Reliability of correlation-based SMSV modal characterization under experimental imperfections

Determine the reliability of the second- and third-order correlation-function method for characterizing the number of modes in single-mode squeezed-vacuum states in the presence of experimental imperfections.

Background

The paper estimates the effective mode number of the generated single-mode squeezed-vacuum states from the relationship between the pulse-integrated second- and third-order correlation functions, obtaining a mode number of approximately 1.24. The authors argue that this method may be more reliable than joint-spectral-intensity or second-order-correlation approaches because the divergent correlation values at low mean photon number represent the desired modal signal rather than a dominant noise source.

However, the experiment and accompanying theory include imperfections such as nonideal polarization separation, detector saturation, attenuation, and limited photon-number resolution. The reliability of the proposed correlation-based characterization method under such realistic imperfections has not been established and is explicitly deferred for future work.