Physics - String Theory

Abstract: Energy plays a ubiquitous role in physics, and many physical classical field theories obey pointwise energy conditions. However, for QFTs, the pointwise stress tensor is unbounded from below. In this talk, I will derive new families of quantum null energy inequalities (QNEIs), i.e. bounds on integrated null energy, in QFTs in both two and higher dimensions. These are state-independent lower bounds on localised integrals of the stress tensor, and the first of this kind for interacting theories in higher dimensions. We will present the proofs, which include ingredients from field theory and quantum information. These results are new, fundamental constraints on null energy in all quantum field theories.