Quantum Simulation and the Chess-Queens


PI Wolfgang Lechner and his team at the University of Innsbruck published a paper on solving the "Queen problem" in chess!

The N-queens problem is to find the position of N queens on an N by N chessboard such that no queens attack each other. The excluded diagonals N-queens problem is a variation where queens cannot be placed on some predefined fields along diagonals. This variation is proven NP-complete and the parameter regime to generate hard instances that are intractable with current classical algorithms is known.

We propose a special purpose quantum simulator that implements the excluded diagonals N-queens completion problem using atoms in an optical lattice and cavity-mediated long-range interactions. Our implementation has no overhead from the embedding allowing to directly probe for a possible quantum advantage in near term devices for optimization problems.

Read the full article here.

A Quantum N-Queens Solver
V. Torggler, P. Aumann, H. Ritsch, W. Lechner
Quantum 3, 149 (2019).


Popular media also covered the question and results of the paper!
Read them here (in German):



© Uni Innsbruck