• DOI:10.1038/nphoton.2014.152
• Corpus ID: 10874278

On the experimental verification of quantum complexity in linear optics

@article{Carolan2013OnTE,
  title={On the experimental verification of quantum complexity in linear optics},
  author={Jacques Carolan and Jasmin D. A. Meinecke and Peter J. Shadbolt and Nicholas J. Russell and Nur Ismail and Kerstin Wörhoff and Terry Rudolph and Mark G. Thompson and Jeremy Lloyd O'Brien and Jonathan C. F. Matthews and Anthony Laing},
  journal={Nature Photonics},
  year={2013},
  volume={8},
  pages={621 - 626}
}

• J. Carolan, J. Meinecke, +8 authors A. Laing
• Published 12 November 2013
• Physics
• Nature Photonics

Quantum computers promise to solve certain problems that are forever intractable to classical computers. The first of these devices are likely to tackle bespoke problems suited to their own particular physical capabilities. Sampling the probability distribution from many bosons interfering quantum-mechanically is conjectured to be intractable to a classical computer but solvable with photons in linear optics. However, the complexity of this type of problem means its solution is mathematically unverifiable, so the task of establishing successful operation becomes one of gathering sufficiently convincing circumstantial or experimental evidence. Here, we develop scalable methods to experimentally establish correct operation for this class of computation, which we implement for three, four and five photons in integrated optical circuits, on Hilbert spaces of up to 50,000 dimensions. Our broad approach is practical for all quantum computational architectures where formal verification methods for quantum algorithms are either intractable or unknown. Scalable methods employing a random unitary chip and a quantum walk chip are developed to experimentally verify correct operation for large-scale boson sampling. Experimental analysis reveals that the resulting statistics of the output of a linear interferometer fed by indistinguishable single-photon states exhibits true non-classical characteristics.