This study explores quantum effects in weak gravitational fields with the aim of identifying feasible pathways towards tabletop tests of quantum gravity. Using numerical simulations of matter-wave interference for nanoparticles with masses between and kg, we investigate how environmental and fundamental decoherence mechanisms shape observable signatures. The results reveal a mass-dependent reduction in interference visibility, dropping from near unity at kg to below 0.2 at kg. Coherence times were found to exceed one second for particles lighter than 10^(-16) kg under cryogenic ultra-high-vacuum conditions, but decreased to sub-millisecond scales for kg particles at room temperature, confirming thermal radiation as the dominant source of decoherence. In parallel, collapse models such as CSL predict additional suppression of visibility for interrogation times of 0.1 s, particularly for masses above kg, enabling discrimination between environmental and intrinsic decoherence mechanisms. These findings underscore the necessity of maintaining ultra-high vacuum and cryogenic environments to detect gravitationally induced quantum phases, thereby providing a practical framework for near-future interferometry experiments. While the present work is limited to phenomenological models and simulated data, it establishes a roadmap for extending investigations to heavier mass regimes, incorporating realistic noise sources, and testing alternative collapse scenarios.
This study explores quantum effects in weak gravitational fields with the aim of identifying feasible pathways towards tabletop tests of quantum gravity. Using numerical simulations of matter-wave interference for nanoparticles with masses between and kg, we investigate how environmental and fundamental decoherence mechanisms shape observable signatures. The results reveal a mass-dependent reduction in interference visibility, dropping from near unity at kg to below 0.2 at kg. Coherence times were found to exceed one second for particles lighter than 10^(-16) kg under cryogenic ultra-high-vacuum conditions, but decreased to sub-millisecond scales for kg particles at room temperature, confirming thermal radiation as the dominant source of decoherence. In parallel, collapse models such as CSL predict additional suppression of visibility for interrogation times of 0.1 s, particularly for masses above kg, enabling discrimination between environmental and intrinsic decoherence mechanisms. These findings underscore the necessity of maintaining ultra-high vacuum and cryogenic environments to detect gravitationally induced quantum phases, thereby providing a practical framework for near-future interferometry experiments. While the present work is limited to phenomenological models and simulated data, it establishes a roadmap for extending investigations to heavier mass regimes, incorporating realistic noise sources, and testing alternative collapse scenarios.
Testing whether gravity is quantum or classical remains a cornerstone challenge in fundamental physics. We introduce a practical tabletop experiment to probe gravity's quantum nature via the gravitational Aharonov-Bohm (AB) effect in atom interferometry. Our approach hinges on two pivotal insights: First, unlike electromagnetic AB effects where constant charge ensures gauge-invariant phases for closed paths, semiclassical gravity couples to the particle's total energy, rendering the AB phase gauge-dependent and unobservable when energies differ between paths due to environmental noise or controlled perturbations. Second, in quantum gravity—treating source, particle, and field as quantum—the total phase splits into a gauge-dependent particle contribution and a gauge-invariant source backreaction, yielding precisely half the nominal AB phase as observable. This halved phase discriminates quantum from classical gravity without requiring massive superpositions, aligning with existing technology. Remarkably, Overstreet et al.'s (Science 375, 226 (2022)) data already reveal a nonzero measured AB phase, providing the first experimental evidence for gravitational quantization.
FINDING: Tabletop quantum-gravity tests probe Planck-scale discreteness via matter-wave interferometry and optomechanical superposition, not yet yielding a confirmed equation but constraining collapse models and graviton signatures. | MATH: Planck length lP=ℏG/c3≈1.616×10−35m; Planck mass mP=ℏc/G≈2.176×10−8kg; decoherence rate for gravitationally-induced collapse (Penrose–Diosi): Γ∼ΔEG/ℏ, where ΔEG=2G∫∫∣r−r′∣[ρ1(r)−ρ2(r)][ρ1(r′)−ρ2(r′)]d3rd3r′; Folman T³ experiment: cubic scaling of phase shift Δϕ∝T3 (where T is free-fall time), testing equivalence principle at quantum level. | CONNECTION: The ratio lP2/λC2 (Planck length squared over Compton wavelength squared) appears in gravitationally-induced entanglement rates — nume Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com
FINDING: Quantum gravity tests are converging on tabletop interferometry experiments probing Planck-scale effects via entanglement and superposition of massive systems. | MATH: Key scales: Planck mass mP=ℏc/G≈2.176×10−8 kg; Planck length lP=ℏG/c3≈1.616×10−35 m. The proposed experiments (e.g., Ron Folman's T³, matter-wave interferometry) require measuring phase shifts Δϕ∼(m1m2Gt3)/(ℏd3) — a cubic time dependence, hence "T-cubed." Decoherence rate for gravitational entanglement: Γ∼(Gm1m2/ℏd)2⋅τ — dimensionless coupling αG=Gm1m2/(ℏcd)≪1 at tabletop scales, yet measurable via entanglement witness. | CONNECTION: The ratio mP2/(m1m2) for typical masses (e.g., 10−14 kg) yields ∼1012 — not directly harmonic. However, the T³ phase term contains t3 — a cubic symmetry (tetrahedral Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com
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.
The gravitational decoherence field studies the suppression of coherence in quantum systems caused by effects rooted in the gravitational interaction. This models are not just important to yield interesting ideas about the search, in regimes others than the Planck scale, for the interplay between quantum mechanics and general relativity, but also from a theoretical point of view. The fact that the gravitational field can not be shielded opens the question of how strong will the gravitational ‘environment’ decohere a quantum system? and if this decoherence can somehow explain the absence of macroscopical super- positions? This thesis studies in depth the ‘Classical Channel Gravity’ (CCG) model, a recent proposal of gravitational decoherence that assumes that the gravitational interac- tion is always accompanied with an intrinsic decoherence mechanism which ensures that there is no transmission of quantum information between the parties involved. This model can be understood a series of weak continuous quantum measurements accompanied with a feedback term produced by some underlying hidden gravitational degrees of freedom. We first study all the possible emergent dynamics from collisional Markovian dynamics; these ones range from exact unitary to arbitrary fast decoherence (Zeno effect). The second part of the thesis is devoted to study the Newtonian and post Newtonian limits of the CCG model, with particular focus on the testability features of CCG. In particular, we apply this model to coupled clocks and find that the amount of decoherence predicted by CCG is the same as the decoherence that an ‘environment of clocks’ will imprint in a single clock in the context of unitary evolution. On the other hand, we find that this effect is far from being detectable with the current achieved time accuracy. However, CCG as a model for multi partite systems and two systems with very different masses seems to yield an amount of decoherence that is not only able to be detectable with current experiments but also seems to indicate that this model is ruled out. Nevertheless, we also mention potential caveats with our assumptions and discuss other physically motivated directions to further study this result. Finally, we also explore the extension of CCG for the cosmological scenario. In this context the scale factor is being decohered by test particles ‘sitting’ on spacetime. We find that this decoherence will be seen by an observer unaware of the CCG fundamental mechanism as an emergent form of dark energy filling the universe.
This work presents numerical and theoretical evidence for a testable regime in which semiclassical Schrödinger–Newton dynamics predict a state-dependent gravitational self-interaction in mesoscopic quantum systems. Using large-scale Split-Step Fourier Method (SSFM) simulations, we identify a mass window (≈10⁻¹¹–10⁻¹⁰ kg) where quantum coherence and gravitational self-interaction coexist without immediate decoherence. In this regime, the gravitational self-energy depends smoothly on the spatial structure of the quantum state, leading to a differential phase evolution between superposition states with identical external potentials but different mass-density distributions. The predicted phase signal scales as m² and reaches experimentally relevant magnitudes (Δφ ≈ 10⁻³ rad) for millisecond evolution times, making the effect accessible to next-generation matter-wave and optomechanical interferometry. The work systematically validates the numerical approach, demonstrates energy conservation and convergence of the nonlinear dynamics, identifies a stable “breathing-mode” regime near 10⁻¹⁰ kg, and isolates the gravitational origin of the effect via null tests with the Schrödinger–Newton term removed. This preprint makes no claim regarding spacetime engineering, geometry manipulation, or violations of the equivalence principle. It is explicitly framed as a falsifiable test of semiclassical gravity in a previously inaccessible experimental regime. Confirmation or null detection would provide strong constraints on Schrödinger–Newton–type models and inform the ongoing search for the correct quantum–gravity interface.