Classicality of quantum information processing

Poulin, David

doi:10.1103/physreva.65.042319

Cited by 9 publications

(5 citation statements)

References 33 publications

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“…Specifically by providing an exponential speedup and reduction in resources over classical methods, VCH will provide a way to study phenomena including the quantum-to-classical transition [31,32,38], dynamics of quantum phase transitions [39], quantum biological processes [40], conformational changes [41], and many other complex phenomena that so far have been computationally intractable. In addition, VCH could be applied to study quantum algorithms themselves [42]. In order to highlight such potential applications and examine their resource requirements, we now focus on two of them: the emergence of classical diffusive dynamics in quantum spin systems and the appearance of defined pathways in protein folding.…”

Section: Discussionmentioning

confidence: 99%

Variational consistent histories as a hybrid algorithm for quantum foundations

et al. 2019

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Although quantum computers are predicted to have many commercial applications, less attention has been given to their potential for resolving foundational issues in quantum mechanics. Here we focus on quantum computers’ utility for the Consistent Histories formalism, which has previously been employed to study quantum cosmology, quantum paradoxes, and the quantum-to-classical transition. We present a variational hybrid quantum-classical algorithm for finding consistent histories, which should revitalize interest in this formalism by allowing classically impossible calculations to be performed. In our algorithm, the quantum computer evaluates the decoherence functional (with exponential speedup in both the number of qubits and the number of times in the history) and a classical optimizer adjusts the history parameters to improve consistency. We implement our algorithm on a cloud quantum computer to find consistent histories for a spin in a magnetic field and on a simulator to observe the emergence of classicality for a chiral molecule.

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Section: Discussionmentioning

confidence: 99%

Variational consistent histories as a hybrid algorithm for quantum foundations

et al. 2019

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“…Nonetheless, consistent classical-quantum theories of Newtonian gravity have been studied via continuous measurement and feedback approaches [24][25][26][27], and in [28] using a master equation for classical-quantum dynamics [29][30][31]. These approaches are all mathematically consistent and do not suffer from the problems of the standard semi-classical approach [22,23].…”

Section: Jhep08(2023)163mentioning

confidence: 99%

The weak field limit of quantum matter back-reacting on classical spacetime

Layton,

Oppenheim,

Russo

et al. 2023

J. High Energ. Phys.

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Consistent coupling of quantum and classical degrees of freedom exists so long as there is both diffusion of the classical degrees of freedom and decoherence of the quantum system. In this paper, we derive the Newtonian limit of such classical-quantum (CQ) theories of gravity. Our results are obtained both via the gauge fixing of the recently proposed path integral theory of CQ general relativity and via the CQ master equation approach. In each case, we find the same weak field dynamics. We find that the New-tonian potential diffuses by an amount lower bounded by the decoherence rate into mass eigenstates. We also present our results as an unraveled system of stochastic differential equations for the trajectory of the hybrid classical-quantum state and provide a series of kernels for constructing figures of merit, which can be used to rule out part of the parameter space of classical-quantum theories of gravity by experimentally testing it via the decoherence-diffusion trade-off. We compare and contrast the weak field limit to previous models of classical Newtonian gravity coupled to quantum systems. Here, we find that the Newtonian potential and quantum state change in lock-step, with the flow of time being stochastic.

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“…Quantum information theory studies the transmission and processing of information when information itself is carried by quantum systems and is processed according to the laws of quantum mechanics [5][6][7][8][9]. The recent achievements in this field include the discovery of new ways of information transmission, of secure communications and the performance of some kinds of computation faster than with classical means.…”

Section: Entanglement Theory In Quantum Informationmentioning

confidence: 99%