diff --git a/biophysics/photon.py b/biophysics/photon.py
index 3fca0c7..43ffa44 100644
--- a/biophysics/photon.py
+++ b/biophysics/photon.py
@@ -41,3 +41,9 @@ def quanta(n):
c, a = canda(n) # get the creation and annihilation eigenstates
m = np.abs(a)**2 # m is mean number of quanta
return np.exp(-m) * m**(n) / factorial(n)
+
+def ham(p, q):
+ """
+ Mechanistic realization of the harmonic oscillator as a mass m hangign
+ from a spring with p and q momentum and position of the mass.
+ """