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The DOI matches its Crossref record; 59 of the 59 references it cites were found in a registry or an index; none of the 18 sources its claims cite is checked for support yet.

12-Photon Entanglement and Scalable Scattershot Boson Sampling with Optimal Entangled-Photon Pairs from Parametric Down-Conversion

Open access
Zhong, Han-Sen, Li, Yuan, Li, Wei, Peng, Li-Chao, Su, Zu-En, Hu, Yi, He, Yu-Ming, Ding, Xing, Zhang, Weijun, Li, Hao, Zhang, Lu, Wang, Zhen, You, Lixing, Wang, Xi-Lin, Jiang, Xiao, Li, Li, Chen, Yu-Ao, Liu, Nai-Le, Lu, Chao-Yang, Pan, Jian-Wei·2018·Physical Review Letters
DOI 10.1103/physrevlett.121.250505
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Abstract

Entangled-photon sources with simultaneously near-unity heralding efficiency and indistinguishability are the fundamental elements for scalable photonic quantum technologies. We design and realize a degenerate telecommunication wavelength entangled-photon source from an ultrafast pulsed laser pumped spontaneous parametric down-conversion (SPDC), which shows simultaneously 97% heralding efficiency and 96% indistinguishability between independent single photons without narrow-band filtering. Such a beamlike and frequency-uncorrelated SPDC source allows generation of the first 12-photon genuine entanglement with a state fidelity of 0.572±0.024. We further demonstrate a blueprint of scalable scattershot boson sampling using 12 SPDC sources and a 12×12 mode interferometer for three-, four-, and five-boson sampling, which yields count rates more than 4 orders of magnitude higher than all previous SPDC experiments.

Overview

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TL;DR

The paper reports an optimized ultrafast-pumped SPDC entangled-photon source with simultaneously near-unity heralding efficiency and indistinguishability, enabling the first 12-photon genuine entanglement and a scalable scattershot boson sampling blueprint. Using 12 SPDC sources and a 12×12-mode interferometer, it demonstrates three-, four-, and five-boson sampling with multi-photon count rates more than four orders of magnitude higher than previous SPDC experiments.

Key findings

  • The source achieved ~97% corrected heralding efficiency and ~96% indistinguishability between independent single photons; Hong-Ou-Mandel interference showed a raw visibility of 0.962 ± 0.011, spectral purity was 0.99, and Bell-state visibility was above 0.997.
  • The first 12-photon genuine entanglement was generated with population P = 0.732 ± 0.024, coherence C = 0.419 ± 0.041, and state fidelity reported as 0.572 ± 0.024 in the abstract (0.576 ± 0.024 in the main text), exceeding the 0.5 threshold by more than 3 standard deviations.
  • Scattershot boson sampling with 12 SPDC sources and a 12×12-mode interferometer measured three-, four-, and five-photon sampling rates of 3.9 kHz, 44 Hz, and 0.3 Hz, respectively; the 3-boson sampling gave similarity 0.982 ± 0.004 and distance 0.122 ± 0.018.
  • The 3.9 kHz three-photon count rate is more than four orders of magnitude higher than the best previous SPDC-based boson sampling experiments and comparable to state-of-the-art quantum-dot single-photon work.

Methods

  • The entangled-photon source used beam-like type-II SPDC in a 6.3-mm BBO crystal pumped by a 775-nm pulsed laser with 5.5-nm bandwidth and 80-MHz repetition, generating photon pairs around 1550 nm; YVO4 beam displacers, half-wave plates, dispersion-compensating prisms, 30-nm bandpass filters, and superconducting nanowire single-photon detectors with ~75% average efficiency were used.
  • For 12-photon entanglement, six BBO crystals produced six entangled pairs; one photon from each pair was combined on five polarization beam splitters, and 12-photon coincidences were post-selected and measured with wave plates, PBSs, and 24 SNSPDs at 1.8 W pump power and 0.55-mm focal waist, giving a 2.0 MHz two-photon rate and about one 12-photon coincidence per hour.
  • For scattershot boson sampling, 12 SPDC sources fed a 12×12-mode interferometer encoded in spatial and polarization modes; idler photons heralded signal photons, and the experiment used a 0.8-mm pump waist and 0.5 MHz two-photon count rate, with similarity/distance metrics and likelihood ratio tests against a distinguishable-photon hypothesis.

Limitations

  • The paper states that scaling to larger photon numbers is prohibited by the intrinsically probabilistic generation of entangled photon pairs in SPDC, which would require multiplexing.
  • The paper states that similarity/distance characterization is not scalable to larger photon numbers; for four- and five-boson sampling the input-output combinations reach 495×495 and 792×792, making counting events extremely scarce, so a likelihood ratio test was used instead.
  • The paper notes that the slight deviation of the measured HOM visibility from the predicted 0.99 could be caused by residual dispersion of the pump laser; the text also makes evident that the 12-photon coincidence rate was about one per hour and the five-boson sampling rate was 0.3 Hz.

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Integrity signals

Registry

Crossref · 10.1103/physrevlett.121.250505

Cites

59 of 59 references verified0 citation errors · 0 not checkable

Statistics

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Verification

Claims the paper makes

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Show all 31 claims

  • It may state two separate claims as one. 6
  • Probably not a substantial claim. 5
11 of 11

  • The paper relies on this without support.

    Near-unity heralding efficiency and indistinguishability are fundamental requirements for scalable photonic quantum technologies.

    “Entangled photon sources with simultaneously near-unity heralding efficiency and indistinguishability are the fundamental elements for scalable photonic quantum technologies.”

  • The paper relies on this without support.

    The lack of a perfect entangled-photon source is the main reason scalable multi-photon entanglement remained challenging.

    “Yet, a more scalable implementation remained challenging, largely to the lack of a perfect entangled-photon source produced by ultrafast laser pumped SPDC where the photonic entanglement fidelity, the collection efficiency, and the indistinguishability between independent photons are simultaneously engineered to close to unity.”

  • The paper relies on this without support.

    The simultaneous combination of near-unity entanglement fidelity, indistinguishability, and collection efficiency remained an outstanding goal before this work.

    “There has been important progress in preparing heralded single photons in frequencyuncorrelated pure quantum state [42][43][44], yet the simultaneous combination of nearunity entanglement fidelity, indistinguishability, and collection efficiency remained an outstanding goal.”
3 of 3

Claims other papers make about this one

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Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Hong-Ou-Mandel citation points to the wrong reference

    Minor

    The text cites reference 47 for Hong-Ou-Mandel interference, but the bibliography lists the Hong, Ou, and Mandel paper as reference 46; reference 47 is a different paper.

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  1. 10.4086/toc.2013.v009a004 · DOI

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Metadata

Authors
Zhong, H.-S., Li, Y., Li, W., Peng, L.-C., Su, Z.-E., Hu, Y., He, Y.-M., Ding, X., Zhang, W., Li, H., Zhang, L., Wang, Z., You, L., Wang, X.-L., Jiang, X., Li, L., Chen, Y.-A., Liu, N.-L., Lu, C.-Y., & Pan, J.-W.
Affiliations
  • University of Science and Technology of China (CN)
  • Chinese Academy of Sciences (CN)
ORCID
Venue
Physical Review Letters
Publisher
American Physical Society (APS)
Published
2018-12-21
Volume
121
Issue
25
Pages
250505-250505
ISSN
  • 0031-9007 (ISSN-L)
  • 1079-7114
DOI
10.1103/physrevlett.121.250505
OpenAlex
W2896439086
Cited by
432
References
59
Citations by year
2026: 45 · 2025: 54 · 2024: 60 · 2023: 56 · 2022: 58 · 2021: 59 · 2020: 62 · 2019: 35 · 2018: 3
FWCI
18.86
Type
journal article
Language
en
Open access
Licence
link.aps.org/licenses/aps-default-license (vor)
Locations
  • Physical Review Letters (publishedVersion)
  • PubMed (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • Figshare (submittedVersion, cc-by)
  • arXiv (Cornell University)
  • Bulletin of the American Physical Society
Funders
  • National Natural Science Foundation of China (91836303)
  • Chinese Academy of Sciences
  • National Fundamental Research Program
Topics
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Quantum Information and Cryptography
  • Physical Sciences › Computer Science › Artificial Intelligence › Quantum Computing Algorithms and Architecture
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Quantum optics and atomic interactions
Keywords
entangled photon pairs, spontaneous parametric down-conversion, heralding efficiency, photon indistinguishability, photonic quantum technologies

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