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Recently, quantum information science becomes one of the most interesting and promising fields for the reason that single photons are more extensively used as information carriers rather than the limited electrons. With the speed of light and their robustness against various sources of decoherence, photons are very widely used in quantum information processing by controlling the state of single photons. After the invention of the theoretical idea of a transistor based on the single photons, there has been a significant effort to explore the quantum devices, such as single photon transistors, single photon switches and atomic mirrors.
Nowadays, quantum network has become a topic of increasing interest for researchers in the fields of quantum information processing, such as quantum communication and quantum computation. Scalable quantum control of single photons provides us with rich ways of configuration of a quantum network which combines quantum routes with quantum nodes. A fundamental element inside a quantum node is just quantum router, which is an indispensable device for controlling the propagation of quantum signal at a single photon level, enabling us to deliver and distribute the quantum signals to the desired node with optimal control. However, quantum routing of signals (i.e., single photon states) is more complicated and architectural than controlling of single photons from one sender to another receiver.
In the last decade, lots of theoretical discussions and experimental considerations of a quantum router have been made in several systems, and with the rapid development of nanofabrication technology, proposals concerned on quantum routers have been realized experimentally. In recent years, lots of research works have been focused on exploring effective quantum reroute, both in theory and experiments. For a practical use, we are hoping for quantum router which can transport the incoming single photons with the required high feasibility, by which the propagating signals can be distributed efficiently to quantum channels.
As shown in Figure (a), we proposed a new constructive model of a single photon beam splitter and theoretically considered the properties of beam splitting based on classical-assisted cyclic transition of InGaAs/GaAs quantum dot coupled to the T-splitter silver nanowire. Here the quantum system has one input and two outputs and the three level InGaAs/GaAs quantum dot is placed in the turning point of two nanowires. In such a hybrid system, we can see that travel properties of incident single photons could be controlled by adjusting parameters, such as the intensity of the classical field, detunings, and the couplings between the semiconductor quantum dot and two nanowires. More interestingly, as shown in Figure (b) and (c), due to applying the classic field, the semiconductor quantum dot coupled to two quantum paths forms the classic-assisted cyclic transition, which plays an important role in rerouting single photons propagating along an input path. Our results also showed that it is possible to design an efficient single photon beam splitter with the wide-band transfer property and no reflection loss. Our proposed system could find further potential applications for realizing nano-optical and quantum information processing devices, such as quantum switches, quantum logic gates, directional coupler.
The article with our research results entitled "Realizable Single Photon Beam Splitter Based on Classical-Assisted Cyclic Transition of InGaAs/GaAs Quantum Dot Coupled to the T-Splitter Silver Nanowire"(https://doi.org/10.1007/s11468-021-01459-w) was published in the Journal "Plasmonics" of the Publishing Company "Springer".