Analysis of electron tunneling events with the hidden Markov model

The charge fluctuations of a quantum dot defined by depletion gates in a semiconductor heterostructure can be observed using a charge sensor. The charge sensor can observe electrons transiting on and off of the quantum dot in real time. From such data information about the quantum states of electrons on the dot can be inferred. We present an approach to analyzing charge sensor data based on the hidden Markov model (HMM). HMM theory provides a mathematical approach for inferring the details of a stochastic process from indirect observations. We discuss how this applies to the problem of charge sensor data analysis. We apply HMMs to data from a previous quantum dot experiment and demonstrate its usefulness in extracting the electron transition rates. Further potential for the HMM in the context of quantum dot experiments is discussed.