arXiv subjects

Matteo Carlesso

Publications and source records attributed to Matteo Carlesso.

44 records · Page 3Linked to original sources

arXiv2019

Testing Continuous Spontaneous Localization with Fermi liquids

Collapse models describe phenomenologically the quantum-to-classical transition by adding suitable nonlinear and stochastic terms to the Schroedinger equation, thus (slightly) modifying the dynamics of quantum systems. Experimental bounds on the collapse parameters have been derived from various experiments involving a plethora of different systems, from single atoms to gravitational wave detectors. Here, we give a comprehensive treatment of the Continuous Spontaneous Localization (CSL) model, the most studied among collapse models, for Fermi liquids. We consider both the white and non-white noise case. Application to various astrophysical sources is presented.

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arXiv2018

Colored collapse models from the non-interferometric perspective

Models of spontaneous wave function collapse describe the quantum-to-classical transition by assuming a progressive breakdown of the superposition principle when the mass of the system increases, providing a well-defined phenomenology in terms of a non-linearly and stochastically modified Schrodinger equation, which can be tested experimentally. The most popular of such models is the Continuous Spontaneous Localization (CSL) model: in its original version, the collapse is driven by a white noise, and more recently, generalizations in terms of colored noises, which are more realistic, have been formulated. We will analyze how current non-interferometric tests bound the model, depending on the spectrum of the noise. We will find that low frequency purely mechanical experiments provide the most stable and strongest bounds.

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arXiv2018

Non-interferometric test of the Continuous Spontaneous Localization model based on rotational optomechanics

The Continuous Spontaneous Localization (CSL) model is the best known and studied among collapse models, which modify quantum mechanics and identify the fundamental reasons behind the unobservability of quantum superpositions at the macroscopic scale. Albeit several tests were performed during the last decade, up to date the CSL parameter space still exhibits a vast unexplored region. Here, we study and propose an unattempted non-interferometric test aimed to fill this gap. We show that the angular momentum diffusion predicted by CSL heavily constrains the parametric values of the model when applied to a macroscopic object.

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arXiv2018

Multilayer test masses to enhance the collapse noise

Recently, a non-thermal excess noise, compatible with the theoretical prediction provided by collapse models, was measured in a millikelvin nanomechanical cantilever experiment [Vinante et al., Phys. Rev. Lett. 119, 110401 (2017)]. We propose a feasible implementation of the cantilever experiment able to probe such a noise. The proposed modification, completely within the grasp of current technology and readily implementable also in other type of mechanical non-interferometric experiments, consists in substituting the homogeneous test mass with one composed of different layers of different materials. This will enhance the action of a possible collapse noise above that given by standard noise sources.

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arXiv2017

When Cavendish meets Feynman: A quantum torsion balance for testing the quantumness of gravity

We propose a thought experiment, based on a mechanism that is reminiscent of Cavendish's torsion balance, to investigate the possible quantum nature of the gravitational field generated by the quantum superposition state of a massive system. Our proposal makes use of the dynamics of a ultra-stable optically levitated nanomechanical rotor endowed with a spin to generate a quantum angular superposition that is then tested through standard Ramsey-like scheme. Gravity manifests itself as an effective decoherence mechanism, whose strength is different-and, as we show, appreciable-in the classical and quantum case. By incorporating both the source for decoherence and the mechanism to probe it, the experiment that we propose allows for a much reduced degree of control and dynamical engineering.

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arXiv2017

Adjoint master equation for Quantum Brownian Motion

Quantum brownian motion is a fundamental model for a proper understanding of open quantum systems in different contexts such as chemistry, condensed matter physics, bio-physics and opto- mechamics. In this paper we propose a novel approach to describe this model. We provide an exact and analytic equation for the time evolution of the operators, and we show that the corresponding equation for the states is equivalent to well-known results in literature. The dynamics is expressed in terms of the spectral density, regardless the strength of the coupling between the system and the bath. Our allows to compute the time evolution of physically relevant quantities in a much easier way than previous formulations allow to. An example is explicitly studied.

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arXiv2016

Quantum-limited estimation of continuous spontaneous localization

We apply the formalism of quantum estimation theory to extract information about potential collapse mechanisms of the continuous spontaneous localisation (CSL) form. In order to estimate the strength with which the field responsible for the CSL mechanism couples to massive systems, we consider the optomechanical interaction between a mechanical resonator and a cavity field. Our estimation strategy passes through the probing of either the state of the oscillator or that of the electromagnetic field that drives its motion. In particular, we concentrate on all-optical measurements, such as homodyne and heterodyne measurements. We also compare the performances of such strategies with those of a spin-assisted optomechanical system, where the estimation of the CSL parameter is performed through time-gated spin-like measurements.

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arXiv2016

Decoherence due to gravitational time dilation: analysis of competing decoherence effects

Recently, a static gravitational field, such as that of the Earth, was proposed as a new source of decoherence [1]. We study the conditions under which it becomes the dominant decoherence effect in typical interferometric experiments. The following competing sources are considered: spontaneous emission of light, absorption, scattering with the thermal photons and collisions with the residual gas. We quantify all these effects. As we will see, current experiments are off by several orders of magnitude. New ideas are needed in order to achieve the necessary requirements: having as large as system as possible, to increase gravitational decoherence, cool it and isolated well enough to reduce thermal and collisional decoherence, and resolve very small distances.

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