Towards high-fidelity interference of photons emitted by two remotely trapped Rb-87 atoms

Rosenfeld, Wenjamin; Hofmann, Julian; Ortegel, Norbert; Krug, Michael; Henkel, Florian; Kurtsiefer, Christian; Weber, Markus; Weinfurter, Harald

doi:10.1134/s0030400x11110233

Cited by 6 publications

(4 citation statements)

References 14 publications

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“…Weighting the resulting contrasts with the probability distribution for the herald photons yields the average contrast C, which is 0.97 in this case. This two-photon interference contrast can be converted into a remote-entanglement fidelity F = 1 2 (1 + C) under the assumption that all other processes are perfect [36]. Thus, a fidelity of close to 0.99 should be achievable with our model parameters.…”

Section: A Numerical Calculation Of the Photon Indistinguishabilitymentioning

confidence: 96%

An integrated quantum repeater at telecom wavelength with single atoms in optical fiber cavities

et al. 2016

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Quantum repeaters promise to enable quantum networks over global distances by circumventing the exponential decrease in success probability inherent in direct photon transmission. We propose a realistic, functionally integrated quantum-repeater implementation based on single atoms in optical cavities. Entanglement is directly generated between the single-atom quantum memory and a photon at telecom wavelength. The latter is collected with high efficiency and adjustable temporal and spectral properties into a spatially well-defined cavity mode. It is heralded by a near-infrared photon emitted from a second, orthogonal cavity. Entanglement between two remote quantum memories can be generated via an optical Bell-state measurement, while we propose entanglement swapping based on a highly efficient, cavity-assisted atom-atom gate. Our quantum-repeater scheme eliminates any requirement for wavelength conversion such that only a single system is needed at each node. We investigate a particular implementation with rubidium and realistic parameters for Fabry-Perot cavities based on CO 2 laser-machined optical fibers. We show that the scheme enables the implementation of a rather simple quantum repeater that outperforms direct entanglement generation over large distances and does not require any improvements in technology beyond the state of the art.

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Section: A Numerical Calculation Of the Photon Indistinguishabilitymentioning

confidence: 96%

An integrated quantum repeater at telecom wavelength with single atoms in optical fiber cavities

et al. 2016

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“…After frequency conversion, the photons are guided to the middle station with fibres of different lengths where an interferometric Bell-state measurement (BSM) swaps the entanglement to the atoms 6 , 10 . The fidelity of the BSM, and hence of the entanglement swapping protocol, is determined by the photons temporal, spectral and spatial indistinguishability 32 . This is optimized by different means.…”

Section: Quantum Network Linkmentioning

confidence: 99%

Entangling single atoms over 33 km telecom fibre

Leent

Bock

Fertig

et al. 2022

Nature

116

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Quantum networks promise to provide the infrastructure for many disruptive applications, such as efficient long-distance quantum communication and distributed quantum computing1,2. Central to these networks is the ability to distribute entanglement between distant nodes using photonic channels. Initially developed for quantum teleportation3,4 and loophole-free tests of Bell’s inequality5,6, recently, entanglement distribution has also been achieved over telecom fibres and analysed retrospectively7,8. Yet, to fully use entanglement over long-distance quantum network links it is mandatory to know it is available at the nodes before the entangled state decays. Here we demonstrate heralded entanglement between two independently trapped single rubidium atoms generated over fibre links with a length up to 33 km. For this, we generate atom–photon entanglement in two nodes located in buildings 400 m line-of-sight apart and to overcome high-attenuation losses in the fibres convert the photons to telecom wavelength using polarization-preserving quantum frequency conversion9. The long fibres guide the photons to a Bell-state measurement setup in which a successful photonic projection measurement heralds the entanglement of the atoms10. Our results show the feasibility of entanglement distribution over telecom fibre links useful, for example, for device-independent quantum key distribution11–13 and quantum repeater protocols. The presented work represents an important step towards the realization of large-scale quantum network links.

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“…After frequency conversion, the photons are guided to the middle station with fibres of different lengths where a Bell-state measurement (BSM) swaps the entanglement to the atoms 6,23 . The fidelity of the BSM, and hence of the entanglement swapping protocol, is determined by the photons temporal, spectral, and spatial indistinguishability 28 . This is optimized by different means, first, the photons impinge on a balanced, singlemode fibre beam splitter to guarantee a perfect spatial overlap.…”

Section: Quantum Network Link With Telecom Interfacesmentioning

confidence: 99%

Entangling single atoms over 33 km telecom fibre

van Leent,

Bock,

Fertig

et al. 2021

Preprint

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Heralded entanglement between distant quantum memories is the key resource for quantum networks. Based on quantum repeater protocols, these networks will facilitate efficient large-scale quantum communication and distributed quantum computing. However, despite vast efforts, long-distance fibre based network links have not been realized yet. Here we present results demonstrating heralded entanglement between two independent, remote single-atom quantum memories generated over fibre links with a total length up to 33 km. To overcome the attenuation losses in the long optical fibres of photons initially emitted by the Rubidium quantum memories, we employ polarization-preserving quantum frequency conversion to the low loss telecom band. The presented work represents a milestone towards the realization of efficient quantum network links.

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Towards high-fidelity interference of photons emitted by two remotely trapped Rb-87 atoms

Cited by 6 publications

References 14 publications

An integrated quantum repeater at telecom wavelength with single atoms in optical fiber cavities

An integrated quantum repeater at telecom wavelength with single atoms in optical fiber cavities

Entangling single atoms over 33 km telecom fibre

Entangling single atoms over 33 km telecom fibre

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