Quantum gravitational decoherence of light and matter

Abstract

Real world quantum systems are open to perpetual influence from the wider environment. Quantum gravitational fluctuations provide a most fundamental source of the environmental influence through their universal interactions with all forms of energy and matter causing decoherence. This may have subtle implications on precision laboratory experiments and astronomical observations and could limit the ultimate capacities for quantum technologies prone to decoherence. To establish the essential physical mechanism of decoherence under weak spacetime fluctuations, we carry out a sequence of analytical steps utilizing the Dirac constraint quantization and gauge invariant influence functional techniques resulting in a general master equation of a compact form that describes an open quantum gravitational system with arbitrary bosonic fields. An initial application of the theory is illustrated by the implied quantum gravitational dissipation of light as well as (non)relativistic massive or massless scalar particles. Related effects could eventually lead to important physical consequences including those on a cosmological scale and for a large number of correlated particles.

Tabletop experiments for quantum gravity: a user’s manual

“…There are strong arguments that it will be impossible to ever directly detect a single graviton, even in principle-it would generally require a detector so large and massive that a black hole would form [62][63][64]. However, there is an alternative: perhaps one could infer the existence of the graviton, or more precisely the ability of systems to spontaneously emit gravitons, by observing decoherence consistent with information lost into graviton states [65][66][67]. Unfortunately, as we review in this section, the rates of graviton-induced decoherence are extraordinarily low compared to more pedestrian channels like electromagnetic radiative damping, at least for small masses.…”

“…However, it should be noted that for very large masses the gravitational rate can actually start to dominate [68]. Beyond this order-of-magnitude estimate, we refer the reader to detailed calculations of spontaneous emission in a neutron quantum bouncer [69], simple harmonic oscillator [67], and especially the wonderful review of the 3d → 1s transition in hydrogen presented in [63,64]. Another possibility would be to look for thermalization due to an ambient graviton background.…”

Quantum principle of sensing gravitational waves: From the zero-point fluctuations to the cosmological stochastic background of spacetime

“…Recently, there has been considerable interest in experimenting with gravity using quantum instrument [1,2], to better explore its theory, predictions, and applications in uncontested regimes [3][4][5]. This trend has been established through laboratory measurements of the gravitational acceleration by ultracold atom interferometers with accuracies exceeding that achievable by conventional gravimeters [6].…”

Immirzi parameter without Immirzi ambiguity: Conformal loop quantization of scalar-tensor gravity

“…However, some felt such a practice unnatural as exemplified by Rovelli's opinion that "the result is not entirely satisfactory," remarking "the sense that there is something important which is not yet understood is unavoidable" [2], while some others have developed models with the Immirzi parameter turned into a scalar field [22][23][24]. Given gradually impending contact of LQG with the real world [1,2] and increased understanding of quantum gravity effects such as decoherence through the emission and absorption of gravitons [25][26][27][28][29][30], the physical ramifications of the Immirzi parameter on spacetime fluctuations towards the deep Planckian domain have been receiving ever more interest and attention [31].…”