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Bare Quantum Null Energy Condition.

Zicao Fu1, Donald Marolf1

  • 1Department of Physics, University of California, Santa Barbara, California 93106, USA.

Physical Review Letters
|March 16, 2018
PubMed
Summary

Researchers explored the quantum null energy condition (QNEC), a relationship between quantum field theory energy and entropy. They found that a generalized QNEC can hold even when divergences do not cancel, applying to unrenormalized quantities in quantum gravity.

Area of Science:

  • Quantum Field Theory
  • Quantum Gravity
  • Theoretical Physics

Background:

  • The quantum null energy condition (QNEC) relates quantum field theory energy to derivatives of von Neumann entropy.
  • Previous studies focused on cases with divergences canceling, yielding finite QNEC.
  • The quantum focusing conjecture is a special case of QNEC for on-shell metrics.

Purpose of the Study:

  • To investigate the validity of QNEC in more general cases where divergences do not cancel.
  • To explore the applicability of QNEC to bare (unrenormalized) quantities.
  • To extend the understanding of QNEC beyond locally stationary null congruences.

Main Methods:

  • Analysis of divergences in quantum field theory energy and von Neumann entropy.
  • Formal perturbation theory at small Planck length.

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  • Examination of semiclassical theories of quantum gravity.

    • Main Results:

    • A generalized quantum null energy condition (QNEC) can hold for bare quantities even when divergences do not cancel.
    • The study considers cases beyond locally stationary null congruences.
    • The quantum focusing conjecture is identified as a specific instance of the bare QNEC.

    Conclusions:

    • The quantum null energy condition is more broadly applicable than previously thought, extending to unrenormalized quantities.
    • This work provides a more general framework for studying QNEC in quantum gravity.
    • The findings offer new insights into the interplay between quantum energy and entropy in curved spacetimes.