Quantum memory effects as a signature of the quantumness of gravity

ABSTRACT

The question of how gravity and quantum theory play together has been an elusive problem for over a century. Recently, novel approaches using concepts from quantum optics and quantum information theory have emerged to address this issue. Building on this idea, we propose a way to demonstrate quantum features of gravity through correlation measurements in a gravitationally coupled open quantum system. The non-unitary time evolution of such an open system can be viewed as arising from tracing out inaccessible environmental degrees of freedom of a larger system.

The local dynamics are particularly intriguing when the environment exhibits memory effects. These non-Markovian quantum dynamics can originate from both classical and quantum memory effects in the environment. However, recent findings show that dynamics driven by genuine quantum memory effects exhibit unique signatures impossible with a purely classical memory. Thus, measurements of local properties of an open system can probe and reveal the quantum nature of an otherwise inaccessible environment. Using this idea we construct a one-sided witness for the quantumness of gravity based on measurements of solely a single probe system.

BIOGRAPHY

Konstantin Beyer studied physics at the Technical University of Dresden, Germany. He received his PhD in 2023 under the supervision of Walter Strunz with a thesis on the measurement of work in quantum thermodynamics. Since September 2023 he is a postdoc in the group of Igor Pikovski at the Stevens Institute of Technology in Hoboken. His research is concerned with quantum information theory, open quantum system dynamics, and the interplay of quantum theory and gravity, focusing on the question of how genuine quantum signatures can be witnessed and distinguished from classical descriptions.