Spring 2021

Timothy Berkelbach (Columbia & Flatiron Institute)

Timothy Berkelbach
Thursday, February 18, 2021 - 4:00pm

Ab initio wavefunction-based quantum chemistry represents a tantalizing alternative to density functional theory for problems in materials science, due to the former's ability to achieve high accuracy with systematic improvability. I will give an overview of our group's research efforts in this direction, describing theoretical and methodological developments at the periodic Hartree-Fock and post-Hartree-Fock levels (especially perturbation theory and coupled-cluster theory) and connections to popular Green's function-based techniques such as the random-phase...

Vikesh Siddhu (Carnegie Mellon University)

Vikesh Siddhu
Thursday, February 11, 2021 - 4:00pm

Entanglement lies at the root of quantum theory. It is a remarkable resource that is generally believed to diminish when entangled systems interact with their environment. On the contrary, we find that engaging a system with its environment increases its ability to retain entanglement. The maximum rate of retaining entanglement is given by the quantum channel capacity. We counter-intuitively boost the quantum capacity of a channel by allowing it to leak almost all quantum information to...