Quantum polyspectra approach to the dynamics of blinking quantum emitters at low photon rates without binning: Making every photon count

The blinking statistics of quantum emitters and their corresponding Markov models play an important role in high-resolution microscopy of biological samples as well as in nano-optoelectronics and many other fields of science and engineering. Current methods for analyzing the blinking statistics like the full counting statistics and the Viterbi algorithm break down for low photon rates. We present an evaluation scheme that eliminates the need for both a minimum photon flux and the usual binning of photon events which limits the measurement bandwidth. Our approach is based on higher-order spectra of the measurement record which we model within the recently introduced method of quantum polyspectra from the theory of continuous quantum measurements. By virtue of this approach we can determine on- and off-switching rates of a semiconductor quantum dot at light levels 1000 times lower than in a standard experiment and 20 times lower those than achieved with a scheme from full counting statistics. Thus, a very powerful high-bandwidth approach to the parameter-learning task of single-photon hidden Markov models is established with applications in many fields of science.