Fig. 1: Boson Sampling in a 3D continuous-coupling integrated device.
From: Reconfigurable continuously-coupled 3D photonic circuit for Boson Sampling experiments
a Boson Sampling (BS) and the most recent variants, (b) Scattershot Boson Sampling (SBS) and (c) Gaussian Boson Sampling GBS). The corresponding computational problems require sampling from the output distribution using different input quantum states of light, such as Fock states in BS, two-mode squeezed vacuum states in SBS and single-mode squeezed vacuum states in GBS. The common element among the schemes is the optical random circuit, described by the unitary evolution U. d The most widely adopted decomposition of the operator U is via a network of beamsplitters, with splitting ratios Sij, and phase-shifts ϕi (left); an alternative implementation exploits continuous-coupling by evanescent waves among waveguides (right) depending on the coupling coefficients cij and the propagation constants ki, where both may vary along the direction z. e Overview of the reconfigurable 3D integrated photonic chip, realized through the femtosecond laser writing technique. The device is composed by 32 optical-modes arranged in a triangular lattice, as showed in the inset reporting the transverse section of the sample. In red we have highlighted the input modes employed in the 3- and 4-photon experiment. The transformation U is controlled by the 16 resistors fabricated on top of the glass sample. The second inset shows the top view of the electrical circuits that controls the currents Ii applied to the resistors.
