Abstract
The realization of a long-distance, distributed quantum network based on quantum memory nodes that are linked by photonic channels remains an outstanding challenge. We propose a quantum network node based on neutral alkali atoms coupled to nanophotonic crystal cavities that combines a long-lived memory qubit with a photonic interface at the telecom range, thereby enabling the long-distance distribution of entanglement over low loss optical fibers. We present a novel protocol for the generation of an atom–photon entangled state which uses telecom transitions between excited states of the alkali atoms. We analyze the realistic implementation of this protocol using rubidium and cesium atoms taking into account the full atomic level structure and properties of the nanophotonic crystal cavity. We find that a high fidelity entangled state can be generated with current technologies.
Highlights
Quantum networks have been envisioned as the underlying platform for revolutionizing technologies including secure communication [1, 2], distributed quantum computing [3, 4], and quantum enhanced metrology [5,6,7]
The realization of a long-distance, distributed quantum network based on quantum memory nodes that are linked by photonic channels remains an outstanding challenge
We propose a quantum network node based on neutral alkali atoms coupled to nanophotonic crystal cavities that combines a long-lived memory qubit with a photonic interface at the telecom range, thereby enabling the long-distance distribution of entanglement over low loss optical fibers
Summary
Quantum networks have been envisioned as the underlying platform for revolutionizing technologies including secure communication [1, 2], distributed quantum computing [3, 4], and quantum enhanced metrology [5,6,7]. While frequency conversion can be employed to shift emitted photons from the near-infrared and visible to the telecom range [13, 33], this process adds noise and has finite conversion efficiency It can limit both the rate of entanglement generation and the fidelity of the entangled states. We propose a fiber-based quantum network with individual nodes of neutral alkali atoms coupled to a nanophotonic crystal cavity (PCC) (see figure 1(a)) and a multilevel excitation protocol that yields emission in the telecom range. We show that this node is capable of generating a high fidelity atom–photon entangled state, which is the essential functionality required for distributing entanglement. We discuss the design and performance of a suitable telecom photonic crystal cavity and demonstrate the feasibility of creating a high fidelity atom–photon entangled state by analyzing the performance of the protocol for the full system
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