Strong Coupling Competition in a Triple Rabi Splitting System and Used as a Biosensor

Strong coupling between plasmons and multiple exciton states (MES) is important in multiqubit creation and manipulation; therefore, it is highly desired in multiqubit quantum information processing. Although strong coupling between plasmons and two exciton states has been achieved in some plasmonic nanostructures, it remains difficult to clearly demonstrate the strong coupling between plasmons and three or more exciton states. Additionally, the practical applications of these plasmon-MES strong coupling systems have remained elusive, which need to be further exploited. Here, we achieved strong coupling between a plasmon mode and three different exciton states, showing a clear triple Rabi splitting. Then, we demonstrate an interesting phenomenon of strong coupling competition between two exciton states and the plasmon mode by coating three kinds of J-aggregates over plasmonic nanoparticles, which have been attempted to be used as a reporter for biomacromolecule detecting. Our findings not only contribute a test bed in exploiting the multiqubit strong coupling but also represent a step toward the practical applications of the plasmon-MES strong coupling system.