Expansion Testing using Quantum Fast-Forwarding and Seed Sets

Quantum 4, 323 (2020).

https://doi.org/10.22331/q-2020-09-16-323

Expansion testing aims to decide whether an $n$-node graph has expansion at least $Phi$, or is far from any such graph. We propose a quantum expansion tester with complexity $widetilde{O}(n^{1/3}Phi^{-1})$. This accelerates the $widetilde{O}(n^{1/2}Phi^{-2})$ classical tester by Goldreich and Ron [Algorithmica '02] [12], and combines the $widetilde{O}(n^{1/3}Phi^{-2})$ and $widetilde{O}(n^{1/2}Phi^{-1})$ quantum speedups by Ambainis, Childs and Liu [RANDOM '11] and Apers and Sarlette [QIC '19] [8], respectively. The latter approach builds on a quantum fast-forwarding scheme, which we improve upon by initially growing a seed set in the graph. To grow this seed set we use a so-called evolving set process from the graph clustering literature, which allows to grow an appropriately local seed set.

Source Quantum | The open journal for quantum science Expansion Testing using Quantum Fast-Forwarding and Seed Sets

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