A quantum network node with crossed optical fibre cavities

Brekenfeld, Manuel; Niemietz, Dominik; Christesen, Joseph D.; Rempe, Gerhard

doi:10.1038/s41567-020-0855-3

Cited by 81 publications

(86 citation statements)

References 39 publications

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“…The experiment starts with a two-second-long loading phase of a single atom into the crossing point of the two fibre-cavity modes (details in ref. 26 ). A magneto-optical trap with 87 Rb atoms is loaded approximately 10 mm above the fibres and is released such that the laser-cooled atoms fall towards the intracavity region.…”

Section: Methodsmentioning

confidence: 99%

“…Here, the applied laser fields are the same as described in ref. 26 , except we do not apply the final 4-μs-long π-polarized laser field used in that work. After optical pumping, the sequence starts with the NPQD scheme as reported in the main text.…”

Section: Methodsmentioning

confidence: 99%

“…However, interference requires prior knowledge about the pulse shape and arrival time and therefore restricts the range of possible applications. Finally, our previous work on heralded quantum memories 25 , 26 can, in combination with readout, be used to herald photonic qubits. But the single-photon herald signal is highly sensitive to losses and the system therefore has a small detection efficiency.…”

Section: Mainmentioning

confidence: 99%

“…Note that both fibre cavities are single-sided (for details, see ref. 26 ), so that the dominant escape channels for cavity photons are the two single-mode fibres.…”

Section: Mainmentioning

confidence: 99%

“…The first example (Fig. 4a ) consists of an atom–photon entanglement source 9 that sends photonic qubits to a heralded quantum memory 26 to generate sender–receiver entanglement. The plot shows the entanglement speed-up defined as the ratio of the mean entanglement generation time without the nondestructive detector to that with the nondestructive detector, , versus the channel length L .…”

Section: Mainmentioning

confidence: 99%

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Nondestructive detection of photonic qubits

Niemietz

Farrera

Langenfeld

et al. 2021

Nature

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One of the biggest challenges in experimental quantum information is to sustain the fragile superposition state of a qubit1. Long lifetimes can be achieved for material qubit carriers as memories2, at least in principle, but not for propagating photons that are rapidly lost by absorption, diffraction or scattering3. The loss problem can be mitigated with a nondestructive photonic qubit detector that heralds the photon without destroying the encoded qubit. Such a detector is envisioned to facilitate protocols in which distributed tasks depend on the successful dissemination of photonic qubits4,5, improve loss-sensitive qubit measurements6,7 and enable certain quantum key distribution attacks8. Here we demonstrate such a detector based on a single atom in two crossed fibre-based optical resonators, one for qubit-insensitive atom–photon coupling and the other for atomic-state detection9. We achieve a nondestructive detection efficiency upon qubit survival of 79 ± 3 per cent and a photon survival probability of 31 ± 1 per cent, and we preserve the qubit information with a fidelity of 96.2 ± 0.3 per cent. To illustrate the potential of our detector, we show that it can, with the current parameters, improve the rate and fidelity of long-distance entanglement and quantum state distribution compared to previous methods, provide resource optimization via qubit amplification and enable detection-loophole-free Bell tests.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Mainmentioning

confidence: 99%

“…Note that both fibre cavities are single-sided (for details, see ref. 26 ), so that the dominant escape channels for cavity photons are the two single-mode fibres.…”

Section: Mainmentioning

confidence: 99%

Section: Mainmentioning

confidence: 99%

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Nondestructive detection of photonic qubits

Niemietz

Farrera

Langenfeld

et al. 2021

Nature

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Quantum Plasmonics: Energy Transport Through Plasmonic Gap

2021

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scanning tunneling microscopy (STM), [5,6] atomic force microscopy (AFM), [7] and other techniques allowing resolution to be reduced to the atomic scale can help realize atomic-scale world exploration. This is the starting point of the nanotechnology era; since its inception, this technology has changed the nature of almost every human-made object. Six decades after Richard Feynman's lecture, we find that there is still plenty of room at the bottom, through the incorporation of nanophotonics. [8] To elucidate: quantum plasmonics has emerged as an attractive research field in new nanophotonics; research is underway to reveal and accurately describe the quantum nature of electrons at the bottom of extremely confined nano-or sub-nanometer scale materials, using light. [9,10] By exploring the quantum mechanical interactions of matter with light (in particular, using the coherent interactions between the plasmonic cavity and the material), [11][12][13][14][15][16][17][18] these efforts seek to establish new frontiers in information processing technology and to satisfy the everincreasing requirements for speed and capacity in quantum computing, quantum cryptography, and quantum metrology. They might also suggest research fields beyond this, involving the ultimate miniaturization of photonic components and the extreme limits of the light-matter interaction. These advantages may help solve some fundamental problems of electronics, such as those of bandwidth, frequency, and energy consumption. [19] In this review, we describe recent developments in the research of exotic materials capable of mediating quantum plasmonics and inducing quantum energy transport. We briefly provide classical and quantum descriptions of matter, from the bulk, nano, and cluster scales down to atomic matter, exploring the band structures via their optical responses. By considering a single nanoplasmonic material, we describe the theoretical and experimental findings pertaining to assembled nanoplasmonic structures, in the context of the plasmonic gap distance and the type of advanced functional material. The plasmonic gap herein refers to a nanometer or sub-nanometer gap that transports (couples, tunnels, exchanges, confines) electromagnetic energy between plasmonic resonators. Advanced functional materials within an extremely confined metallic resonator are described; these include air/vacuum, aliphatic and conjugated molecules, 2D materials, organic and inorganic materials with At the interfaces of metal and dielectric materials, strong light-matter interactions excite surface plasmons; this allows electromagnetic field confinement and enhancement on the sub-wavelength scale. Such phenomena have attracted considerable interest in the field of exotic material-based nanophotonic research, with potential applications including nonlinear spectroscopies, information processing, single-molecule sensing, organic-molecule devices, and plasmon chemistry. These innovative plasmonics-based technologies can meet the ever-increasing demands for speed and ca...

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Photonic Integrated Quantum Memory in Rare‐Earth Doped Solids

Zhou,

Liu,

et al. 2023

Laser & Photonics Reviews

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An optical quantum memory is a device that can store photonic quantum information and release it after a controlled time. It is an essential component for overcoming channel losses in large‐scale quantum networks. Optical quantum memories have been demonstrated with various physical systems including atomic gases, single atoms in optical cavities, and rare‐earth‐ion doped solids. Now, quantum memories are marching toward miniaturization and integration for large‐scale practical applications. Solid state systems stand as a natural choice due to the physical stability and ease of micro or nano fabrication using well‐established techniques. In the past decade, considerable efforts have been devoted to developing photonic integrated quantum memories, that is, quantum memories based on micro/nano‐photonic structures manufactured in solids. Remarkable performances have been achieved with integrated quantum memories, with the advantages of lower laser/electric power requirements, small volumes, large storage densities, and easy implementations. In this article, the basic concepts of optical quantum memories, the state‐of‐the‐art technologies for fabricating integrated quantum memories in rare‐earth ions doped crystals, and recent advances are introduced, and the roadmap for developing practically useful devices for applications in quantum networks is discussed.

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A quantum network node with crossed optical fibre cavities

Cited by 81 publications

References 39 publications

Nondestructive detection of photonic qubits

Nondestructive detection of photonic qubits

Quantum Plasmonics: Energy Transport Through Plasmonic Gap

Photonic Integrated Quantum Memory in Rare‐Earth Doped Solids

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