Many experiments have recently been proposed to test whether non-relativistic gravitational interactions can generate entanglement. In this note, I consider the extent to which these experiments can test if the graviton exists. Assuming unitarity and Lorentz invariance of the $S$-matrix, I demonstrate that this "Newtonian entanglement" requires the existence of massless bosons, universally coupled to mass, in the Hilbert space of low-energy scattering states. These bosons could be the usual spin-2 gravitons, but in principle there are other possibilities like spin-0 scalar gravitons. I suggest a concept for a more refined experiment to rule these out. The special role of $d=3+1$ spacetime dimensions and the possibility that unitarity is violated by gravity are highlighted.
We propose an experiment that the entanglement between two macroscopic mirrors suspended at the end of an equal-arm interferometer is destroyed by the noise of gravitons through bremsstrahlung. By calculating the correlation function of the noise, we obtain the decoherence time from the decoherence functional. We estimate that the decoherence time induced by the noise of gravitons in squeezed states stemming from inflation is approximately 20 seconds for 40 km long arms and 40 kg mirrors. Our analysis shows that observation of the decoherence time of quantum entanglement has the potential to d…
We argue that if the Newtonian gravitational field of a body can mediate entanglement with another body, then it should also be possible for the body producing the Newtonian field to entangle directly with on-shell gravitons. Our arguments are made by revisiting a gedankenexperiment previously analyzed by Belenchia et al., which showed that a quantum superposition of a massive body requires both quantized gravitational radiation and local vacuum fluctuations of the spacetime metric in order to avoid contradictions with complementarity and causality. We provide a precise and rigorous descriptio…
When does entanglement through gravity imply gravitons?
Institute for Quantum Optics and Quantum Information (IQOQI) Vienna, Austrian Academy of Sciences（维也纳量子光学与量子信息研究所（奥地利科学院））；Nordita, KTH Royal Institute of Technology and Stockholm University（北欧理论天体物理中心，瑞典皇家理工学院和斯德哥尔摩大学）
Graviton-mediated entanglement due to light bending from a quantum rotor
University College London（伦敦大学学院）；Van Swinderen Institute, University of Groningen（格罗宁根大学范斯温德伦研究所）；Faculty of Mathematics and Physics, University of Ljubljana（卢布尔雅那大学数学与物理学院）
We use entangled multimode coherent states to produce entangled giant graviton states, in the context of gauge/gravity duality. We make a smeared distribution of the entangled multimode coherent states on the circle, or on the five-sphere, in the higher dimensional view. In gauge/gravity duality, we analyze the superposition of giant graviton states, and the entangled pairs of giant graviton states. We map a class of angular distribution functions to unitary operations on the pairs. We also use Young tableau states to construct cat states and qudit states. Various bipartite quantum states invo…
Since Hawking's 1974 discovery, we expect that a black hole formed by collapse will emit radiation and eventually disappear. Closely related to the information loss puzzle is the challenge to define an objective notion of physical entropy which increases throughout this process in a way consistent with unitarity. In recent years, this has been addressed with certain notions of coarse grained entropy. We have suggested instead that physical entropy should be identified with matter-gravity entanglement entropy and that this may offer an explanation of entropy increase both for the black hole col…
If gravitational perturbations are quantized into gravitons in analogy with the electromagnetic field and photons, the resulting graviton interactions should lead to an entangling interaction between massive objects. We suggest a test of this prediction. To do this, we introduce the concept of interactive quantum information sensing. This novel sensing protocol is tailored to provable verification of weak dynamical entanglement generation between a pair of systems. We show that this protocol is highly robust to typical thermal noise sources. The sensitivity can moreover be increased both using…
Entanglement generation in a two-body Schrödinger--Newton model
Qilimanjaro Quantum Tech（Qilimanjaro量子科技公司）；ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology（ICFO光子科学研究所，巴塞罗那科学技术研究院）；Astronomical Observatory, Faculty of Physics, Astronomy and Applied Computer Science Jagiellonian University（雅盖隆大学物理、天文学与应用科学学院天文台）；Doctoral School of Exact and Natural Sciences, Jagiellonian University（雅盖隆大学精确与自然科学学院博士项目）；Institute of Theoretical Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University（雅盖隆大学物理、天文学与应用科学学院理论物理研究所）
Gravitationally mediated entanglement of fermionic qubits: from static to dynamical limits
Isfahan University of Technology（伊斯法罕理工大学）；Dipartimento di Fisica e Astronomia “Galileo Galilei” Università di Padova（帕多瓦大学伽利略·伽利莱物理与天文学系）；Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院吴健中量子中心）；INFN, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）；INAF - Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）；Gran Sasso Science Institute（格兰萨索科学研究所）
We focus on two types of coherent states, the coherent states of multi graviton states and the coherent states of giant graviton states, in the context of gauge/gravity correspondence. We conveniently use a phase shift operator and its actions on the superpositions of these coherent states. We find $N$-state Schrodinger cat states which approach the one-row Young tableau states, with fidelity between them asymptotically reaches 1 at large $N$. The quantum Fisher information of these states is proportional to the variance of the excitation energy of the underlying states, and characterizes the …
We compute the area term contribution to black holes' entanglement entropy (using the conical technique) for a class of local or weakly non-local super-renormalizable gravitational theories coupled to matter. For the first time, we explicitly prove that all the beta functions in the proposed theory, except for the cosmological constant, are identically zero in cut-off regularization scheme and not only in dimensional regularization scheme. In particular, we show that there is no divergence quadratic in cut-off and hence there is no contribution to the beta function of the Newton constant. As a…
