2003/10/21 by Magniez, Frederic, Santha, Miklos, Szegedy, Mario · 6 citations
#FOS: Physical sciences #Quantum Physics (quant-ph)
paper · doi:10.48550/arxiv.quant-ph/0310134
We present two new quantum algorithms that either find a triangle (a copy of K3) in an undirected graph G on n nodes, or reject if G is triangle free. The first algorithm uses combinatorial ideas with Grover Search and makes O(n10/7) queries. The second algorithm uses O(n13/10) queries, and it is based on a design concept of Ambainis~\citeamb04 that incorporates the benefits of quantum walks into Grover search~\citegro96. The first algorithm uses only O(log n) qubits in its quantum subroutines, whereas the second one uses O(n) qubits. The Triangle Problem was first treated in~\citebdhhmsw01, where an algorithm with O(n+√(nm)) query complexity was presented, where m is the number of edges of G.