Entanglement dynamics of two mesoscopic objects with gravitational interaction

Nguyen, H. Chau; Bernards, Fabian

doi:10.1140/epjd/e2020-10077-8

Cited by 44 publications

(59 citation statements)

References 35 publications

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“…[2,20,[31][32][33][34][35][36][37]. There have also been noise analysis [38], as well as related independent suggestions [39,40] and paradox resolutions [41,42] which point toward the necessity of gravity to be quantum in nature.…”

Section: Introductionmentioning

confidence: 99%

Locality and entanglement in table-top testing of the quantum nature of linearized gravity

2020

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This paper points out the importance of the assumption of locality of physical interactions, and the concomitant necessity of propagation of an entity (in this case, off-shell quanta-virtual gravitons) between two nonrelativistic test masses in unveiling the quantum nature of linearized gravity through a laboratory experiment. At the outset, we will argue that observing the quantum nature of a system is not limited to evidencing O(h) corrections to a classical theory: it instead hinges upon verifying tasks that a classical system cannot accomplish. We explain the background concepts needed from quantum field theory and quantum information theory to fully appreciate the previously proposed table-top experiments, namely forces arising through the exchange of virtual (off-shell) quanta, as well as local operations and classical communication (LOCC) and entanglement witnesses. We clarify the key assumption inherent in our evidencing experiment, namely the locality of physical interactions, which is a generic feature of interacting systems of quantum fields around us, and naturally incorporate microcausality in the description of our experiment. We also present the types of states the matter field must inhabit, putting the experiment on firm relativistic quantum-field-theoretic grounds. At the end, we use a nonlocal theory of gravity to illustrate how our mechanism may still be used to detect the qualitatively quantum nature of a force when the scale of nonlocality is finite. We find that the scale of nonlocality, including the entanglement entropy production in local and nonlocal gravity, may be revealed from the results of our experiment.

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Section: Introductionmentioning

confidence: 99%

Locality and entanglement in table-top testing of the quantum nature of linearized gravity

2020

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“…A similar proposal was also made in [15]. This has attracted significant interest from the research community [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] and an experimental initiative in creating a macroscopic superposition with the Stern-Gerlach setup [32]. The above proposal has been coined quantum gravity-induced entanglement of masses (QGEM), which exploits the loophole that as local operations and classical communications are unable to entangle the two quantum states if they are not entangled, to begin with, quantum communication is required to generate the entanglement as highlighted in [13].…”

Section: Introductionmentioning

confidence: 71%

“…In particular, we consider how quickly different setups can generate entanglement according to a generalized model of the QGEM experiment and how many measurements would be required to witness that entanglement. We test our findings in the presence of decoherence, furthering the analyses presented in [19][20][21][22].…”

Section: Introductionmentioning

confidence: 88%

“…Our key findings are that the parallel setups [20] of the experiment entangle faster than any other setup considered; in the presence of decoherence, using qudits may be beneficial for the experiment and could even be necessary; we provide an order of magnitude for the number of measurements required to reach a 99.9% level of confidence (about 3.4σ ) for different decoherence rates (up to 0.125 Hz). This paper will proceed as follows.…”

Section: Introductionmentioning

confidence: 88%

“…1. Schematic representation of the experiment, shown here using qubits: (a) the linear setup presented in [14,15,21] and (b) a schematic for the parallel setup initially presented in [20].…”

Section: Introductionmentioning

confidence: 99%

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Qudits for witnessing quantum-gravity-induced entanglement of masses under decoherence

et al. 2021

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Recently, a theoretical and an experimental protocol known as quantum-gravity-induced entanglement of masses (QGEM) has been proposed to test the quantum nature of gravity using two mesoscopic masses, each placed in a superposition of two locations. If after eliminating all nongravitational interactions between them the particles become entangled, one can conclude that the gravitational potential is induced via a quantum mediator, i.e., graviton. In this paper we explore extensions of the QGEM experiment to multidimensional quantum objects and examine a range of different experiment geometries, in order to determine which would generate entanglement faster. We conclude that when a sufficiently high decoherence rate is introduced, multicomponent superpositions can outperform the two-qubit setup. With low decoherence however, and given a maximum distance x between any two spatial states of a superposition, a set of two qubits placed in spatial superposition parallel to one another will outperform all other models given realistic experimental parameters. This is further verified with an experiment simulation, showing that O( 103 ) measurements are required to reject the no-entanglement hypothesis with a parallel-qubit setup without decoherence at a 99.9% confidence level. The number of measurements increases when decoherence is introduced. When the decoherence rate reaches 0.125 Hz, six-dimensional qudits are required as the two-qubit system entanglement cannot be witnessed anymore. However, in this case, O(10 6 ) measurements will be required. One can group the witness operators to measure in order to reduce the number of measurements (up to tenfold). However, this may be challenging to implement experimentally.

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Essential Role of Destructive Interference in the Gravitationally Induced Entanglement

Rostom

2022

Fortschritte der Physik

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The gravitationally induced entanglement is a type of quantum entanglement that can be generated between two mesoscopic particles using their Newtonian gravitational interaction. It has attracted a great deal of attention as a new platform for studying quantum aspects of gravity. The present paper analyzes the gravitationally induced entanglement as a pure interference effect and shows that the entanglement is induced solely by a sign change associated with the destructive quantum interference. It is also shown that when the entanglement is non‐maximal, the preparation for destructive interference for one of the particles can recover a maximum visibility interference pattern for the other particle. Therefore, the non‐maximally entangled state can be extremely effective for experimental testing since it can help in reducing requirements (on masses of the particles and their interaction duration, separation distances and sources) and preserve the information about entanglement at the same time. As a result, the improvement in the signal‐to‐noise ratio is demonstrated and a parameter that determines minimal requirements for experimental testing is defined.

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Entanglement dynamics of two mesoscopic objects with gravitational interaction

Cited by 44 publications

References 35 publications

Locality and entanglement in table-top testing of the quantum nature of linearized gravity

Locality and entanglement in table-top testing of the quantum nature of linearized gravity

Qudits for witnessing quantum-gravity-induced entanglement of masses under decoherence

Essential Role of Destructive Interference in the Gravitationally Induced Entanglement

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