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Integrated multimode interferometers with arbitrary designs for photonic boson sampling


The evolution of bosons undergoing arbitrary linear unitary transformations quickly becomes hard to predict using classical computers as we increase the number of particles and modes. Photons propagating in a multiport interferometer naturally solve this so-called boson sampling problem1, thereby motivating the development of technologies that enable precise control of multiphoton interference in large interferometers2,3,4. Here, we use novel three-dimensional manufacturing techniques to achieve simultaneous control of all the parameters describing an arbitrary interferometer. We implement a small instance of the boson sampling problem by studying three-photon interference in a five-mode integrated interferometer, confirming the quantum-mechanical predictions. Scaled-up versions of this set-up are a promising way to demonstrate the computational advantage of quantum systems over classical computers. The possibility of implementing arbitrary linear-optical interferometers may also find applications in high-precision measurements and quantum communication5.

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Figure 1: Layout of multimode interferometers.
Figure 2: Independent control of the phase shift and transmission at each directional coupler.
Figure 3: Experimental set-up for characterization of the chip.
Figure 4: Experimental results.


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This work was supported by the ERC-Starting Grant 3D-QUEST (3D-Quantum Integrated Optical Simulation; grant agreement no. 307783): D.B. and E.G. acknowledge support from the Brazilian National Institute for Science and Technology of Quantum Information (INCT-IQ/CNPq). The authors acknowledge support from G. Milani in assessing the data acquisition system.

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Authors and Affiliations



A.C., R.O., R.R., D.B., E.G., N.S., C.V., P.M. and F.S. conceived the experimental approach for hard-to-simulate experiments with integrated photonics. A.C., R.O. and R.R. developed the technique for three-dimensional circuits, and fabricated and characterized the integrated devices using classical optics. N.S., C.V., E.M., P.M. and F.S. carried out the quantum experiments. D.B., E.G., N.S., C.V., E.M. and F.S. elaborated the data. All authors discussed the experimental implementation and results, and contributed to writing the paper.

Corresponding authors

Correspondence to Roberto Osellame, Ernesto F. Galvão or Fabio Sciarrino.

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The authors declare no competing financial interests.

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Crespi, A., Osellame, R., Ramponi, R. et al. Integrated multimode interferometers with arbitrary designs for photonic boson sampling. Nature Photon 7, 545–549 (2013).

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