logical-coupler-design/SKILL.md- Versions recorded
- 2
- Latest version
- git:20260526.75df926, committed May 26, 2026
- First version recorded
- May 26, 2026
- Size
- 10,961 bytes
- Repository stars
- 50
- License
- a license file GitHub does not identify
Design a new LogicalCouplerProtocol in LightStim to implement inter-patch joint measurements (lattice surgery). Use this skill when the user wants to: implement a new logical coupler for a code that doesn't have one yet, understand how the Unrotated Surface Code coupler works internally, design a coupler for a new code family (e.g. BB code logical measurement), or extend an existing coupler with a new boundary configuration. This skill is the key to replicating papers that describe custom…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Logical Coupler Design
## The core idea
A joint measurement between two logical patches (e.g. measuring ZZ = Z_L ⊗ Z_L) is
implemented by temporarily activating a "coupler patch" whose stabilizers span the
boundary between both patches. The coupler's joint stabilizers let the syndrome qubits
at the boundary "see" data qubits from both patches simultaneously, effectively measuring
the product of the two logical operators.
```
Before coupler:
[ctrl patch] | gap | [tgt patch]
Z_ctrl stabs ←gap→ Z_tgt stabs (boundary Z stabs face the gap)
After activate_coupler("zz"):
[ctrl patch] | corridor | [tgt patch]
(boundary stabs paused)
joint ZZ stabs now span both patch boundaries + corridor
```
The coupler patch is a factory output — it contains only the **corridor qubits and
boundary-redefined stabilizers**. It is registered inactive and activated/deactivated
during circuit construction.
---
## The `LogicalCouplerProtocol` interface
```python
from lightstim.ir.coupler import LogicalCouplerProtocol, LogicalCouplerPatch
from lightstim.ir.qec_patch import QECPatch
from typing import List
class MyProtocol(LogicalCouplerProtocol):
…Read the whole file at its exact version.
How to install
mdr add qutone/lightstim/logical-coupler-design@sha256:23c1877dd38036cdThe line at the top of this page pins the label git:20260526.75df926, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_rwgwyaneqkezw7sf)
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Versions
The registry has recorded 2 versions of this file, all committed on May 26, 2026.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260526.75df926 latest | 2026-05-26 | 75df926 | 10,961 B | A | view · diff |
| git:20260526.5b92aea | 2026-05-26 | 5b92aea | 10,934 B | A | view |
Audit of the latest version
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- pass: No zero-width or bidi control characters
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Source
qutone/lightstim · 50 stars · license a license file GitHub does not identify · pushed 2026-10-29 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_rwgwyaneqkezw7sf GET https://markdownregistry.com/api/v1/resolve?ref=qutone/lightstim/logical-coupler-design GET https://markdownregistry.com/api/v1/blob/23c1877dd38036cd4a62b502c987ece4a93c5029c7afabf5ea29268190e4bb8e
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