Classical Limit(s) of Quantum Field Theories

Benjamin H. Feintzeig, J.T. Librande, Rory Soiffer

Jürgen Berges

J. Alfaro, Luis Huerta

Jincheng Zhang

Quantum field theory (QFT) encompasses a vast and complex landscape of physical phenomena, making accurate simulation a significant challenge. Classical computers struggle to handle the exponential scaling of the computational cost with increasing system size, limiting the exploration of these theories. Hybrid quantum-classical simulation offers a promising path toward overcoming these limitations by intelligently leveraging the strengths of both paradigms. This research investigates a novel hybrid solver, the 'Quantum-Classical Hybrid Solver,' designed to efficiently simulate complex QFTs. We demonstrate the method's ability to surpass classical simulation capabilities in certain regimes while maintaining computational efficiency, offering a significant advancement in the field. The core mechanism centers around a dynamic switching between classical and quantum techniques, tailored to the specific problem at hand. This paper details the design, implementation, and preliminary results of the Hybrid Quantum-Classical Solver, highlighting its potential for accelerating QFT research.

Rob Clifton, Hans Halvorson

Entanglement has long been the subject of discussion by philosophers of quantum theory, and has recently come to play an essential role for physicists in their development of quantum information theory. In this paper we show how the formalism of algebraic quantum field theory (AQFT) provides a rigorous framework within which to analyze entanglement in the context of a fully relativistic formulation of quantum theory. What emerges from the analysis are new practical and theoretical limitations on an experimenter’s ability to perform operations on a field in one spacetime region that can disentangle its state from the state of the field in other spacelike-separated regions. These limitations show just how deeply entrenched entanglement is in relativistic quantum field theory, and yield a fresh perspective on the ways in which the theory differs conceptually from both standard nonrelativistic quantum theory and classical relativistic field theory. “...despite its conservative way of dealing with physical principles, algebraic QFT leads to a radical change of paradigm. Instead of the Newtonian view of a space-time filled with a material content one enters the reality of Leibniz created by relation (in particular inclusions) between ‘monads ’ (∼ the hyperfinite type III1 local von Neumann factors A(O) which as single algebras are nearly void of physical meaning) ” Schroer (1998, p. 302).

John T. Bruer