13 results found
Qvarfort S, Plato ADK, Bruschi DE, et al., 2021, Optimal estimation of time-dependent gravitational fields with quantum optomechanical systems, PHYSICAL REVIEW RESEARCH, Vol: 3
Paige AJ, Plato ADK, Kim MS, 2020, Classical and nonclassical time dilation for quantum clocks, Physical Review Letters, Vol: 124, Pages: 160602-1-160602-6, ISSN: 0031-9007
Proper time, ideal clocks, and boosts are well understood classically, but subtleties arise in quantum physics. We show that quantum clocks set in motion via momentum boosts do not witness classical time dilation. However, using velocity boosts we find the ideal behavior in both cases, where the quantum clock and classical observer are set in motion. Without internal state-dependent forces additional effects arise. As such, we derive observed frequency shifts in ion trap atomic clocks, indicating a small additional shift, and also show the emergence of nonideal behavior in a theoretical clock model.
Armata F, Latmiral L, Plato ADK, et al., 2017, Quantum limits to gravity estimation with optomechanics, Physical Review A, Vol: 96, ISSN: 1050-2947
We present a table-top quantum estimation protocol to measure the gravitational acceleration g by using an optomechanical cavity. In particular, we exploit the nonlinear quantum light-matter interaction between an optical field and a massive mirror acting as mechanical oscillator. The gravitational field influences the system dynamics affecting the phase of the cavity field during the interaction. Reading out such a phase carried by the radiation leaking from the cavity, we provide an estimate of the gravitational acceleration through interference measurements. Contrary to previous studies, having adopted a fully quantum description, we are able to propose a quantum analysis proving the ultimate bound to the estimability of the gravitational acceleration and verifying optimality of homodyne detection. Noticeably, thanks to the light-matter decoupling at the measurement time, no initial cooling of the mechanical oscillator is demanded in principle.
Plato ADK, Hughes CN, Kim MS, 2016, Gravitational effects in quantum mechanics, Contemporary Physics, Vol: 57, Pages: 477-495, ISSN: 1366-5812
To date, both quantum theory and Einstein’s theory of general relativity have passed every experimental test in their respective regimes. Nevertheless, almost since their inception, there has been debate surrounding whether they should be unified, and by now, there exists strong theoretical arguments pointing to the necessity of quantising the gravitational field. In recent years, a number of experiments have been proposed which, if successful, should give insight into features at the Planck scale. Here, we review some of the motivations, from the perspective of semi-classical arguments, to expect new physical effects at the overlap of quantum theory and general relativity. We conclude with a short introduction to some of the proposals being made to facilitate empirical verification.
Venkataraman V, Plato ADK, Tufarelli T, et al., 2015, Affecting non-Markovian behaviour by changing bath structures (vol 47, 015501, 2014), JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, Vol: 48, ISSN: 0953-4075
Venkataraman V, Plato ADK, Tufarelli T, et al., 2014, Affecting non-Markovian behaviour by changing bath structures, JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, Vol: 47, ISSN: 0953-4075
Plato ADK, Dahlsten OC, Plenio MB, 2008, Random circuits by measurements on weighted graph states, PHYSICAL REVIEW A, Vol: 78, ISSN: 1050-2947
Evans TS, ADK P, You T, 2008, Are Copying and Innovation Enough?, The European Consortium for Mathematics in Industry 2008 (ECMI 2008), Publisher: Springer, Pages: 825-831
Exact analytic solutions and various numerical results for the rewiring ofbipartite networks are discussed. An interpretation in terms of copying andinnovation processes make this relevant in a wide variety of physical contexts.These include Urn models and Voter models, and our results are also relevant tosome studies of Cultural Transmission, the Minority Game and some models ofecology.
Evans TS, Plato ADK, 2008, Network Rewiring Models, Networks and Heterogeneous Media, Vol: 3, Pages: 221-238
Recently we showed that a simple model of network rewiring could be solved exactly for any time and any parameter value. We also showed that this model can be recast in terms of several well known models of statistical physics such as Urn model and the Voter model. We also noted that it has been applied to a wide range of problems. Here we consider various generalisations of this model and include some new exact results.
Evans TS, Plato ADK, 2007, Exact solution for the time evolution of network rewiring models, PHYSICAL REVIEW E, Vol: 75, ISSN: 2470-0045
Evans TS, Plato ADK, 2006, Exact Solutions for Models of Cultural Transmission and Network Rewiring, The European Conference on Complex Systems' 06
Plato ADK, Rätzel D, Wan C, Enhanced Gravitational Entanglement in Modulated Optomechanics
The role of entanglement in determining the non-classicality of a giveninteraction has gained significant traction over the last few years. Inparticular, as the basis for new experimental proposals to test the quantumnature of the gravitational field. Here we show that the rate of gravitymediated entanglement between two otherwise isolated optomechanical systems canbe significantly increased by modulating the optomechanical coupling. This ismost pronounced for low mass, high frequency systems - convenient for reachingthe quantum regime - and can lead to improvements of several orders ofmagnitude, as well as a broadening of the measurement window. Nevertheless,significant obstacles still remain. In particular, we find that modulationsincrease decoherence effects at the same rate as the entanglement improvements.This adds to the growing evidence that the constraint on noise (acting on theposition d.o.f) depends only on the particle mass, separation, and temperatureof the environment and cannot be improved by novel quantum control. Finally, wehighlight the close connection between the observation of quantum correlationsand the limits of measurement precision derived via the Cram\'er-Rao Bound. Animmediate consequence is that probing superpositions of the gravitational fieldplaces similar demands on detector sensitivity as entanglement verification.
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