Toward Scalable Boson Sampling with Photon Loss

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Toward Scalable Boson Sampling with Photon Loss

Hui Wang, Wei Li, Xiao Jiang, Y.-M. He, Y.-H. Li, X. Ding, M.-C. Chen, J. Qin, C.-Z. Peng, C. Schneider, M. Kamp, W.-J. Zhang, H. Li, L.-X. You, Z. Wang, J. P. Dowling, S. Höfling, Chao-Yang Lu, and Jian-Wei Pan

Phys. Rev. Lett. 120, 230502 – Published 6 June 2018

See Viewpoint: Lost Photons Won’t Derail Quantum Sampling

Abstract

Boson sampling is a well-defined task that is strongly believed to be intractable for classical computers, but can be efficiently solved by a specific quantum simulator. However, an outstanding problem for large-scale experimental boson sampling is the scalability. Here we report an experiment on boson sampling with photon loss, and demonstrate that boson sampling with a few photons lost can increase the sampling rate. Our experiment uses a quantum-dot-micropillar single-photon source demultiplexed into up to seven input ports of a $16 \times 16$ mode ultralow-loss photonic circuit, and we detect three-, four- and fivefold coincidence counts. We implement and validate lossy boson sampling with one and two photons lost, and obtain sampling rates of 187, 13.6, and 0.78 kHz for five-, six-, and seven-photon boson sampling with two photons lost, which is 9.4, 13.9, and 18.0 times faster than the standard boson sampling, respectively. Our experiment shows an approach to significantly enhance the sampling rate of multiphoton boson sampling.

Received 16 January 2018

DOI:https://doi.org/10.1103/PhysRevLett.120.230502

Physics Subject Headings (PhySH)

Boson sampling Quantum computation Quantum information architectures & platforms Quantum optics Quantum simulation

Quantum Information, Science & TechnologyAtomic, Molecular & Optical

Viewpoint

Lost Photons Won’t Derail Quantum Sampling

Published 6 June 2018

A photon-based method for demonstrating the advantage of quantum over classical machines can handle photon loss, facilitating experiments.

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Authors & Affiliations

Hui Wang^1,2,3, Wei Li^1,2,3, Xiao Jiang^1,2,3, Y.-M. He^1,2,3, Y.-H. Li^1,2,3, X. Ding^1,2,3, M.-C. Chen^1,2,3, J. Qin^1,2,3, C.-Z. Peng^1,2,3, C. Schneider⁴, M. Kamp⁴, W.-J. Zhang⁵, H. Li⁵, L.-X. You⁵, Z. Wang⁵, J. P. Dowling^6,7, S. Höfling^1,4,8, Chao-Yang Lu^1,2,3,*, and Jian-Wei Pan^1,2,3,†

¹Shanghai Branch, National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Shanghai 201315, China
²CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
³CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
⁴Technische Physik, Physikalisches Instität and Wilhelm Conrad Röntgen-Center for Complex Material Systems, Universitat Würzburg, Am Hubland, D-97074 Wüzburg, Germany
⁵State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China
⁶Hearne Institute for Theoretical Physics and Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
⁷NYU-ECNU Institute of Physics at NYU Shanghai, Shanghai 200062, China
⁸SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom

^*cylu@ustc.edu.cn
^†pan@ustc.edu.cn

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Vol. 120, Iss. 23 — 8 June 2018

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Images

Figure 1
(a) Experimental setup for lossy boson sampling. The setup contains four parts. The first part is a single-photon source from a quantum-dot micropillar. It is placed inside a 4.2 K cryostat, and a confocal microscopy is used to excite the quantum dot and collect its resonance fluorescence. The second part is six cascaded demultiplexers that separate the single photon stream into seven different spatial modes. Seven single-mode fibers with different lengths are used to compensate the time delay among seven different modes. The third part is the ultralow-loss photonic network; the demultiplexed single photons are injected into a $16 \times 16$ mode square-shaped photonic network, which contains 113 beam splitters and 14 mirrors. The last part is the detection; 13 superconducting nanowire single-photon detectors and 3 silicon-based avalanche detectors are used to detect photons, and a homemade coincidence-count unit registers all no-collision events (not shown). (b) The equivalent photonic circuit of our $16 \times 16$ mode interferometer, which is fully connected and has a transmission rate above 99%. (c) Enlarged ultralow-loss photonic network with a size of $50.91 mm \times 45.25 mm \times 4.00 mm$ .
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Figure 2
Experimental results for four-, five-, and six-photon boson sampling with one photon lost. The upper part of each graph are the experimental results, and the bottom part are the theoretical results, given by calculating permanents. All no-collision output combinations are denoted by ${i, j, \dots}$ where $i$ , $j$ , is the $i$ th, $j$ th, $\dots$ output port. There are 560, 1820, and 4368 output combinations for the four- (a), five- (b), and six-photon (c) boson sampling with one photon lost; the measured distances are 0.085(1), 0.106(2), and 0.201(3), and measured similarities are 0.994(1), 0.989(2), and 0.960(4), respectively.
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Figure 3
Validation of lossy boson sampling. (a) Extended likelihood ratio test to discriminate experimental data from a distinguishable sampler. (b) Application of extended RNE test to exclude the uniform distribution. The solid lines in (a) and (b) are tests applied on experimental data, and the dotted lines in (a) and (b) are tests applied on simulated data generated from a distinguishable sampler and a uniform sampler, respectively. The increasing difference between them indicates that experimental data are highly likely from a genuine boson sampler.
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Figure 4
(a) The count rate comparison between experimental data and theoretical predictions. The excellent matches show that lossy boson sampling will have an exponential speed-up over the standard scenario by a factor of $(\binom{n + k}{n})$ . (b) The sampling rate of a 50-photon boson sampling when the number of lost photons increase from zero to five. Note that the assumed parameters of efficiency are 0.8 for single-photon sources, 0.9 for interferometer, and 0.9 for single-photon detectors, respectively. Allowing two photons lost will make this experiment feasible, while it is not realistic to perform a standard boson sampling experiment with the same efficiency parameters. (c) Ascending ordered distributions of three-photon standard boson sampling (red), five-photon boson sampling with two photons lost (black), and seven-photon boson sampling with four photons lost (blue). If more photons are lost, the distribution will be closer to uniform distribution (pink).
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