The constraints of post-quantum classical gravity

Oppenheim, Jonathan; Weller-Davies, Zachary

doi:10.1007/jhep02(2022)080

Cited by 26 publications

(62 citation statements)

References 61 publications

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“…A detailed study of the conservation laws and symmetries present in the hybrid dynamics is performed in Ref. [53].…”

Section: Main Features Of Hybrid Dynamics In Qubit Toy Modelsmentioning

confidence: 99%

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Objective trajectories in hybrid classical-quantum dynamics

Oppenheim,

Sparaciari,

Šoda

et al. 2020

Preprint

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Consistent dynamics which couples classical and quantum degrees of freedom exists, provided it is stochastic. This provides a way to study the back-reaction of quantum fields on space-time which does not suffer from the pathologies of the semi-classical equations. Here we introduce several toy models in which to study hybrid classical-quantum evolution, including a qubit coupled to a particle in a potential, and a quantum harmonic oscillator coupled to a classical one. We present an unravelling approach to calculate the dynamics. Unlike the purely quantum case, the trajectories (or histories) of this unravelling can be unique, conditioned on the classical degrees of freedom. This provides a potential solution to the "measurement problem" of quantum theory; quantum systems become classical because they interact with a genuinely classical field.

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“…A detailed study of the conservation laws and symmetries present in the hybrid dynamics is performed in Ref. [53].…”

Section: Main Features Of Hybrid Dynamics In Qubit Toy Modelsmentioning

confidence: 99%

“…There are various mechanisms one can employ for this purpose which we will briefly mention in the discussion. In the gravitational setting, the more natural question to consider is whether the constraints are preserved in time, a discussion which we reserve for the future [53].…”

Section: Introductionmentioning

confidence: 99%

Objective trajectories in hybrid classical-quantum dynamics

Oppenheim,

Sparaciari,

Šoda

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

Objective trajectories in hybrid classical-quantum dynamics

Oppenheim

Sparaciari

Šoda

et al. 2023

Quantum

Self Cite

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Consistent dynamics which couples classical and quantum degrees of freedom exists, provided it is stochastic. This dynamics is linear in the hybrid state, completely positive and trace preserving. One application of this is to study the back-reaction of quantum fields on space-time which does not suffer from the pathologies of the semi-classical equations. Here we introduce several toy models in which to study hybrid classical-quantum evolution, including a qubit coupled to a particle in a potential, and a quantum harmonic oscillator coupled to a classical one. We present an unravelling approach to calculate the dynamics, and provide code to numerically simulate it. Unlike the purely quantum case, the trajectories (or histories) of this unravelling can be unique, conditioned on the classical degrees of freedom for discrete realisations of the dynamics, when different jumps in the classical degrees of freedom are accompanied by the action of unique operators on the quantum system. As a result, the “measurement postulate'' of quantum theory is not needed; quantum systems become classical because they interact with a fundamentally classical field.

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“…If we want to test whether this EFT is the right model of nature, it behooves us to produce alternative models which would produce some other behavior in such experiments. A variety of models of "classical" gravity coupled to quantum matter have been produced in recent years, for example[53][54][55][56][57][58]. These models are constructed precisely to avoid classic no-go theorems of Weinberg and Polchinski[59,60] by working entirely in the context of linear quantum mechanics; in the next section, we separately discuss ideas about gravitational breakdown of linear time evolution in the quantum state.…”

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confidence: 99%

Snowmass 2021 White Paper: Tabletop experiments for infrared quantum gravity

Carney¹,

Chen²,

Geraci³

et al. 2022

Preprint

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Progress in the quantum readout and control of mechanical devices from single atoms to large masses may enable a first generation of experiments probing the gravitational interaction in the quantum regime, conceivably within the next decade.In this Snowmass whitepaper, we briefly outline the possibilities and challenges facing the realization of these experiments. In particular, we emphasize the need for detailed theories of modifications to the usual effective QFT of gravitons in the infrared regime E/L 3 m Pl / 3 Pl in which these experiments operate, and relations to possible UV completions.

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The constraints of post-quantum classical gravity

Cited by 26 publications

References 61 publications

Objective trajectories in hybrid classical-quantum dynamics

Objective trajectories in hybrid classical-quantum dynamics

Objective trajectories in hybrid classical-quantum dynamics

Snowmass 2021 White Paper: Tabletop experiments for infrared quantum gravity

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