Speaker
Description
Quantum reference frames (QRFs) are internal subsystems that transform non-trivially under a symmetry group and provide the means to describe quantum systems "from the inside" in purely relational terms. QRFs are therefore essential whenever no external reference frame for the relevant symmetry group is available. As such, they play a central role in several research areas, ranging from quantum foundations and quantum information to gauge theory and (quantum) gravity.
However, QRFs have so far been developed primarily in quantum-mechanical settings, while much less is understood about their formulation in quantum field theory (QFT). In this talk, based on ongoing work with Ivan Agullo, I will introduce a notion of localised quantum reference fields in linear QFT. These are localised finite-dimensional subsystems of a quantum field theory that allow quantum fields to be described "from the inside". Focusing on the simple example of a real massless scalar field in 1+1-dimensional Minkowski spacetime, I will illustrate how some of the key features of the QRF programme, such as the quantum relativity of subsystems, also arise in QFT.