arXiv subjects

Linda M. van Manen

Publications and source records attributed to Linda M. van Manen.

6 recordsLinked to original sources

arXiv2026

Gravitationally Induced Entanglement of Matter in Quadratic Curvature Gravity and Constraints on Ghost Mass

We investigate gravitationally generated entanglement in two quantum harmonic oscillators induced by quadratic (Stelle) gravity, including corrections up to $1.5$ post-Newtonian order. Starting from the quadratic action, we derive the effective two-body Hamiltonian for two harmonically trapped masses, incorporating the contributions of the massive spin-$2$ ghost ($m_2$) and massive spin-$0$ ($m_0$) degrees of freedom of the gravitational field. For two quantised oscillators prepared in their ground state, we compute the von Neumann and Rényi entropies of the reduced state and identify a frequency at which the gravitationally-induced entanglement vanishes due to cancellation between relativistic momentum squeezing and quantum-delocalisation-induced position squeezing. We further analyze the cancellation frequency and derive the approximate constraint $m_0 < \sqrt[3]{4}\, m_2$ for the spin-$2$ and spin-$0$ modes. This relation follows from demanding a stable harmonic oscillator description. Finally, we study gravitationally-induced concurrence in a non-Gaussian setup and show how quadratic gravity modifies the entanglement generated between two spatial superpositions. The concurrence can approach $\mathcal{O}(1)$ for certain choices of mass, spatial superposition, particle distance, and spin-$2$ and spin-$0$ modes. The concurrence will deviate from Newtonian gravity at certain particle separations, depending on the energy of the spin-$2$ and spin-$0$ modes. For example, spin modes as low as $0.0197$ eV become distinguishable from Newtonian gravity at a distance $d \sim 40 μ$m. This allows us to constrain the spin-$2$ and spin-$0$ masses in experiments.

quant-ph↗

arXiv2026

Gravitational waves from the early universe

Even though different models could already be constrained using CMB data, these models remained unconstrained at higher frequency scales, and, therefore, the knowledge of new physics at these scales remained limited, relying on theoretical assumptions and extrapolations. Recently, however, we experienced the advent of gravitational-wave and multi-messenger astronomy, including the outstanding detections by the LIGO-Virgo collaboration and the searches for Hellings-Downs correlations in pulsar timing data. Over the next decades, ongoing and future collaborations will explore different frequency ranges of the gravitational wave spectrum, granting access to regimes inaccessible by the CMB and collider experiments. These include ground-based, space-borne, and pulsar timing array searches for gravitational waves. By comparing their data with model-dependent gravitational-wave predictions, we can unprecedentedly constrain or eliminate different models or even discover new physics. In these lecture notes, as an entrance door for graduate students, we focus on how we can search for a cosmological background of gravitational waves and how this can be used to probe cosmology and beyond-Standard-Model physics. For this purpose, we review the formalism of gravitational waves in General Relativity, introduce stochastic background gravitational waves, and derive the Hellings-Downs correlation for pulsar timing array searches. We comment on detection efforts and present some of the most important cosmological sources that could produce such a background. These lecture notes were inspired by the course "Gravitational Waves from the Early Universe" given at the 27th W.E. Heraeus "Saalburg" Summer School 2021 by Valerie Domcke.

astro-ph.CO↗

arXiv2026

The Hamiltonian for an atom interacting with gravitational waves

Building on the relativistic Hamiltonian of Sonnleitner and Barnett arXiv:1806.00234 and its post-Newtonian extensions by Schwartz and Giuilini arXiv:1908.06929, we investigate composite atomic systems in dynamical gravitational backgrounds. Using a local inertial frame and a perturbed Minkowski metric, we derive curvature-dependent corrections to both center-of-mass and internal Hamiltonians for atoms interacting with weak gravitational waves. The resulting Hamiltonian contains distinct curvature couplings modifying the internal potential and affecting the center-of-mass dynamics. These contributions imply that internal-energy variations do not always reduce to mass renormalization and can induce genuine forces due to changes in momentum. The initial research was motivated by anomalous friction-like forces emerging in quantum optics, and clarified that the anomalous forces are mere relativistic corrections from mass-energy equivalence. Our results suggest that, with increasingly sensitive detectors, additional forces from gravitational wave interactions may become visible in future experiments.

gr-qc↗

arXiv2025

Causal consistency requirements for gravity-induced entanglement in near-relativistic systems with internal energy

We reconsider a thought experiment that employs the entanglement of the gravitational field with position space quantum states as a means for faster-than-light signaling. We present a protocol that includes the excitation to a higher internal energy level to increase sensitivity to gravitational phase shifts. We report that the explanations why previous versions of the thought experiment remain causally consistent are insufficient to avoid any possibility for faster-than-light signals in this case. An alternative resolution to prevent faster-than-light signaling is most reasonably the requirement for a (near) relativistic treatment. One such effect could be a decoherence channel unobserved in a nonrelativistic treatment.

quant-ph↗

arXiv2024

Environmental gravitational decoherence with higher derivative theory

We discuss the decoherence in a quantum system induced by interaction with gravitational degrees of freedom that are part of a higher derivative theory. The deformation of a mass distribution due to gravitational waves acquires naturally a mass quadrupole moment. This adds higher derivative dynamics of the quadrupole moment to the unitary evolution of the system, where the quadrupole moment oscillates with the gravitational frequencies following a higher derivative theory. The consequence of higher derivatives in the dynamics is that the system is described by four canonical variables. This departure from the usual particle position and momentum operators gives an entirely different interpretation of the decoherence basis. This model focuses on the open dynamics of the quadrupole moment, rather than on individual particles. As such, a short example is given to utilize quadrupole measurements to probe gravitational decoherence and noise. We first derive a Langevin equation for a lower derivative model and show how higher derivatives naturally emerge on the boundary. A quantum master equation is derived for the emerging quadrupole moment, considering that the environment is a higher derivative theory of gravity.

gr-qc↗

arXiv2024

Thermodynamics and dynamics of coupled complex SYK models

It has been known that the large-$q$ complex SYK model falls under the same universality class as that of van der Waals (mean-field) and saturates the Maldacena-Shenker-Stanford bound, both features shared by various black holes. This makes the SYK model a useful tool in probing the fundamental nature of quantum chaos and holographic duality. This work establishes the robustness of this shared universality class and chaotic properties for SYK-like models by extending to a system of coupled large-$q$ complex SYK models of different orders. We provide a detailed derivation of thermodynamic properties, specifically the critical exponents for an observed phase transition, as well as dynamical properties, in particular the Lyapunov exponent, via the out-of-time correlator calculations. Our analysis reveals that, despite the introduction of an additional scaling parameter through interaction strength ratios, the system undergoes a continuous phase transition at low temperatures, similar to that of the single SYK model. The critical exponents align with the Landau-Ginzburg (mean-field) universality class, shared with van der Waals gases and various AdS black holes. Furthermore, we demonstrate that the coupled SYK system remains maximally chaotic in the large-$q$ limit at low temperatures, adhering to the Maldacena-Shenker-Stanford bound, a feature consistent with the single SYK model. These findings establish robustness and open avenues for broader inquiries into the universality and chaos in complex quantum systems. We provide a detailed outlook for future work by considering the "very" low-temperature regime, where we discuss relations with the Hawking-Page phase transition observed in the holographic dual black holes. We present preliminary calculations and discuss the possible follow-ups that might be taken to make the connection robust.

hep-th↗