Room-Temperature Photon-Number-Resolved Detection Using A Two-Mode Squeezer*

We study the average intensity-intensity correlations signal at the output of a two-mode squeezing device with $|N\rangle\otimes|\alpha\rangle$ as the two input modes. We show that the input photon-number can be resolved from the average intensity-intensity correlations. In particular, we show jumps in the average intensity-intensity correlations signal as a function of input photon-number $N$. Therefore, we propose that such a device may be deployed as photon-number-resolving detector at room temperature with high efficiency.