We show how to generate Bell states and $N$ -partite $W$ states of long-distance superconducting (SC) qubits in a SC waveguide QED system, where SC qubits are coupled to an open microwave transmission line. In the two-qubit case, the Bell state of two long-distance qubits can be a dark state of the system by choosing appropriate system parameters. If one proper microwave pulse drives one of two qubits, the two qubits will evolve from their ground states to a Bell state. Further, we extend this scheme to the multiqubit case. We show that $W$ states of $N$ long-distance qubits can also be generated. Because both the Bell and $W$ states are decoupled from the waveguide (i.e., dark states of the system), they are steady and have very long lifetimes in the ideal case without decoherence of qubits. In contrast to the ideal case, the presence of decoherence of qubits limits the lifetimes of the Bell and $W$ states. Our study provides an alternative scheme for generating Bell states and $N$ -partite $W$ states in SC waveguide QED, which can be used to entangle long-distance nodes in waveguide quantum networks.We show how to generate Bell states and $N$-partite $W$ states of long-distance superconducting (SC) qubits in a SC waveguide QED system, where SC qubits are coupled to an open microwave transmission line. In the two-qubit case, the Bell state of two long-distance qubits can be a dark state of the system by choosing appropriate system parameters. If one proper microwave pulse drives one of two qubits, the two qubits will evolve from their ground states to a Bell state. Further, we extend this scheme to the multiqubit case. We show that $W$ states of $N$ long-distance qubits can also be generated. Because both the Bell and $W$ states are decoupled from the waveguide (i.e., dark states of the system), they are steady and have very long lifetimes in the ideal case without decoherence of qubits. In contrast to the ideal case, the presence of decoherence of qubits limits the lifetimes of the Bell and $W$ states. Our study provides an alternative scheme for generating Bell states and $N$-partite $W$ states in SC waveguide QED, which can be used to entangle long-distance nodes in waveguide quantum networks.

arXiv:2302.06204Physical Review AppliedOct 5, 202321 citations

A hybrid-system approach for W state and cluster state generation

Xin Tong, Chuan Xi Wang, Cong Cao +2 more

Optics CommunicationsAug 12, 201313 citations

All-photonic quantum repeater for multipartite entanglement generation

Chenlong Li, Yao Fu, Wen‐Bo Liu +5 more

Quantum network applications such as distributed quantum computing and quantum secret sharing represent a promising future network equipped with quantum resources. Entanglement generation and distribution over long distances are critical and unavoidable when utilizing quantum technology in a fully connected network. The distribution of bipartite entanglement over long distances has seen some progress, while the distribution of multipartite entanglement over long distances remains unsolved. Here we report a two-dimensional quantum repeater protocol for the generation of multipartite entanglement over long distances with an all-photonic framework to fill this gap. The entanglement generation yield remains proportional to the transmission efficiency regardless of the number of network users and shows long transmission distance under various numbers of network users. With the improved efficiency and flexibility of extending the number of users, we anticipate that our protocol can work as a significant building block for quantum networks in the future.Quantum network applications such as distributed quantum computing and quantum secret sharing represent a promising future network equipped with quantum resources. Entanglement generation and distribution over long distances are critical and unavoidable when utilizing quantum technology in a fully connected network. The distribution of bipartite entanglement over long distances has seen some progress, while the distribution of multipartite entanglement over long distances remains unsolved. Here we report a two-dimensional quantum repeater protocol for the generation of multipartite entanglement over long distances with an all-photonic framework to fill this gap. The entanglement generation yield remains proportional to the transmission efficiency regardless of the number of network users and shows long transmission distance under various numbers of network users. With the improved efficiency and flexibility of extending the number of users, we anticipate that our protocol can work as a significant building block for quantum networks in the future.

arXiv:2212.05224Optics LettersFeb 1, 202314 citations

Communication Capacity of W States

Junxia Li

International Journal of Theoretical PhysicsFeb 9, 20181 citation

Influence of Actual Transmission Distance on Quantum Key Distribution System

WU Jia-na

A long distance peer to peer quantum key distribution experimental system of polarization encoding was built based on BB84 protocol.With the help of this experimental platform,quantum key distribution experiment with 5,10,15 km three different transmission distances was completed and the main parameters of the system was collected in real time for data analysis.The experimental results show that with the increase of quantum fiber channel distance from sending end to receiving end,the system bit generation rate and the amount of key generated by the system would drop,the bit error rate of signal state and decoy state would increase within statistical time.The experimental results have theoretical and practical value for practical development of the long-range security quantum key distribution system.A long distance peer to peer quantum key distribution experimental system of polarization encoding was built based on BB84 protocol.With the help of this experimental platform,quantum key distribution experiment with 5,10,15 km three different transmission distances was completed and the main parameters of the system was collected in real time for data analysis.The experimental results show that with the increase of quantum fiber channel distance from sending end to receiving end,the system bit generation rate and the amount of key generated by the system would drop,the bit error rate of signal state and decoy state would increase within statistical time.The experimental results have theoretical and practical value for practical development of the long-range security quantum key distribution system.

Journal of Jilin University(Science Edition)Jan 1, 20140 citations

Transitionless-based shortcuts for the fast and robust generation of W states

Ye‐Hong Chen, Bi‐Hua Huang, Jie Song +1 more

arXiv:1505.04372Optics CommunicationsJun 10, 201630 citations

We show how to generate Bell states and

N

-partite

W

states of long-distance superconducting (SC) qubits in a SC waveguide QED system, where SC qubits are coupled to an open microwave transmission line. In the two-qubit case, the Bell state of two long-distance qubits can be a dark state of the system by choosing appropriate system parameters. If one proper microwave pulse drives one of two qubits, the two qubits will evolve from their ground states to a Bell state. Further, we extend this scheme to the multiqubit case. We show that

W

states of

N

long-distance qubits can also be generated. Because both the Bell and

W

states are decoupled from the waveguide (i.e., dark states of the system), they are steady and have very long lifetimes in the ideal case without decoherence of qubits. In contrast to the ideal case, the presence of decoherence of qubits limits the lifetimes of the Bell and

W

states. Our study provides an alternative scheme for generating Bell states and

N

-partite

W

states in SC waveguide QED, which can be used to entangle long-distance nodes in waveguide quantum networks.