arXiv subjects

Andrea Vinante

Publications and source records attributed to Andrea Vinante.

31 records · Page 2Linked to original sources

arXiv2020

Ferromagnetic Gyroscopes for Tests of Fundamental Physics

A ferromagnetic gyroscope (FG) is a ferromagnet whose angular momentum is dominated by electron spin polarization and that will precess under the action of an external torque, such as that due to a magnetic field. Here we model and analyze FG dynamics and sensitivity, focusing on practical schemes for experimental realization. In the case of a freely floating FG, we model the transition from dynamics dominated by libration in relatively high externally applied magnetic fields, to those dominated by precession at relatively low applied fields. Measurement of the libration frequency enables in situ measurement of the magnetic field and a technique to reduce the field below the threshold for which precession dominates the FG dynamics. We note that evidence of gyroscopic behavior is present even at magnetic fields much larger than the threshold field below which precession dominates. We also model the dynamics of an FG levitated above a type-I superconductor via the Meissner effect, and find that for FGs with dimensions larger than about 100 nm the observed precession frequency is reduced compared to that of a freely floating FG. This is akin to negative feedback that arises from the distortion of the field from the FG by the superconductor. Finally we assess the sensitivity of an FG levitated above a type-I superconductor to exotic spin-dependent interactions under practical experimental conditions, demonstrating the potential of FGs for tests of fundamental physics.

quant-ph↗

arXiv2020

Zel'dovich amplification in a superconducting circuit

Zel'dovich proposed that electromagnetic (EM) waves with angular momentum reflected from a rotating metallic, lossy cylinder will be amplified. However, we are still lacking a direct experimental EM-wave verification of this fifty-year old prediction due to the challenging conditions in which the phenomenon manifests itself: the mechanical rotation frequency of the cylinder must be comparable with the EM oscillation frequency. Here we propose an experimental approach that solves this issue and is predicted to lead to a measurable Zel'dovich amplification with existing superconducting circuit technology. We design a superconducting circuit with low frequency EM modes that couple through free-space to a magnetically levitated and spinning micro-sphere placed at the center of the circuit. We theoretically estimate the circuit EM mode gain and show that rotation of the micro-sphere can lead to experimentally observable amplification, thus paving the way for the first EM-field experimental demonstration of Zel'dovich amplification.

physics.class-ph↗

arXiv2019

Acceleration sensing with magnetically levitated oscillators above a superconductor

We experimentally demonstrate stable trapping of a permanent magnet sphere above a lead superconductor, in vacuum pressures of $4 \times 10^{-8}$~mbar. The levitating magnet behaves as a harmonic oscillator, with frequencies in the 4-31~Hz range detected, and shows promise to be an ultrasensitive acceleration sensor. We directly apply an acceleration to the magnet with a current carrying wire, which we use to measure a background noise of $\sim 10^{-10} \ \text{m}/\sqrt{\text{Hz}}$ at 30.75~Hz frequency. With current experimental parameters, we find an acceleration sensitivity of $S_a^{1/2} = 1.2 \pm 0.2 \times 10^{-10} \ \text{g}/\sqrt{\text{Hz}}$, for a thermal noise limited system. By considering a 300~mK environment, at a background helium pressure of $1 \times 10^{-10}$~mbar, acceleration sensitivities of $S_a^{1/2} \sim 3 \times 10^{-15} \ \text{g}/\sqrt{\text{Hz}}$ could be possible with ideal conditions and vibration isolation. To feasibly measure with such a sensitivity, feedback cooling must be implemented.

physics.app-ph↗

arXiv2019

New avenues for testing collapse models

We present a concise outlook on future experimental tests of spontaneous wave function collapse models. We discuss tests based on force noise measurements in ultrasensitive mechanical systems, spontaneous heating in ultracold solid matter and atoms, matter-wave interferometry, and ultrahigh precision measurements.

quant-ph↗

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.

quant-ph↗

arXiv2018

Testing spontaneous collapse through bulk heating experiments: estimate of the background noise

Models of spontaneous wave function collapse predict a small heating rate for a bulk solid, as a result of coupling to the noise field that causes collapse. This rate is small enough that ambient radioactivity and cosmic ray flux on the surface of the earth can mask the heating due to spontaneous collapse. In this paper we estimate the background noise due to gamma-radiation and cosmic ray muon flux, at different depths. We demonstrate that a low-temperature underground experiment at a depth of about 6.5 km.w.e. would have a low enough background to allow detection of bulk heating for a collapse rate $λ$ of $10^{-16}$ s$^{-1}$ using presently available technology.

quant-ph↗

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.

quant-ph↗

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.

quant-ph↗

arXiv2018

Heating Through Phonon Excitation Implied by Collapse Models

We calculate the rate of heating through phonon excitation implied by the noise postulated in mass-proportional-coupled collapse models, for a general noise power spectrum. For white noise with reduction rate $λ$, the phonon heating rate reduces to the standard formula, but for non-white noise with power spectrum $λ(ω)$, the rate $λ$ is replaced by $λ_{\rm eff}=\frac{2}{3 π^{3/2}} \int d^3w e^{-\vec w^2} \vec w^2 λ(ω_L(\vec w/r_c))$, with $ω_L(\vec q)$ the longitudinal acoustic phonon frequency as a function of wave number $\vec q$, and with $r_C$ the noise correlation length. Hence if the noise power spectrum is cut off below $ω_L(|\vec q| \sim r_c^{-1})$, the heating rate is sharply reduced.

quant-ph↗

arXiv2016

Search for light scalar Dark Matter candidate with AURIGA detector

A search for a new scalar field, called moduli, has been performed using the cryogenic resonant-mass AURIGA detector. Predicted by string theory, moduli may provide a significant contribution to the dark matter (DM) component of our universe. If this is the case, the interaction of ordinary matter with the local DM moduli, forming the Galaxy halo, will cause an oscillation of solid bodies with a frequency corresponding to the mass of moduli. In the sensitive band of AURIGA, some $100\,\mathrm{Hz}$ at around $1\,\mathrm{kHz}$, the expected signal, with a $Q=\tfrac{\triangle f}{f}\sim10^{6}$, is a narrow peak, $\triangle f\sim1\,\mathrm{mHz}$. Here the detector strain sensitivity is $h_{s}\sim2\times10^{-21}\,\mathrm{Hz^{-1/2}}$, within a factor of $2$. These numbers translate to upper limits at $95\%\,C.L.$ on the moduli coupling to ordinary matter $d_{e}\lesssim10^{-5}$ around masses $m_ϕ=3.6\cdot10^{-12}\,\mathrm{eV}$, for the standard DM halo model with $ρ_{DM}=0.3\,\mathrm{GeV/cm^{3}}$.

hep-ex↗

arXiv2016

Bounds on collapse models from cold-atom experiments

The spontaneous localization mechanism of collapse models induces a Brownian motion in all physical systems. This effect is very weak, but experimental progress in creating ultracold atomic systems can be used to detect it. In this paper, we considered a recent experiment [1], where an atomic ensemble was cooled down to picokelvins. Any Brownian motion induces an extra increase of the position variance of the gas. We study this effect by solving the dynamical equations for the Continuous Spontaneous Localizations (CSL) model, as well as for its non-Markovian and dissipative extensions. The resulting bounds, with a 95% of confidence level, are beaten only by measurements of spontaneous X-ray emission and by experiments with cantilever (in the latter case, only for rC > 10^(-7) m, where rC is one of the two collapse parameters of the CSL model). We show that, contrary to the bounds given by X-ray measurements, non-Markovian effects do not change the bounds, for any reasonable choice of a frequency cutoff in the spectrum of the collapse noise. Therefore the bounds here considered are more robust. We also show that dissipative effects are unimportant for a large spectrum of temperatures of the noise, while for low temperatures the excluded region in the parameter space is the more reduced, the lower the temperature.

quant-ph↗

arXiv2014

Superconducting inductive displacement detection of a microcantilever

We demonstrate a superconducting inductive technique to measure the displacement of a micromechanical resonator. In our scheme, a type I superconducting microsphere is attached to the free end of a microcantilever and approached to the loop of a dc Superconducting Quantum Interference Device (SQUID) microsusceptometer. A local magnetic field as low as 100 $μ$T, generated by a field coil concentric to the SQUID, enables detection of the cantilever thermomechanical noise at $4.2$ K. The magnetomechanical coupling and the magnetic spring are in good agreement with image method calculations assuming pure Meissner effect. These measurements are relevant to recent proposals of quantum magnetomechanics experiments based on levitating superconducting microparticles.

cond-mat.mes-hall↗

arXiv2013

Feedback-enhanced parametric squeezing of mechanical motion

We present a single-quadrature feedback scheme able to overcome the conventional 3 dB limit on parametric squeezing. The method is experimentally demonstrated in a micromechanical system based on a cantilever with a magnetic tip. The cantilever is detected at low temperature by a SQUID susceptometer, while parametric pumping is obtained by modulating the magnetic field gradient at twice the cantilever frequency. A maximum squeezing of 11.5 dB and 11.3 dB is observed, respectively in the response to a sinusoidal test signal and in the thermomechanical noise. The maximum squeezing factor is limited only by the maximum achievable parametric modulation. The proposed technique can be used to squeeze one quadrature of a mechanical resonator below the quantum noise level, even without the need for a quantum limited detector.

cond-mat.mes-hall↗