Computing Permanents for Boson Sampling on Tianhe-2 Supercomputer.

Boson sampling, a specific quantum computation problem, is widely regarded to be one of the most achievable fields in which quantum machine will outperform the most powerful classical computer in the near term, although up to now no upper-bound of how fast the classical computers can compute matrix permanents, core problem of Boson sampling, has been reported. Here we test the computing of the matrix permanent on Tianhe-2, a supercomputer retaining its position as the worldu0027s No. 1 system for six times since June 2013. We arrived at the time (about 77.41~112.44 minutes) to compute the permanent of a $50times 50$ matrix in an acceptable precision. In addition, we have found that Ryseru0027s algorithm will produce an unacceptable error with the increase of problem scale, compared to Balasubramanian-Bax/Franklin-Glynnu0027s algorithm in the same complexity. The precision issue suggests carefully check in future research of Boson sampling, and comprehensive comparison between quantum computer and classical computer.