The Weizmann Institute of Science Faculty of Mathematics and Computer Science Walmart Lecture Series in Cryptography and Complexity Seminar Room, Room 261, Ziskind Building on Monday, January 31, 2011 at 14:30 Oded Regev Tel Aviv University will speak on Quantum One-Way Communication Can Be Exponentially Stronger than Classical Communication Abstract: 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 ${\rm poly}(n)$ 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 {\bf classical} communication complexity; no knowledge of quantum communication complexity is assumed or required.