# Superposition at absolute zero

• B

http://arxiv.org/abs/quant-ph/0505056
http://physics.bu.edu/~mohanty/physica-decoherence.pdf

Since I cant make much out of them, maybe except this interesting phrase in the first one

"First
of all it is intriguing that even at
absolute zero a coherent superposition of states can get destroyed by zero point fluctuations
."

But this, I dont understand what they mean by this:

"At absolute zero the quantum system
can only lose energy to the
cold environment"

And another question : From what I know, the more atoms you try to put in superposition, you need to get them closer to absolute zero, so can one deduce that theoretically at absolute zero you could have the whole universe in a superposition state ?

$$|\psi(t) \rangle=\exp(-\mathrm{i} \hat{H} t) |\psi_0 \rangle.$$
$$\hat{\rho}_{\text{can}}=\frac{1}{Z} \exp \left (-\frac{\hat{H}}{T} \right ), \quad Z=\mathrm{Tr}\exp \left (-\frac{\hat{H}}{T} \right ) .$$