Mean Field Approximation for Identical Bosons on the Complete Graph

Abstract: Non-linear dynamics in the quantum random walk setting have been shown to enable conditional speedup of Grover's algorithm. We examine the mean field approximation required for the use of the Gross-Pitaevskii equation on identical bosons evolving on the complete graph. We show that the states of such systems are parameterized by the basis of Young diagrams and determine their one- and two-party marginals. We find that isolated particles are required for good agreement with the mean field approximation, proving that without isolated particles the matrix fidelity agreement is bounded from above by $1/2$.