Table-top proposals to test gravity-mediated entanglement aim to distinguish coherent gravitational interactions from classical dephasing processes that generate identical phases on both interferometers. A particularly important contribution is platform-invariant timing noise, which can be accessed through optical-clock cross-spectra and frequency-transfer links. In this work we (i) derive the mapping from clock cross-spectra to an effective common-mode dephasing rate, (ii) show that the corresponding dynamical channel is LOCC and therefore unable to generate entanglement, and (iii) combine published clock and interferometer noise floors to obtain quantitative bounds on the ratio between common-mode and local dephasing rates in representative gravity-entanglement proposals. Across QGEM-, MAQRO-, and levitated-nanoparticle regimes we find a robust hierarchy $γ_{\rm com}/γ_{\rm loc}\sim10^{-9}$--$10^{-11}$, identifying platform-invariant timing noise as a negligible but calibratable background. We further derive visibility and Bell--CHSH thresholds in the presence of both common-mode and local dephasing, and illustrate the full calibration workflow with a simple synthetic example anchored to state-of-the-art clock metrology. Extended derivations and statistical tools are provided in the Supplemental Material.
Table-top proposals to test gravity-mediated entanglement aim to distinguish coherent gravitational interactions from classical dephasing processes that generate identical phases on both interferometers. A particularly important contribution is platform-invariant timing noise, which can be accessed through optical-clock cross-spectra and frequency-transfer links. In this work we (i) derive the mapping from clock cross-spectra to an effective common-mode dephasing rate, (ii) show that the corresponding dynamical channel is LOCC and therefore unable to generate entanglement, and (iii) combine published clock and interferometer noise floors to obtain quantitative bounds on the ratio between common-mode and local dephasing rates in representative gravity-entanglement proposals. Across QGEM-, MAQRO-, and levitated-nanoparticle regimes we find a robust hierarchy γcom/γloc∼10−9--10−11, identifying platform-invariant timing noise as a negligible but calibratable background. We further derive visibility and Bell--CHSH thresholds in the presence of both common-mode and local dephasing, and illustrate the full calibration workflow with a simple synthetic example anchored to state-of-the-art clock metrology. Extended derivations and statistical tools are provided in the Supplemental Material.
This work presents a model-independent analysis of gravity-mediated entanglement based on the geometric structure of interaction-induced phase evolution. Using a minimal two-body phase model inspired by recent gravity-mediated entanglement proposals, it is shown that quantum entanglement between initially separable systems arises if and only if the induced phase structure is non-factorable. The central result identifies a gauge-invariant plaquette phase as a necessary and sufficient operational condition for entanglement generation. When this plaquette invariant is nonzero, standard quantum information diagnostics—such as negativity, concurrence, and Bell–CHSH correlations—confirm the presence of entanglement. When the invariant is eliminated, entanglement vanishes identically, even when individual phase magnitudes remain nonzero. A comprehensive suite of falsification tests is applied, including local phase factorization, plaquette removal, deterministic and stochastic phase scrambling, permutation symmetry tests, LOCC protocols, causal reordering, and controlled noise injection. Across all tests, entanglement survives exclusively in the presence of non-factorable phase structure. Scaling analyses further demonstrate consistent dependencies on mass, interaction time, separation distance, and superposition size, yielding a distinctive interaction fingerprint incompatible with classical or semiclassical channels. The framework is fully operational and does not assume a specific theory of quantum gravity. Instead, it provides a concrete, experimentally accessible criterion for probing nonclassical aspects of gravity using near-term interferometric platforms. The results sharpen the interpretational foundations of gravity-mediated entanglement proposals by isolating the minimal structural feature responsible for entanglement generation.
This manuscript develops three concrete, falsifiable predictions based on a framework in which time and space are operationally equivalent, and classical reality is understood as the record. In this scalar-clock / awareness-tensor / Trinity picture, an observation is any physical process that stabilizes correlations into durable, revisitable records, and gravity is interpreted as time decoherence: clock-locking and time selection into dominant mass time-zones. The paper introduces three phenomenological parameters that are exactly zero in standard GR+QM: (i) ϵ\epsilonϵ, the sensitivity of co-located clock rates to engineered decoherence and monitoring strength; (ii) η\etaη, the sensitivity of effective gravitational acceleration to record-export structure at fixed mass distribution; and (iii) a scalar time-mismatch scale ΔT∗\Delta T_\astΔT∗, beyond which interference visibility near a mass exhibits a protocol-dependent threshold. These parameters are tied to operational proxies: clock-locking depth, time mismatch, and coupling gradients. From this framework, three testable predictions follow: Entanglement-dependent time dilation: Two identical, co-located precision clocks in the same gravitational potential but in different record-coupling regimes (high vs. low monitoring and decoherence) should exhibit a small, persistent differential drift that tracks clock-locking depth, not altitude or velocity. Gravity modulation by engineered decoherence: In a torsion balance, atom interferometer, or precision gravimeter, the measured acceleration toward a test mass should differ slightly between “decoherence OFF” and “decoherence ON” conditions, even when the mass distribution and EM fields are unchanged. The key signature is a protocol-locked Δg\Delta gΔg that appears only when scattered quanta are recorded, not when the same fields are present but their outputs are dumped locally. Entanglement horizon near mass: In a matter-wave interferometer, as one arm approaches a mass (or as the mass is increased), interference visibility should drop at a characteristic threshold set by scalar-clock mismatch and record structure. This defines an “entanglement horizon” in time-mismatch space, distinct from smooth environmental decoherence. For each effect, the paper defines explicit null hypotheses, identifies leading systematics, and sketches minimal experimental protocols compatible with current or near-term optical clocks, gravimetry, and matter-wave interferometry platforms. A brief CPT-compatibility analysis clarifies that microscopic dynamics remain CPT-symmetric in the usual QFT sense; any asymmetries arise only at the coarse-grained level of record formation and clock-locking. The proposals can therefore be read either as parameterized extensions of GR+QM using measurement architecture as an additional knob, or as an operational test of a broader “gravity as time decoherence” interpretation in which geometry becomes explicitly record-sensitive. This Version 2 is a revised and expanded update of the original upload, adding a phenomenology-first summary, clarifying the roles of the parameters (ϵ,η,ΔT∗)(\epsilon,\eta,\Delta T_\ast)(ϵ,η,ΔT∗), and situating the framework more explicitly relative to existing work on gravity-related decoherence, hybrid classical–quantum gravity, and clock/interferometry proposals (Diósi–Penrose, Bassi, Anastopoulos–Hu, Oppenheim, Zych–Costa–Pikovski–Brukner, Bose et al.). The updated version explicitly restricts the criterion to record-sensitive effects, rather than any effect. It explicitly spells out what “record formation on/off” means in practice: detectors and logging are turned on/off while the physical fields are held fixed, i.e., outputs are either stored or not stored. This version tightens falsifiability and lab usability. It (i) commits to explicit benchmark model families for the three predictions, each reducing to standard physics when ϵ=η=κ=0\epsilon=\eta=\kappa=0ϵ=η=κ=0; (ii) defines an unambiguous export-axis variable via the exported mutual-information rate I˙XR\dot I_{XR}I˙XR and export depth E\mathcal{E}E, enabling cross-platform comparisons; (iii) adds a fully worked, platform-specific optical lattice clock pilot (C1 vs C2 export-only toggle) including invariance audits, confound/error budgeting, preregistered power/discriminability analysis, and an end-to-end analysis pipeline; and (iv) upgrades mandatory reporting/preregistration templates so null results produce publishable bounds on (ϵ,η,κ)(\epsilon,\eta,\kappa)(ϵ,η,κ).
Given a unitary evolution U on a multipartite quantum system and an ensemble of initial states, how well can U be simulated by local operations and classical communication (LOCC) on that ensemble? We answer this question by establishing a general, efficiently computable upper bound on the maximal LOCC simulation fidelity—what we call an “LOCC inequality.” We then apply our findings to the fundamental setting where U implements a quantum Newtonian Hamiltonian over a gravitationally interacting system. Violation of our LOCC inequality can rule out the LOCCness of the underlying evolution, thereby establishing the nonclassicality of the gravitational dynamics, which can no longer be explained by a local classical field. As a prominent application of this scheme we study systems of quantum harmonic oscillators initialized in coherent states following a normal distribution and interacting via Newtonian gravity, and discuss a possible physical implementation with torsion pendula. One of our main technical contributions is the analytical calculation of the above LOCC inequality for this family of systems. As opposed to existing tests based on the detection of gravitationally mediated entanglement, our proposal works with coherent states alone, and thus it does not require the generation of largely delocalized states of motion nor the detection of entanglement, which is never created at any point in the process. Published by the American Physical Society 2024
The notion of time is given a different footing in quantum mechanics and general relativity, treated as a parameter in the former and being an observer-dependent property in the latter. From an operational point of view time is simply the correlation between a system and a clock, where an idealized clock can be modeled as a two-level system. We investigate the dynamics of clocks interacting gravitationally by treating the gravitational interaction as a classical information channel. This model, known as the classical-channel gravity (CCG), postulates that gravity is mediated by a fundamentally classical force carrier and is therefore unable to entangle particles gravitationally. In particular, we focus on the decoherence rates and temporal resolution of arrays of N clocks, showing how the minimum dephasing rate scales with N, and the spatial configuration. Furthermore, we consider the gravitational redshift between a clock and a massive particle and show that a classical-channel model of gravity predicts a finite-dephasing rate from the nonlocal interaction. In our model we obtain a fundamental limitation in time accuracy that is intrinsic to each clock.
Tests of gravity-mediated entanglement aim to determine whether two massive objects in spatial superposition can become entangled through their mutual gravitational interaction. In an ideal model, the two objects are often treated as pointlike branches, but real wave packets have a finite width and are also exposed to dephasing and residual non-gravitational forces. We study these effects in a two-branch gravitational cat-state model with Gaussian wave packets. The Newtonian interaction is averaged over the finite wave-packet width, and spatially correlated dephasing is included phenomenologically. We then ask a practical question: when does the generated state remain useful rather than merely entangled? To answer this, we examine Bell violation, teleportation fidelity, coherent information, Fisher information, and state distinguishability. We find finite parameter windows where the same state is Bell-nonlocal and teleportation-useful, but these windows shrink as the wave packets become broader or the dephasing becomes stronger. We also show that a residual electrostatic branch interaction can coherently cancel the gravitational nonlocal phase and strongly suppress the operational signal. The results identify finite-width and electrostatic tolerance boundaries that should be considered in future tests of gravity-mediated entanglement.
We show that gravitational curvature can control the generation of nonlocal quantum correlations in a hybrid qubit-mechanical device. The tidal field of a nearby source mass modifies the susceptibility of a shared mechanical oscillator, thereby tuning an oscillator-mediated qubit-qubit interaction and the resulting entangling phase. An exact treatment of the dynamics reveals stroboscopic geometric gates whose accumulated phase is directly sensitive to gravitational curvature. Treating the curvature as an unknown parameter, we derive the ultimate quantum limit for its estimation and identify a parity-based measurement that saturates this bound. Solving the full master equation with the mechanical mode retained explicitly, we find that thermal occupation of the mediator suppresses entanglement between the closure times but is undone at each closure, exactly in the unitary limit for any initial mechanical temperature, so that ground-state cooling of the oscillator is not a prerequisite for the protocol. Mechanical damping and qubit dephasing behave differently: they leak branch information irreversibly to the environment, and it is the heating and dephasing rates, rather than the bath occupation alone, that limit the entanglement visibility and the number of usable interrogation loops. In contrast to gravity-mediated entanglement proposals, entanglement is generated by the mechanical oscillator while gravity acts solely as a classical control field. We quantify the achievable curvature parameters; all curvature dependencies are analytic, allowing for exact rescaling of the results. The scheme therefore demonstrates gravitational control of a quantum interaction and provides a route to curvature sensing based on a nonlocal two-qubit phase rather than on local phase measurements.