* Note the unusual location for our group meeting. The Division Room is not available tomorrow. Hi everyone, This week Dr. Hugo Cable who is visiting from Bristol will tell us about his recent work on the boundary between classical and quantum computation. Please see the title and abstract of his talk below. See you there, Felipe Herrera ****** *Title*: SIMULATING CONCORDANT COMPUTATION *Abstract:* Quantum computation enables algorithms with exponential and polynomial speedup relative to counterparts on classical computers. However, the class of quantum algorithms which fail to admit any speed-up is not well characterized. For algorithms using only pure quantum states, speedup requires entanglement to scale with the problem size (2003). For mixed states, there is no such general result so far. Concordant computation is a model for which only classical mixed-state correlations are allowed (no entanglement and no discord) and, even in this special case, the question of whether speedup is ruled out has only partially been answered (arXiv:1006.4402 Bryan Eastin). We present new results which almost – but not entirely - settles this in the affirmative.