On amplifying and counting bosons
S. J. van Enk, Tzula B. Propp · arXiv (Cornell University) · 2018
We show that detection of single photons is not subject to the fundamental limitations that accompany quantum linear amplification of bosonic mode amplitudes, even though a photodetector does amplify a few-photon input signal to a macroscopic output signal. Alternative limits are derived for nonlinear photon-number amplification with optimistic implications for single-photon detection. Our description makes clear that nonlinear amplification takes place, in general, at a different frequency $\omega'$ than the frequency $\omega$ of the input photons, which can be exploited to suppress thermal noise even further. A practical example that fits our description very well is electron shelving.