From caa6461b947f1cd0c9c837dfc310376bf101e046 Mon Sep 17 00:00:00 2001
From: Michael Goerz <mail@michaelgoerz.net>
Date: Wed, 29 Apr 2026 13:36:46 -0400
Subject: [PATCH] Add stub extension for Piccolo

---
 CLAUDE.md                       |  9 +++++++++
 Project.toml                    |  3 +++
 ext/QuantumControlPiccoloExt.jl | 26 ++++++++++++++++++++++++++
 test/Project.toml               |  1 +
 4 files changed, 39 insertions(+)
 create mode 100644 ext/QuantumControlPiccoloExt.jl

diff --git a/CLAUDE.md b/CLAUDE.md
index 0d1dceae..d33e9d4d 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -59,3 +59,12 @@ QuantumControl.jl is a high-level interface package that provides a coherent API
 - Tests for interfaces, propagation, optimization, parameterization, and workflows
 - Coverage reporting and CI integration
 - Downstream testing of Krotov and GRAPE packages
+
+
+## Docstrings
+
+The docstring for some function or type can be obtained from the fully qualified name, e.g. `QuantumControl.ControlProblem`:
+
+```bash
+julia --project=. -e 'using REPL; using QuantumControl; print(Base.doc(QuantumControl.ControlProblem))'
+```
diff --git a/Project.toml b/Project.toml
index 3e6245fc..ffae551b 100644
--- a/Project.toml
+++ b/Project.toml
@@ -17,12 +17,14 @@ UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 [weakdeps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
 FiniteDifferences = "26cc04aa-876d-5657-8c51-4c34ba976000"
+Piccolo = "c4671d76-df94-11ed-2057-43d4fd632fad"
 Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"
 
 [extensions]
 QuantumControlChainRulesCoreExt = "ChainRulesCore"
 QuantumControlFiniteDifferencesExt = "FiniteDifferences"
 QuantumControlZygoteExt = "Zygote"
+QuantumControlPiccoloExt = "Piccolo"
 
 [compat]
 FileIO = "1"
@@ -31,6 +33,7 @@ IOCapture = "0.2.4, 1"
 JLD2 = "0.4, 0.5, 0.6"
 LinearAlgebra = "1"
 Logging = "1"
+Piccolo = "1.8.0"
 Printf = "1"
 QuantumPropagators = ">=0.8.2"
 Zygote = "0.6, 0.7"
diff --git a/ext/QuantumControlPiccoloExt.jl b/ext/QuantumControlPiccoloExt.jl
new file mode 100644
index 00000000..06315074
--- /dev/null
+++ b/ext/QuantumControlPiccoloExt.jl
@@ -0,0 +1,26 @@
+module QuantumControlPiccoloExt
+
+import QuantumControl
+
+using Piccolo: QuantumSystem
+
+function QuantumControl.optimize(problem, method::Val{:Piccolo})
+    return piccolo_optimize(problem.trajectories, problem.tlist; problem.kwargs...)
+end
+
+
+function piccolo_optimize(trajectories, tlist; kwargs...)
+
+    if length(trajectories) == 1
+        return piccolo_optimize1(trajectories[1], tlist; kwargs...)
+    else
+        error("Multiple trajectories are currently not implemented for Piccolo")
+    end
+
+end
+
+function piccolo_optimize1(trajectory, tlist; kwargs...)
+    sys = QuantumSystem(H_drift, H_drives, drive_bounds)
+end
+
+end
diff --git a/test/Project.toml b/test/Project.toml
index f25c5a04..18e9f20f 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -27,6 +27,7 @@ LocalCoverage = "5f6e1e16-694c-5876-87ef-16b5274f298e"
 Logging = "56ddb016-857b-54e1-b83d-db4d58db5568"
 Optim = "429524aa-4258-5aef-a3af-852621145aeb"
 OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
+Piccolo = "c4671d76-df94-11ed-2057-43d4fd632fad"
 Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
 Plots = "91a5bcdd-55d7-5caf-9e0b-520d859cae80"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"