From 6c90fb30318ad87c1a60ff1e11751c462b336dbe Mon Sep 17 00:00:00 2001
From: Angela Riva <62027430+angelariva@users.noreply.github.com>
Date: Tue, 30 Apr 2024 17:31:43 +0200
Subject: [PATCH] Update theory.md

---
 docs/src/theory.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/docs/src/theory.md b/docs/src/theory.md
index 357c3c2..a3a8311 100644
--- a/docs/src/theory.md
+++ b/docs/src/theory.md
@@ -95,7 +95,9 @@ The Hamiltonian of the system interacting with this extended bath now includes t
 
 This method simplifies the simulation of finite temperature effects by treating them within an effective zero-temperature framework, thereby keeping the computational advantages of using pure states.
 
+### Finite temperature with the thermofield transformation
 
+Write about thermofield transfomation [^devega_thermo_2015].
 
 ## Computation of the chain coefficients
 
@@ -263,3 +265,6 @@ The major advantage of this method is that it naturally preserves the unitarity
 
 [^appel_mathematics_2007]:
     > Appel, W. Mathematics for Physics and Physicists; Princeton University Press, 2007.
+
+[^devega_thermo_2015]
+    > de Vega, I.; Banuls, M-.C. Thermofield-based chain-mapping approach for open quantum systems. Phys. Rev. A 2015, 92 (5), 052116. https://doi.org/10.1103/PhysRevA.92.052116.