A boson sampler implements a restricted model of quantum computing. It is
defined by the ability to sample from the distribution resulting from the
interference of identical bosons propagating according to programmable,
non-interacting dynamics. Here, we demonstrate a new combination of tools for
implementing boson sampling using ultracold atoms in a two-dimensional,
tunnel-coupled optical lattice. These tools include fast and programmable
preparation of large ensembles of nearly identical bosonic atoms
(99.5β1.6+0.5β% indistinguishability) by means of rearrangement with
optical tweezers and high-fidelity optical cooling, propagation for variable
evolution time in the lattice with low loss (5.0(2)%, independent of
evolution time), and high fidelity detection of the atom positions after their
evolution (typically 99.8(1)%). With this system, we study specific
instances of boson sampling involving up to 180 atoms distributed among βΌ1000 sites in the lattice. Direct verification of a given boson sampling
distribution is not feasible in this regime. Instead, we introduce and perform
targeted tests to determine the indistinguishability of the prepared atoms, to
characterize the applied family of single particle unitaries, and to observe
expected bunching features due to interference for a large range of atom
numbers. When extended to interacting systems, our work demonstrates the core
capabilities required to directly assemble ground and excited states in
simulations of various Hubbard models.Comment: 20 pages, 7 figures (main text and methods); 8 pages, 2 figures
(supplemental materials