Researchers have devised an "absurdly fast" algorithm to solve the problem of finding the fastest flow through a network.

Last November, Coudron and two colleagues took a big step toward resolving that long-standing problem: They proved that no algorithm in a broad and natural class of fast quantum algorithms can find a ...

But that speedup comes at a cost: The fast quantum algorithm finds the exit but has no idea how it got there. Researchers have long wondered whether this trade-off is inevitable.