On-Demand Semiconductor Source of Entangled Photons Which Simultaneously Has High Fidelity, Efficiency, and Indistinguishability

Wang, Hui; Hu, Hai; Chung, Tung Hsun; Qin, Jian; Yang, Xiaoxia; Li, J.-P.; Liu, Run-Ze; Zhong, Han-Sen; He, Yu; Ding, Xing; Deng, Youjin; Dai, Qing; Huo, Yongheng; Höfling, Sven; Lu, Chao‐Yang; Pan, Jian-Wei

doi:10.1103/physrevlett.122.113602

Cited by 276 publications

(181 citation statements)

References 66 publications

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“…The spectral resonance of the bullseye cavity is strongly sensitive to the radius of the central disk and the grating period. It was previously shown that a 1-nm change of the central disk radius (grating period) causes a 1.14 nm (0.25 nm) shift of the cavity mode 46 . Thus, a 1% ellipticity, which is 23 times smaller than that of our elliptical micropillar, is sufficient to induce a suitable cavity mode splitting.…”

Section: Elliptical Bragg Gratingmentioning

confidence: 99%

Towards optimal single-photon sources from polarized microcavities

et al. 2019

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An optimal single-photon source should deterministically deliver one and only one photon at a time, with no trade-off between the source's efficiency and the photon indistinguishability. However, all reported solid-state sources of indistinguishable single photons had to rely on polarization filtering which reduced the efficiency by 50%, which fundamentally limited the scaling of photonic quantum technologies. Here, we overcome this final long-standing challenge by coherently driving quantum dots deterministically coupled to polarization-selective Purcell microcavities-two examples are narrowband, elliptical micropillars and broadband, elliptical Bragg gratings. A polarization-orthogonal excitation-collection scheme is designed to minimize the polarization-filtering loss under resonant excitation. We demonstrate a polarized single-photon efficiency of 0.60(2), a single-photon purity of 0.991(3), and an indistinguishability of 0.973(5). Our work provides promising solutions for truly optimal single-photon sources combining near-unity indistinguishability and near-unity system efficiency simultaneously.Single photons are appealing candidates for quantum communications 1,2 , quantumenhanced metrology 3,4 and quantum computing 5,6 . In view of the quantum information applications, the single photons are required to be controllably prepared with a high efficiency into a given quantum state. Specifically, the single photons should possess the same polarization, spatial mode, and transform-limited spectro-temporal profile for a high-visibility Hong-Ou-Mandel-type quantum interference 1,7 .Self-assembled quantum dots show so far the highest quantum efficiency among solid-state quantum emitters and thus can potentially serve as an ideal single-photon source 8-15 . There has been encouraging progress in recent years in developing highperformance single-photon sources 11 . Pulsed resonant excitation on single quantum dots has been developed to eliminate dephasing and time jitter, which created single photons with near-unity indistinguishability 15 . Further, by combining the resonant excitation with Purcell-enhanced micropillar 16,17 or photonic crystals 18,19 , the generated transform-limited 20,21 single photons have been efficiently extracted out of the bulk and funneled into a single mode at far field. Despite the recent progress 16-22 , the experimentally achieved polarized-single-photon efficiency (defined as the number of single-polarized photons extracted from the bulk semiconductor and collected by the first lens per pumping pulse) is ~33% in ref. 16 and ~15% in ref. 17, still fell short of the minimally required efficiency of 50% for boson sampling to show computational advantage to classical algorithms 23 , and was below the efficiency threshold of 67% for photon-loss-tolerant encoding in cluster-state models of optical quantum computing 24 . It should be noted that a <50% single-photon efficiency would render nearly all linear optical quantum computing schemes 1,5 not scalable.The indistinguishable single-photon...

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Section: Elliptical Bragg Gratingmentioning

confidence: 99%

Towards optimal single-photon sources from polarized microcavities

et al. 2019

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“…the Sirius, within currently available technologies. With a single photon source of better purity [34][35][36] , one can tolerate even feebler starlight and shorten the data accumulation time significantly (see Sec. V of Supplemental Material).…”

Section:  mentioning

confidence: 99%

Quantum Interference between Light Sources Separated by 150 Million Kilometers

et al. 2019

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We report an experiment to test quantum interference, entanglement and nonlocality using two dissimilar photon sources, the Sun and a semiconductor quantum dot on the Earth, which are separated by ~150 million kilometers. By making the otherwise vastly distinct photons indistinguishable in all degrees of freedom, we observe time-resolved two-photon quantum interference with a raw visibility of 0.796(17), well above the 0.5 classical limit, providing the first evidence of quantum nature of thermal light. Further, using the photons with no common history, we demonstrate post-selected two-photon entanglement with a state fidelity of 0.826(24), and a violation of Bell's inequality by 2.20(6). The experiment can be further extended to a larger scale using photons from distant stars, and open a new route to quantum optics experiments at an astronomical scale.Can any two photons in the Universe, no matter how distantly and independently they originate from, show quantum interference and entanglement? According to quantum theory, when two quantum-mechanically indistinguishable single photons impinge upon a 50/50 beam splitter, they bunch together out of the same output port due to bosonic statistics. The classical picture of electromagnetic fields failed in understanding the interference of two photons from independent sources with a visibility better than 50% 1-4 , which can be explained by quantum interference of the probability amplitudes of the twophoton events 5 . This effect, also known as Hong-Ou-Mandel (HOM) two-photon interference 6 , poses a strong conceptual challenge to the celebrated statement by Dirac that "Each photon then interferes only with itself. Interference between different photons never occurs" 7 .

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“…To date, these systems are constrained to cryogenic conditions where interactions with the solid-state environment, in particular the thermal bath of lattice phonons, are adequately suppressed. Even at very low temperatures, only a few systems, such as III-V quantum dots (QDs) [8][9][10], color centers in solids [11][12][13] as well as single molecules [14], have shown FT limited spectral lines. Here we report a solid-state SPE in a two-dimensional (2D) material -hexagonal boron nitride (hBN) -that exhibits FT limited lines at room temperature under resonant excitation (see figure 1(d)).…”

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confidence: 99%

Solid-state single photon source with Fourier transform limited lines at room temperature

et al. 2020

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Solid state single photon sources with Fourier Transform (FT) limited lines are among the most crucial constituents of photonic quantum technologies and have been accordingly the focus of intensive research over the last several decades. However, so far, solid state systems have only exhibited FT limited lines at cryogenic temperatures due to strong interactions with the thermal bath of lattice phonons. In this work, we report a solid state source that exhibits FT limited lines measured in photo luminescence excitation (sub 100 MHz linewidths) from 3K-300K. The studied source is a color center in the two-dimensional hexagonal boron nitride and we propose that the center's decoupling from phonons is a fundamental consequence of material's low dimensionality. While the center's luminescence lines exhibit spectral diffusion, we identify the likely source of the diffusion and propose to mitigate it via dynamic spectral tuning. The discovery of FT-limited lines at room temperature, which once the spectral diffusion is controlled, will also yield FT-limited emission. Our work motivates a significant advance towards room temperature photonic quantum technologies and a new research direction in the remarkable fundamental properties of two-dimensional materials. DOI: XXXXXXXXFuture applications of quantum technology rely on compact and scalable quantum platforms. An essential building block for photonic quantum technologies, including quantum communication networks, quantum sensors and distributed quantum networks, are single photon emitters (SPEs) [1][2][3][4]. Coherent photon absorption and emission is a fundamental prerequisite to ensure, for example, coherent read and write of quantum information in various quantum protocols. Perfect coherence is achieved when all incoherent processes arising from interactions with the environment are suppressed. Once suppressed, the spectral line of an SPE matches the Fourier Transform of its excited state decay. This so-called Fourier Transform (FT) limit can be achieved at present with cold atomic ensembles [5], Doppler-broadened atomic ensembles [6] and single cold atoms [7], enabling single photon absorption and generation with high efficiency. However, cold atoms are limited in their photon absorption and generation rate and require complex apparatus for atom trapping and cooling in ultra-high vacuum conditions. All of which is challenging to scale. To achieve scaling via a different approach, various solid state quantum systems have been thoroughly investigated as SPEs. To date, these systems are constrained to cryogenic conditions where interactions with the solid-state environment, in particular the thermal bath of lattice phonons, are adequately suppressed. Even at very low temperatures, only a few systems, such as III-V quantum dots (QDs) [8][9][10], color centers in solids [11][12][13] as well as single molecules [14], have shown FT limited spectral lines. Here we report a solid-state SPE in a two-dimensional (2D) material -hexagonal boron nitride (hBN) -that exhibits FT l...

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On-Demand Semiconductor Source of Entangled Photons Which Simultaneously Has High Fidelity, Efficiency, and Indistinguishability

Cited by 276 publications

References 66 publications

Towards optimal single-photon sources from polarized microcavities

Towards optimal single-photon sources from polarized microcavities

Quantum Interference between Light Sources Separated by 150 Million Kilometers

Solid-state single photon source with Fourier transform limited lines at room temperature

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