Quantum one-way communication can be exponentially stronger than classical communication
Seminar Room 1, Newton Institute
In STOC 1999, Raz presented a (partial) function for which there is a quantum protocol communicating only O(log n) qubits, but for which any classical (randomized, bounded-error) protocol requires poly(n) bits of communication. That quantum protocol requires two rounds of communication. Ever since Raz's paper it was open whether the same exponential separation can be achieved with a quantum protocol that uses only one round of communication. In other words, can quantum one-way communication be exponentially stronger than classical two-way communication? Here we settle this question in the affirmative.
Based on joint work with Bo'az Klartag.
NOTE: This talk is about lower bounds for *classical* communication complexity; no knowledge of quantum communication complexity is assumed or required.