From 1ff4e3286554202bbcebff987dda25d3ddfe15ff Mon Sep 17 00:00:00 2001
From: Ali <a_eghrari@yahoo.com>
Date: Mon, 13 May 2024 15:10:20 +0100
Subject: [PATCH] Handle single basis in embed

This commit addresses the issue where the `embed` function fails when it receives a single basis instead of a composite basis as input.
---
 src/operators.jl | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/operators.jl b/src/operators.jl
index ea824445..70513100 100644
--- a/src/operators.jl
+++ b/src/operators.jl
@@ -102,6 +102,20 @@ function embed(basis_l::CompositeBasis, basis_r::CompositeBasis,
     return Operator(basis_l, basis_r, data)
 end
 
+"""
+    embed(basis::Basis, indices, ops::AbstractOperator)
+
+Special case of the `embed` to handle embedding an operator `ops` into a single
+basis.
+"""
+function embed(basis::Basis, indices, ops::AbstractOperator)
+    if indices == 1 || indices == (1,) || indices == [1]
+        return ops
+    else
+        throw(ArgumentError("Invalid indices for single basis."))
+    end
+end
+
 """
     expect(op, state)