Full counting statistics as a probe of quantum coherence in a side-coupled double quantum dot system

• The FCS can be used to probe the quantum coherence of side-coupled double QD system.
• Probing quantum coherence using FCS may permit experimental tests in the near future.
• The current noise characteristics depend on the quantum coherence of this QD system.
• The super-Poissonian noise can be enhanced when considering conduction electron spin.
• The side-coupled double QD system suggests a tunable super-Poissonian noise device.

We study theoretically the full counting statistics of electron transport through side-coupled double quantum dot (QD) based on an efficient particle-number-resolved master equation. It is demonstrated that the high-order cumulants of transport current are more sensitive to the quantum coherence than the average current, which can be used to probe the quantum coherence of the considered double QD system. Especially, quantum coherence plays a crucial role in determining whether the super-Poissonian noise occurs in the weak inter-dot hopping coupling regime depending on the corresponding QD-lead coupling, and the corresponding values of super-Poissonian noise can be relatively enhanced when considering the spins of conduction electrons. Moreover, this super-Poissonian noise bias range depends on the singly-occupied eigenstates of the system, which thus suggests a tunable super-Poissonian noise device. The occurrence-mechanism of super-Poissonian noise can be understood in terms of the interplay of quantum coherence and effective competition between fast-and-slow transport channels.