Schemes of gravitationally induced decoherence are being actively investigated as possible mechanisms for the quantum-to-classical transition. Here, we introduce a decoherence process due to quantum gravity effects. We assume a foamy quantum spacetime with a fluctuating minimal length coinciding on average with the Planck scale. Considering deformed canonical commutation relations with a fluctuating deformation parameter, we derive a Lindblad master equation that yields localization in energy space and decoherence times consistent with the currently available observational evidence. Compared to other schemes of gravitational decoherence, we find that the decoherence rate predicted by our model is extremal, being minimal in the deep quantum regime below the Planck scale and maximal in the mesoscopic regime beyond it. We discuss possible experimental tests of our model based on cavity optomechanics setups with ultracold massive molecular oscillators and we provide preliminary estimates on the values of the physical parameters needed for actual laboratory implementations.
Schemes of gravitationally induced decoherence are being actively investigated as possible mechanisms for the quantum-to-classical transition. Here, we introduce a decoherence process due to quantum gravity effects. We assume a foamy quantum spacetime with a fluctuating minimal length coinciding on average with the Planck scale. Considering deformed canonical commutation relations with a fluctuating deformation parameter, we derive a Lindblad master equation that yields localization in energy space and decoherence times consistent with the currently available observational evidence. Compared to other schemes of gravitational decoherence, we find that the decoherence rate predicted by our model is extremal, being minimal in the deep quantum regime below the Planck scale and maximal in the mesoscopic regime beyond it. We discuss possible experimental tests of our model based on cavity optomechanics setups with ultracold massive molecular oscillators and we provide preliminary estimates on the values of the physical parameters needed for actual laboratory implementations.
Abstract Schemes of gravitationally induced decoherence are being actively investigated as possible mechanisms for the quantum-to-classical transition. Here, we introduce a decoherence process due to quantum gravity effects. We assume a foamy quantum spacetime with a fluctuating minimal length coinciding on average with the Planck scale. Considering deformed canonical commutation relations with a fluctuating deformation parameter, we derive a Lindblad master equation that yields localization in energy space and decoherence times consistent with the currently available observational evidence. Compared to other schemes of gravitational decoherence, we find that the decoherence rate predicted by our model is extremal, being minimal in the deep quantum regime below the Planck scale and maximal in the mesoscopic regime beyond it. We discuss possible experimental tests of our model based on cavity optomechanics setups with ultracold massive molecular oscillators and we provide preliminary estimates on the values of the physical parameters needed for actual laboratory implementations.
We introduce and investigate a decoherence mechanism due to quantum gravity effects. By assuming the existence of a fluctuating minimal space length scale, we derive a master equation in Lindblad form induced by the minimal-length-deformed uncertainty principle and we analyze its implications for the decoherence time and the state entropy variation. Further, we show how our model predicts a localization in energy and decoherence timescales consistent with the currently available observational evidence. Finally, we discuss schemes for the experimental verification of our model based on cavity optomechanics setups with ultracold massive molecular oscillators.
Laboratory-based experimental tests remain a central challenge in the study of the quantum-gravity interface. We present a quantitative, experimentally testable prediction for gravitationally induced quantum decoherence of spatial superpositions in levitated optomechanical systems. Starting from two independently well-tested physical elements—the quantum nature of material energy-momentum fluctuations (established in particle physics) and the linear response kernel of classical geometry (derived from the weak-field limit of general relativity and verified by gravitational-wave observations)—and supplementing them with a minimal extension postulate for superposition states, we obtain a rigid scaling law for the gravitational decoherence rate: \Gamma \sim G M^2 d^2 / (\hbar L^3) \cdot \Phi(l_*/L), where M is the mass of the object, d the spatial separation of the superposition branches, L the characteristic linear dimension, and \Phi a dimensionless function encoding the unknown ultraviolet cutoff scale l_* of the effective geometric noise. The structural form \Gamma \propto M^2 d^2 / L^3 contains no free adjustable parameters; the overall amplitude is set by the choice of l_*. Identifying l_* with the Planck length \ell_P = \sqrt{\hbar G / c^3}—the only known scale bridging quantum theory and gravity—yields \Phi \sim \mathcal{O}(1) and a specific numerical target. For current levitated nanoparticle experiments (M \sim 10^{-14}\,\text{kg}, d \sim 10^{-7}\,\text{m}, L \sim 10^{-6}\,\text{m}), this Planck-scale hypothesis predicts a decoherence rate of order 1\,\text{Hz}, placing it within the foreseeable sensitivity window of next-generation optomechanical setups. We discuss the exclusive physical signatures distinguishing this mechanism from environmental decoherence channels and outline explicit falsification conditions, providing experimental groups with a concrete target to probe the quantum-gravity interface in the laboratory.
We consider the scenario of a fluctuating spacetime due to a deformed commutation relation with a fluctuating deformation parameter or to a fluctuating metric tensor. By computing the resulting dynamics and averaging over these fluctuations, we find that a system experiences a decoherence in the momentum basis. We studied the predictions of the model for a free particle and an harmonic oscillator. Using experimental data taken from a mechanical oscillator prepared in quantum states of motion, we put a bound on the free parameters of the considered model. In addition, we comment on how these measurements can also provide bounds to other phenomenological quantum gravity models, such as the length scale for nonlocal dynamics.
Several phenomenological approaches to quantum gravity predict the existence of a minimal measurable length and/or a maximum measurable momentum near the Planck scale. When embedded into the framework of quantum mechanics, such constraints induce a modification of the canonical commutation relations and thus a generalization of the Heisenberg uncertainty relations, commonly referred to as generalized uncertainty principle (GUP). Different models of quantum gravity imply different forms of the GUP. For instance, in the framework of string theory the GUP is quadratic in the momentum operator, while in the context of doubly special relativity it includes an additional linear dependence. Among the possible physical consequences, it was recently shown that the quadratic GUP induces a universal decoherence mechanism, provided one assumes a foamy structure of quantum spacetime close to the Planck length. Along this line, in the present work we investigate the gravitational decoherence associated to the linear-quadratic GUP and we compare it with the one associated to the quadratic GUP. We find that, despite their similarities, the two generalizations of the Heisenberg uncertainty principle yield decoherence times that are completely uncorrelated and significantly distinct. Motivated by this result, we introduce a theoretical and experimental scheme based on cavity optomechanics to measure the different time evolution of nonlocal quantum correlations corresponding to the two aforementioned decoherence mechanisms. We find that the deviation between the two predictions occurs on time scales that are macroscopic and thus potentially amenable to experimental verification. This scenario provides a possible setting to discriminate between different forms of the GUP and therefore different models of quantum gravity.
Several theories of quantum gravity propose the existence of a minimal measurable length and maximum measurable momentum near the Planck scale. When integrated into the framework of quantum mechanics, such restrictions lead to the generalization of the Heisenberg uncertainty principle, which is commonly referred to as the generalized uncertainty principle (GUP). The GUP has been applied to a plethora of physical models in order to provide further insights on our understanding of the Universe, both in the macroscopic and the microscopic regime. Nevertheless, the corrections related to GUP are expected to be extremely small, which thus renders experimental verification a difficult task. Therefore, phenomenological approaches on a qualitative level are typically addressed with the aim of enhancing our possibility of detecting these tiny effects. Motivated by a recent work on a universal decoherence mechanism stemming from the standard formulation of GUP, we extend the ideas contained therein by considering a more general form of GUP which includes linear and quadratic momentum terms to examine its implications. To achieve such a picture, we equip the deformation parameter appearing in front of all momentum terms with a stochastic nature, so that the effective decoherence mechanism emerges by taking the average over fluctuations. We find that, despite the apparently small differences among the two generalizations of the Heisenberg uncertainty principle, the consequences at the level of the universal decoherence mechanism they entail is significant, as they predict decoherence times that are completely uncorrelated and distinct.