Memory in quantum dot blinking

TL;DR

This paper demonstrates that quantum dot blinking exhibits non-trivial memory through temporal correlations, challenging simple Markovian models and suggesting multiple underlying physical mechanisms.

Contribution

It provides strong statistical evidence of non-trivial memory in quantum dot blinking and identifies three potential physical explanations for this phenomenon.

Findings

Quantum dot blinking data has non-trivial memory.

Memory cannot be explained by transition distribution alone.

Multiple physical mechanisms can account for observed memory.

Abstract

The photoluminescence intermittency (blinking) of quantum dots is interesting because it is an easily-measured quantum process whose transition statistics cannot be explained by Fermi's Golden Rule. Commonly, the transition statistics are power-law distributed, implying that quantum dots possess at least trivial memories. By investigating the temporal correlations in the blinking data, we demonstrate with high statistical confidence that quantum dot blinking data has non-trivial memory, which we define to be statistical complexity greater than one. We show that this memory cannot be discovered using the transition distribution. We show by simulation that this memory does not arise from standard data manipulations. Finally, we conclude that at least three physical mechanisms can explain the measured non-trivial memory: 1) Storage of state information in the chemical structure of a quantum dot; 2) The existence of more than two intensity levels in a quantum dot; and 3) The overlap in the intensity distributions of the quantum dot states, which arises from fundamental photon statistics.