Quantum gravity signatures in gravitational wave detectors placed inside a harmonic trap potential

TL;DR

This paper investigates quantum gravity signatures in gravitational wave detectors placed inside a harmonic trap, revealing a spontaneous graviton emission that indicates quantum effects absent in semi-classical models.

Contribution

It introduces a quantum mechanical model of a gravitational wave detector in a harmonic trap, highlighting quantum signatures like spontaneous graviton emission.

Findings

Transition probability matches semi-classical absorption for resonant cases

Spontaneous emission of a single graviton observed, absent in semi-classical models

Provides a potential direct signature of linearized quantum gravity

Abstract

In this work, we consider a general gravitational wave detector of gravitational wave interacting with an incoming gravitational wave carrying plus polarization only placed inside a harmonic trap. This model can be well acquainted with the description of a resonant detector of gravitational wave as well. The well known detector-gravitational wave interaction scenario uses the method of a semi classical approach where the detector is treated quantum mechanically but the gravitational wave is considered at a classical level. In our analysis, we use a discrete mode decomposition of the gravitational wave perturbation which results in a Hamiltonian involving the position and momentum operators corresponding to the gravitational wave and the harmonic oscillator. We have then calculated the transition probability for the harmonic oscillator-gravitational wave tensor product state for going from an initial state to some unknown final state. Using the energy flux relation of the gravitational waves, we observe that if we consider the total energy as a combination of the number of gravitons in the initial state of the detector then the transition probability for the resonant absorption case scenario takes the analytical form which is exactly similar to the semi-classical absorption case. In case of the emission scenario, we observe a spontaneous emission of a single graviton which was completely absent in the semi-classical analouge of this model. This therefore gives a direct signature of linearized quantum gravity.