2023.10.19.

The respected Comrade

**"Scientific and technological strength is a state's most important strategic resource and a powerful propellant for social development."**

In general, a quantum network has several channels, therefore, it is of importance to study multi-channel quantum routers to transfer single photons from one channel to another. Until now, no research has been done on a scheme of quantum routing for single photons using the quantum dots coupled to the multi-channel with several junctions between them. Motivated by the above discussions, we proposed a new scheme of quantum routing for single plasmons with three quantum dots as quantum emitters coupled to multichannel plasmonic waveguides. We theoretically investigated the routing characteristic of the proposed hybrid system consisting of three quantum dots and plasmonic waveguides for the incident single plasmons via the real-space Hamiltonian model.

The proposed hybrid system in the paper consists of three quantum dots placed at the junctions between an infinite plasmonic waveguide (called the channel *a*) and the three semi-infinite plasmonic waveguides (called the channels *b, c* and *d*, respectively), where, for example, all the plasmonic waveguides could be metal nanowires, as shown in Figure. The three quantum dots (QD-1, QD-2 and QD-3) are placed in the infinite channel *a* at *z*=0, *L* and 2*L*, respectively, and the other semi-infinite channel, for example, b (c or d) is connected to the infinite channel *a* at *z*=0 (*z*=*L* or *z*=2*L*). It is also supposed that single plasmons are incident from the left of the channel a.

Fig. Scheme of quantum router

The total Hamiltonian of the hybrid system considered here can be written as H=H_{QD}+H_{PW}+H_{QD-PW}, where the first term describes the Hamiltonian of the three quantum dots, the second term describes the free Hamiltonian of the single plasmons propagating in all the plasmonic waveguide channels *b, c* and *d,* and the third term describes the interaction between the quantum dots and the single plasmons propagated in the plasmonic waveguide channels. Under the rotating approximation, one can have all the above Hamiltonians in real-space method.

We showed that the transfer rates into the semi-infinite channels could be equal probabilities or could be unit by adjusting the parameters, such as the couplings between quantum dots and channels, the spacing between quantum dots and the incident frequency of single plasmons. We also demonstrated that the semi-infinite channels in the proposed system exhibit the frequency selectivity. Based on the routing properties in the proposed system, it is a feasible scheme to realize a wavelength division multiplexing-like quantum router and it could be useful for designing the quantum devices and quantum information processing.

Our paper entitled "Wavelength Division Multiplexing-Like Quantum Routing for Single Plasmons in the Quantum Dots-Waveguides Hybrid System" (https://doi.org/10.1007/s10909-022-02812-x) was published in the Journal "Journal of Low Temperature Physics" of the Publishing Company "Springer".