- #1

Malamala

- 265

- 20

$$\psi = \frac{|0>+|1>}{\sqrt(2)}$$

If we put it in a chamber at a given temperature (say that the chamber has perfect vacuum) the system will lose its coherence due to the blackbody radiation from the chamber walls. So the density matrix will go (after a long amount of time) as:

$$

\begin{pmatrix}

1 & 1 \\ 1 & 1

\end{pmatrix} \rightarrow

\begin{pmatrix}

1 & 0 \\ 0 & 1

\end{pmatrix}

$$

I understand that decoherence happens as the informations leaks from the system in the environment. But I am not sure how do the blackbody photons learn about the superposition state of the system. I can imagine that a photon interacting with the 2 level system would learn about its position or momentum, but I am not sure what physical interaction would lead to the photon learning about the superposition state. Is the position/momentum related to the internal state of the system? Thank you!