We demonstrate that the non-Hermitian Hamiltonian approach can be used as a universal tool to design and describe a performance of single photon quantum electrodynamical circuits(cQED). As an example of the validity of this method, we calculate a novel six port quantum router, constructed from 4 qubits and 3 open waveguides. We have got analytical expressions, which describe the transmission and reflection coefficients of a single photon in general form taking into account the non-uniform qubit's parameters. We show that, due to naturally derived interferences, it is possible to tune the probability of photon detection in different ports in-situ.We demonstrate that the non-Hermitian Hamiltonian approach can be used as a universal tool to design and describe a performance of single photon quantum electrodynamical circuits(cQED). As an example of the validity of this method, we calculate a novel six port quantum router, constructed from 4 qubits and 3 open waveguides. We have got analytical expressions, which describe the transmission and reflection coefficients of a single photon in general form taking into account the non-uniform qubit's parameters. We show that, due to naturally derived interferences, it is possible to tune the probability of photon detection in different ports in-situ.

arXiv:1812.06716Dec 17, 20180 citations

All-optical router at single-photon level by interference

Wei‐Bin Yan, Bao Liu, Ling Zhou +1 more

The realization of the all-optical router with multiple input ports and output ports will have direct application to achieve the quantum network. We present a scheme of all-optical routing of coherent-state photons in a waveguide-cavity coupled system. Our router has four input ports and four output ports. The routing of photons is based on the interference. The outcomes show that the transport of the coherent-state photons injected through any input port can be controlled by the phases of the coherent-state photons injected through other input ports. This control can be realized at the single-photon level and requires no additional control fields. Therefore, the all-optical routing at single-photon level can be achieved.The realization of the all-optical router with multiple input ports and output ports will have direct application to achieve the quantum network. We present a scheme of all-optical routing of coherent-state photons in a waveguide-cavity coupled system. Our router has four input ports and four output ports. The routing of photons is based on the interference. The outcomes show that the transport of the coherent-state photons injected through any input port can be controlled by the phases of the coherent-state photons injected through other input ports. This control can be realized at the single-photon level and requires no additional control fields. Therefore, the all-optical routing at single-photon level can be achieved.

Europhysics Letters (EPL)Sep 1, 201524 citations

Designable single-photon quantum routings with atomic mirrors

Xingmin Li, L. F. Wei

Quantum routers are the necessary elements of the quantum information network, and thus their routing capabilities are particularly important. With the atomic mirrors robustly controlling the reflected or transmitted coefficient of the waveguide photon, we show that a two-level atom can be served as an ideal quantum router to redirect a single photon from the input waveguide into the output waveguides (OWGs) with designable probabilities, e.g., $100%$ for one OWG, $1/2$ to one of the two OWGs, and $1/3$ to one of the three OWGs, etc.. The influence of the atomic dissipations on the routing capability is also discussed.Quantum routers are the necessary elements of the quantum information network, and thus their routing capabilities are particularly important. With the atomic mirrors robustly controlling the reflected or transmitted coefficient of the waveguide photon, we show that a two-level atom can be served as an ideal quantum router to redirect a single photon from the input waveguide into the output waveguides (OWGs) with designable probabilities, e.g., $100%$ for one OWG, $1/2$ to one of the two OWGs, and $1/3$ to one of the three OWGs, etc.. The influence of the atomic dissipations on the routing capability is also discussed.

Physical Review ADec 21, 201564 citations

Few-photon routing via chiral light-matter couplings

Ya Yang, Jing Lu, Lan Zhou

Abstract A quantum router is one of the essential elements in the quantum network. Conventional routers only direct a single photon from one quantum channel into another. Here, we propose a few-photon router. The active element of the router is a single qubit chirally coupled to two independent waveguides simultaneously, where each waveguide mode provides a quantum channel. By introducing the operators of the scatter-free space and the controllable space, the output state of the one-photon and two-photon scattering are derived analytically. It is found that the qubit can direct one and two photons from one port of the incident waveguide to an arbitrarily selected port of the other waveguide with unity, respectively. However, two photons cannot be simultaneously routed to the same port due to the anti-bunch effect.Abstract A quantum router is one of the essential elements in the quantum network. Conventional routers only direct a single photon from one quantum channel into another. Here, we propose a few-photon router. The active element of the router is a single qubit chirally coupled to two independent waveguides simultaneously, where each waveguide mode provides a quantum channel. By introducing the operators of the scatter-free space and the controllable space, the output state of the one-photon and two-photon scattering are derived analytically. It is found that the qubit can direct one and two photons from one port of the incident waveguide to an arbitrarily selected port of the other waveguide with unity, respectively. However, two photons cannot be simultaneously routed to the same port due to the anti-bunch effect.

Communications in Theoretical PhysicsDec 28, 20218 citations

Nonreciprocal single-photon quantum router

Ya-long Ren, Sheng-li Ma, Ji-kun Xie +3 more

The quantum router is an elementary building block in quantum information processing and quantum communication. This work constitutes a step forward in this direction, i.e., an efficient scheme is proposed for the implementation of a nonreciprocal single-photon quantum router, allowing the routing of a single photon from one side but blocking it from the other side. Our model consists of two directly coupled coplanar-waveguide resonators and a superconducting ring resonator, which are connected together through a transmission line. The nonreciprocity is realized by unidirectionally interacting the rotating microwave modes of the ring resonator with a dissipative magnon mode in an yttrium iron garnet disk. We find that a single-photon signal can be delivered from a given input port to either of the two output ports, but is fully absorbed from the opposite one. The proposed scheme not only enriches the family of nonreciprocal quantum devices, but also finds useful applications in chiral quantum technologies.The quantum router is an elementary building block in quantum information processing and quantum communication. This work constitutes a step forward in this direction, i.e., an efficient scheme is proposed for the implementation of a nonreciprocal single-photon quantum router, allowing the routing of a single photon from one side but blocking it from the other side. Our model consists of two directly coupled coplanar-waveguide resonators and a superconducting ring resonator, which are connected together through a transmission line. The nonreciprocity is realized by unidirectionally interacting the rotating microwave modes of the ring resonator with a dissipative magnon mode in an yttrium iron garnet disk. We find that a single-photon signal can be delivered from a given input port to either of the two output ports, but is fully absorbed from the opposite one. The proposed scheme not only enriches the family of nonreciprocal quantum devices, but also finds useful applications in chiral quantum technologies.

Physical Review AJan 14, 202266 citations

Quantum routing of single photons within a specified frequency range

Xin Zhang, Xingmin Li

The quantum routing of single photons takes the central role in an optical quantum network. The matching between the routing probability and the selected frequency of single photons limits the robustness and universality of the quantum router. Here, we investigate how to implement the quantum routing of single photons within bandwidth frequencies by two cavities embedding atoms acting as quantum nodes. We show that the routing capabilities of the single photons and the range of the frequencies can be manipulated by properly designing the chiral coupling strengths and the channel boundaries. Also, we demonstrate that the incident single photons, within bandwidth frequencies, can be completely routed to the targeted output port. This is particularly important to construct optical quantum networks within bandwidth frequencies in the future.The quantum routing of single photons takes the central role in an optical quantum network. The matching between the routing probability and the selected frequency of single photons limits the robustness and universality of the quantum router. Here, we investigate how to implement the quantum routing of single photons within bandwidth frequencies by two cavities embedding atoms acting as quantum nodes. We show that the routing capabilities of the single photons and the range of the frequencies can be manipulated by properly designing the chiral coupling strengths and the channel boundaries. Also, we demonstrate that the incident single photons, within bandwidth frequencies, can be completely routed to the targeted output port. This is particularly important to construct optical quantum networks within bandwidth frequencies in the future.

Physical Review AMay 6, 20243 citations

100%

for one OWG,

1/2

to one of the two OWGs, and

1/3

to one of the three OWGs, etc.. The influence of the atomic dissipations on the routing capability is also discussed.