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Physica Scripta

A low-energy interferometric test of coherence-dependent light propagation

Chakir Fikri

Published Aug 3, 2026• 0 citations
Publisher

Abstract

Abstract The conceptual tension between quantum nonlocality and relativistic causality motivates scenarios in which Lorentz invariance is an emergent rather than fundamental symmetry. Within such scenarios, optical propagation may retain a weak dependence on properties of an underlying quantum substrate, including the coherence of nearby quantum systems. We introduce a phenomenological model in which optical propagation depends weakly on the quantum coherence of a nearby ancillary control system. To test this hypothesis, we propose a quantum-controlled Mach–Zehnder interferometric (MZI) protocol comparing coherent and incoherent ancillary states having identical populations. Standard quantum mechanics predicts identical photon-counting statistics in both configurations, whereas the proposed phenomenological model predicts additional stochastic phase fluctuations leading to an excess phase-noise variance in the coherent-control configuration. We derive the corresponding statistical sensitivity, discuss possible implementations based on state-of-the-art fiber MZIs, and estimate illustrative experimental bounds on the coherence–propagation coupling parameter.

DOI
10.1088/1402-4896/ae941a

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Abstract The conceptual tension between quantum nonlocality and relativistic causality motivates scenarios in which Lorentz invariance is an emergent rather than fundamental symmetry. Within such scenarios, optical propagation may retain a weak dependence on properties of an underlying quantum substrate, including the coherence of nearby quantum systems. We introduce a phenomenological model in which optical propagation depends weakly on the quantum coherence of a nearby ancillary control system. To test this hypothesis, we propose a quantum-controlled Mach–Zehnder interferometric (MZI) protocol comparing coherent and incoherent ancillary states having identical populations. Standard quantum mechanics predicts identical photon-counting statistics in both configurations, whereas the proposed phenomenological model predicts additional stochastic phase fluctuations leading to an excess phase-noise variance in the coherent-control configuration. We derive the corresponding statistical sensitivity, discuss possible implementations based on state-of-the-art fiber MZIs, and estimate illustrative experimental bounds on the coherence–propagation coupling parameter.
The conceptual tension between nonlocality and relativistic causality motivates scenarios in which Lorentz invariance emerges as an effective low-energy symmetry rather than a fundamental property. We present a phenomenological framework inspired by Bohmian dynamics and analogue gravity, where collective excitations of a superfluid-like medium exhibit emergent Lorentzian propagation with an effective light speed. Beyond conventional dispersion tests, we predict a novel low-energy signature: contextual sensitivity of propagation to quantum coherence in nearby control systems, inducing small fluctuations of the effective light cone. We propose a feasible Mach–Zehnder interferometric protocol to probe these effects via precision differential measurements, opening a new experimental route to explore spacetime symmetries.
Standard decoherence models predict that the degradation of optical fringe visibility is independent of the inertial mass of surrounding macroscopic bodies, provided environmental and information-theoretic couplings are held constant. We propose an experimental protocol to test for an unmodeled, mass-dependent decoherence channel. By parameterizing a hypothesized mass-coupled attenuation term, we derive a 1/r exponential visibility decay model resulting from the path integration of an inverse-square potential. We outline a modified Mach-Zehnder interferometer utilizing a decoupled 10kgTungsten mass placed near a single optical arm, including a strict symmetry-control protocol. This design explicitly isolates inertial mass from quantum measurement. We establish a required statistical integration target of N10^6 coincident counts to bound the phenomenological coupling coefficient above standard optical noise floors.
Abstract The relation between interference visibility and path distinguishability is a core pillar of quantum complementarity and decoherence theory. In standard quantum mechanics, all coherence decay in interferometric systems is attributed exclusively to path information leakage, which establishes a one-to-one relation between environmental distinguishability and fringe visibility. However, a fundamental question remains experimentally untested: whether discrete quantized energy exchange between light and matter can degrade quantum coherence independently of path distinguishability. In this work, we propose a high-precision cavity-QED experiment based on a Mach–Zehnder interferometer to decouple interaction modality from path information. A single trapped Rb atom inside an optical cavity is placed in one interferometer arm, enabling fully switchable light–matter interaction regimes: resonant discrete energy exchange and far-detuned continuous dispersive interaction. To eliminate systematic artifacts, we employ environmental state tomography to rigorously equalize the path distinguishability in both operational regimes. Furthermore, we systematically compensate all linear dynamical differences between resonant and dispersive cavity responses, including group delay, spectral distortion, and temporal mode mismatch. With all standard decoherence and dynamical contributions precisely calibrated, standard quantum mechanics predicts identical interference visibility for resonant and dispersive interactions. In contrast, a physically motivated alternative conjecture suggests that discrete energy exchange can induce intrinsic coherence suppression even at fixed path distinguishability. The two scenarios yield experimentally distinguishable visibility differences. Our scheme utilizes mature single-atom cavity quantum optics techniques without low-temperature superconducting devices, providing a robust and accessible platform to resolve this long-standing open question in quantum interferometry. The complete optical layout, timing sequence, tomography calibration, statistical criteria, and error suppression strategies are presented. This experiment offers a decisive experimental benchmark for the fundamental relationship between light–matter interaction type and quantum coherence.
We analyze in detail a system of two interferometers aimed at the detection of extremely faint phase fluctuations. The idea behind is that a correlated phase-signal like the one predicted by some phenomenological theory of Quantum Gravity (QG) could emerge by correlating the output ports of the interferometers, even when in the single interferometer it confounds with the background. We demonstrated that injecting quantum light in the free ports of the interferometers can reduce the photon noise of the system beyond the shot-noise, enhancing the resolution in the phase-correlation estimation. Our results confirm the benefit of using squeezed beams together with strong coherent beams in interferometry, even in this correlated case. On the other hand, our results concerning the possible use of photon number entanglement in twin beam state pave the way to interesting and probably unexplored areas of application of bipartite entanglement and, in particular, the possibility of reaching surprising uncertainty reduction exploiting new interferometric configurations, as in the case of the system described here.
A novel method of macroscopically entangled light-pair generation is presented for a quantum laser using randomness-based deterministic phase control of coherent light in a coupled Mach-Zehnder interferometer (MZI). Unlike the particle nature-based quantum correlation in conventional quantum mechanics, the wave nature of photons is applied for collective phase control of coherent fields, resulting in a deterministically controllable nonclassical phenomenon. For the proof of principle, the entanglement between output light fields from a coupled MZI is examined using the Hong-Ou-Mandel-type anticorrelation technique, where the anticorrelation is a direct evidence of the nonclassical features in an interferometric scheme. For the generation of random phase bases between two bipartite input coherent fields, a deterministic control of opposite frequency shifts results in phase sensitive anticorrelation, which is a macroscopic quantum feature.
A novel method of macroscopically entangled light-pair generation is presented for a quantum laser using randomness-based deterministic phase control of coherent light in a Mach-Zehnder interferometer (MZI). Unlike the particle nature-based quantum correlation in conventional quantum mechanics, the wave nature of photons is applied for collective phase control of coherent fields, resulting in a deterministically controllable nonclassical phenomenon. For the proof of principle, the entanglement between output light fields from an MZI is examined using the Hong-Ou-Mandel-type anticorrelation technique, where the anticorrelation is a direct evidence of the nonclassical features in an interferometric scheme. For the generation of random phase bases between two bipartite input coherent fields, a deterministic control of opposite frequency shifts results in phase sensitive anticorrelation, which is a macroscopic quantum feature.