At the mean-field level, the dynamics of a polariton condensate can be described by a type of nonlinear Schrodinger equation (Gross-Pitaevskii-type), for a classical (complex-number) wavefunction $\psi_{LP}$. Its form in momentum space reads:

\begin{multline}
i \frac{d}{dt}\psi_{LP}(k) =\left[\epsilon(k) 
-i\frac{\gamma(k)}{2}\right] \psi_{LP}(k) 
+F_{p}(k)\,\, e^{-i\omega_{p}t}  \\
+  \sum_{q_1,q_2} g_{k,q_1,q_2}\, \psi^{\star}_{LP}(q_1+q_2-k)
\, \psi_{LP}(q_1)\, \psi_{LP}(q_2).
\end{multline}

The function $\epsilon(k)$ is the dispersion of the particles (polaritons). The polaritons are a non-equilibrium system, due to their finite lifetime (damping rate $\gamma$). Therefore, they need continuous pumping with amplitude $F_p$ at energy $\omega_p$.
Finally, there exists a momentum-dependent nonlinear interaction $g_{k,q_1,q_2}$ that depends of the so-called Hopfield coefficients $X$ (simple functions of momentum) as:

\begin{equation}
g_{k,q_1,q_2}=g\, X^{\star}(k)\, X^{\star}(q_1+q_2-k)\, X(q_1)\, X(q_2)
\end{equation}

How can one transform the equation for $\psi$ to real-space?


Question: OSX ssh-agent: no password pasting, and problem with PKCS#8?
Answer: You can run a script like this in AppleScript Editor:

tell application "System Events" to tell process "SecurityAgent"
    set value of text field 2 of scroll area 1 of group 1 of window 1 to "pa55word"
    click button 2 of group 2 of window 1
end tell