A hybrid quantum memory–enabled network at room temperature

Pang, Xiao-Ling; Yang, Ai Lin; Dou, Jian Peng; Li, Hang; Zhang, Chao Ni; Poem, Eilon; Saunders, D. J.; Tang, Hao; Nunn, Joshua; Walmsley, Ian A.; Jin, Xian

doi:10.1126/sciadv.aax1425

“…Various physical systems 8 such as atomic ensembles 2,4,9 and single quantum systems, including single atoms 10,11 , ions 12,13 and solid-state spins 14,15 have been proposed as nodes. The atomic-ensemble-based nodes, which were initially proposed in the Duan-Lukin-Cirac-Zoller (DLCZ) protocol 4 , are formed by quantum interface (QIs) that create quantum correlations between a spin wave (SW) and a photon via spontaneous Raman emissions (SREs) induced by a write pulse 2,[16][17][18][19][20][21][22][23][24][25][26][27][28][29] . The quantum correlations created via SREs form the basis of generating entanglement between a photonic qubit and a SW qubit 2,[30][31][32][33] .…”

mentioning

confidence: 99%

Long-lived and multiplexed atom-photon entanglement interface with feed-forward-controlled readouts

Wang

¹

,

Wang

²

,

Yan

³

et al. 2021

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Quantum interfaces (QIs) that generate entanglement between photonic and spin-wave (atomic memory) qubits are basic building block for quantum repeaters. Realizing ensemble-based repeaters in practice requires quantum memory providing long lifetimes and multimode capacity. Significant progress has been achieved on these separate goals. The remaining challenge is to combine the two attributes into a single QI. Here, by establishing spatial multimode, magnetic-field-insensitive and long-wavelength spin-wave storage in laser-cooled atoms inside a phase-passively-stabilized polarization interferometer, we constructed a multiplexed QI that stores up to three long-lived spin-wave qubits. Using a feed-forward-controlled system, we demonstrated that a multiplexed QI gives rise to a 3-fold increase in the atom–photon (photon–photon) entanglement-generation probability compared with single-mode QIs. For our multiplexed QI, the measured Bell parameter is 2.51±0.01 combined with a memory lifetime of up to 1 ms. This work represents a key step forward in realizing fiber-based long-distance quantum communications.

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“…Except for utilizing all matter-based quantum memory as quantum node, all-optical quantum memory can also act as quantum node. In 2020, X. L. Pang et al demonstrated room-temperature connection between atomic ensembles and an all-optical loop memory [228] by sending a write-out photon from the atoms to the optical loop memory.…”

Section: Quantum Network With Other Physical Systems and Hybrid Appro...mentioning

confidence: 99%

Towards real-world quantum networks: a review

Wei,

Jing,

Zhang

et al. 2022

Preprint

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Quantum networks play an extremely important role in quantum information science, with application to quantum communication, computation, metrology and fundamental tests. One of the key challenges for implementing a quantum network is to distribute entangled flying qubits to spatially separated nodes, at which quantum interfaces or transducers map the entanglement onto stationary qubits. The stationary qubits at the separated nodes constitute quantum memories realized in matter while the flying qubits constitute quantum channels realized in photons. Dedicated efforts around the world for more than twenty years have resulted in both major theoretical and experimental progress towards entangling quantum nodes and ultimately building a global quantum network. Here, we review the development of quantum networks and the experimental progress over the past two decades leading to the current state of the art for generating entanglement of quantum nodes based on various physical systems such as single atoms, cold atomic ensembles, trapped ions, diamonds with Nitrogen-Vacancy centers, solid-state host doped with rare-earth ions, etc. Along the way we discuss the merits and compare the potential of each of these systems towards realizing a quantum network.

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“…When it comes to quantum storage time, the main challenge with room-temperature atomic ensembles is their thermal motion and/or collisional decoherence. Due to those limitations the DLCZ-type single-photon sources in room-temperature vapors have been up to now limited in their on-demand retrieval time to a few microseconds 22 – 24 . Another limitation on the performance of DLCZ-type sources has been the quantum readout noise 25 .…”

Section: Introductionmentioning

confidence: 99%

Room-temperature single-photon source with near-millisecond built-in memory

Dideriksen

¹

,

Schmieg

²

,

Zugenmaier

³

et al. 2021

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Non-classical photon sources are a crucial resource for distributed quantum networks. Photons generated from matter systems with memory capability are particularly promising, as they can be integrated into a network where each source is used on-demand. Among all kinds of solid state and atomic quantum memories, room-temperature atomic vapours are especially attractive due to their robustness and potential scalability. To-date room-temperature photon sources have been limited either in their memory time or the purity of the photonic state. Here we demonstrate a single-photon source based on room-temperature memory. Following heralded loading of the memory, a single photon is retrieved from it after a variable storage time. The single-photon character of the retrieved field is validated by the strong suppression of the two-photon component with antibunching as low as $${g}_{{\rm{RR| W = 1}}}^{(2)}=0.20\pm 0.07$$ g RR∣W=1 ( 2 ) = 0.20 ± 0.07 . Non-classical correlations between the heralding and the retrieved photons are maintained for up to $${\tau }_{{\rm{NC}}}^{{\mathcal{R}}}=(0.68\pm 0.08)\ {\rm{ms}}$$ τ NC R = ( 0.68 ± 0.08 ) ms , more than two orders of magnitude longer than previously demonstrated with other room-temperature systems. Correlations sufficient for violating Bell inequalities exist for up to τBI = (0.15 ± 0.03) ms.

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A hybrid quantum memory–enabled network at room temperature

Cited by 43 publications

References 49 publications

Long-lived and multiplexed atom-photon entanglement interface with feed-forward-controlled readouts

Long-lived and multiplexed atom-photon entanglement interface with feed-forward-controlled readouts

Towards real-world quantum networks: a review

Room-temperature single-photon source with near-millisecond built-in memory

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