  Given two copies of any quantum mechanical system, one may want to prepare
them in the thermofield double state for the purpose of studying thermal
physics or black holes. However, the thermofield double is a unique entangled
pure state and may be difficult to prepare. We propose a local interacting
Hamiltonian for the combined system whose ground state is approximately the
thermofield double. The energy gap for this Hamiltonian is of order the
temperature. Our construction works for any quantum system satisfying the
Eigenvalue Thermalization Hypothesis.
