Integrated multimode interferometers with arbitrary designs for photonic boson sampling

• Published in: Nature photonics Vol. 7; no. 7; pp. 545 - 549
• Main Authors: Crespi, Andrea, Osellame, Roberto, Ramponi, Roberta, Brod, Daniel J., Galvão, Ernesto F., Spagnolo, Nicolò, Vitelli, Chiara, Maiorino, Enrico, Mataloni, Paolo, Sciarrino, Fabio
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-07-2013; Nature Publishing Group
• Subjects: Applied and Technical Physics; Bosons; Evolution; Interference; Interferometers; letter; Photonics; Physics; Quantum Physics; Sampling; Three dimensional; Transformations
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/nphoton.2013.112

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 problem
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, thereby motivating the development of technologies that enable precise control of multiphoton interference in large interferometers
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,
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,
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. 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 communication
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.
The boson-sampling problem was demonstrated by studying three-photon interference in a five-mode integrated interferometer containing three-dimensional S-bent waveguides. Three single photons were input into the interferometer and the probability ratios of all events were measured. The results agree with quantum mechanical predictions for three-photon interference.