Trapped ions technology is the most promising candidate for construction of the large-scale quantum computers, quantum repeaters and quantum networks. Quantum networks require matter qubits with fast quantum gates and measurement, efficient coupling to photons and low gate error rates. There was growing progress in two-species ion trapping [1], where one ion acts as a communication qubit that can be efficiently entangled to photon and the other one used as excellent quantum memories allowing efficient local processing. However, the photonic interface needed for communication ions must not affect the state of the quantum memory ion. In a recent experimental breakthrough, the isolation between quantum memory ion (171Yb+) and communication ion (138Ba+) was achieved and a quantum state transfer between the ions has been demonstrated.Trapped ions technology is the most promising candidate for construction of the large-scale quantum computers, quantum repeaters and quantum networks. Quantum networks require matter qubits with fast quantum gates and measurement, efficient coupling to photons and low gate error rates. There was growing progress in two-species ion trapping [1], where one ion acts as a communication qubit that can be efficiently entangled to photon and the other one used as excellent quantum memories allowing efficient local processing. However, the photonic interface needed for communication ions must not affect the state of the quantum memory ion. In a recent experimental breakthrough, the isolation between quantum memory ion (171Yb+) and communication ion (138Ba+) was achieved and a quantum state transfer between the ions has been demonstrated.

IEEE/LEOS Summer Topical MeetingsJul 1, 20182 citations

Trapped-ion-based quantum repeater node across a 17 km metropolitan fiber

K. Fabitha, T. Runggaldier, A. Winkler +7 more

Concatenation of quantum repeater nodes has been proposed as a means to distribute entanglement efficiently across future long-distance networks. Here, we demonstrate a trapped-ion repeater node that establishes photonic entanglement over a 17 km fiber traversing a city, moving beyond laboratory-only prototypes. The node comprises two atomic ions coupled to an optical cavity. First, a detailed characterization is performed of the long fiber channel and of ion-photon entanglement distributed across it. Next, a repeater-node protocol is implemented, achieving entanglement between a local photon and a remote photon with a Bell-state fidelity of $81.6^{+1.9}_{-1.4}\%$ . These results demonstrate that trapped-ion repeater-node technology can operate over existing city-scale fiber infrastructure and represent a step toward distributed quantum repeater networks.Concatenation of quantum repeater nodes has been proposed as a means to distribute entanglement efficiently across future long-distance networks. Here, we demonstrate a trapped-ion repeater node that establishes photonic entanglement over a 17 km fiber traversing a city, moving beyond laboratory-only prototypes. The node comprises two atomic ions coupled to an optical cavity. First, a detailed characterization is performed of the long fiber channel and of ion-photon entanglement distributed across it. Next, a repeater-node protocol is implemented, achieving entanglement between a local photon and a remote photon with a Bell-state fidelity of $81.6^{+1.9}_{-1.4}\%$. These results demonstrate that trapped-ion repeater-node technology can operate over existing city-scale fiber infrastructure and represent a step toward distributed quantum repeater networks.

quant-pharXiv:2610.27854Oct 21, 20260 citations

Quantum networking with trapped ions and photons

Dzmitry Matsukevich

Bulletin of the American Physical SocietyMay 22, 20090 citations

Quantum repeater node with free-space coupled trapped ions

Max Bergerhoff, Omar Elshehy, Stephan Kucera +2 more

Quantum repeater cells are crucial for overcoming loss in long-distance quantum networks. Here, the authors present a trapped-ion implementation of a quantum repeater cell, using two ${}^{40}$ Ca ${}^{+}$ ions that act as quantum memories and are coupled to free-space photonic channels. With this setup they are able to demonstrate asynchronous generation of atom-photon and photon-photon entanglement.Quantum repeater cells are crucial for overcoming loss in long-distance quantum networks. Here, the authors present a trapped-ion implementation of a quantum repeater cell, using two ${}^{40}$Ca${}^{+}$ ions that act as quantum memories and are coupled to free-space photonic channels. With this setup they are able to demonstrate asynchronous generation of atom-photon and photon-photon entanglement.

arXiv:2312.14805Physical Review ASep 3, 20245 citations

Ion-trap single-photon source for quantum networks

Tracy E. Northup, H. G. Barros, Andreas Stute +2 more

Bulletin of the American Physical SocietyMay 20, 20090 citations

81.6^{+1.9}_{-1.4}\%

. These results demonstrate that trapped-ion repeater-node technology can operate over existing city-scale fiber infrastructure and represent a step toward distributed quantum repeater networks.

Quantum repeater cells are crucial for overcoming loss in long-distance quantum networks. Here, the authors present a trapped-ion implementation of a quantum repeater cell, using two

{}^{40}

{}^{+}

ions that act as quantum memories and are coupled to free-space photonic channels. With this setup they are able to demonstrate asynchronous generation of atom-photon and photon-photon entanglement.