1,721,033 research outputs found
Correlated random walks caused by dynamical wavefunction collapse
No full textWavefunction collapse models modify Schrödinger’s equation so that it describes the collapse of a superposition of macroscopically distinguishable states as a dynamical process. This provides a basis for the resolution of the quantum measurement problem. An additional generic consequence of the collapse mechanism is that it causes particles to exhibit a tiny random diffusive motion. Here it is shown that for the continuous spontaneous localization (CSL) model—one of the most well developed collapse models—the diffusions of two sufficiently nearby particles are positively correlated. An experimental test of this effect is proposed in which random displacements of pairs of free nanoparticles are measured after they have been simultaneously released from nearby traps. The experiment must be carried out at sufficiently low temperature and pressure in order for the collapse effects to dominate over the ambient environmental noise. It is argued that these constraints can be satisfied by current technologies for a large region of the viable parameter space of the CSL model. The effect disappears as the separation between particles exceeds the CSL length scale. The test therefore provides a means of bounding this length scale
Non-interferometric test of the continuous spontaneous localization model based on rotational optomechanics
Full text linkThe 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
Prospects for near-field interferometric tests of collapse models
No full textNear-field interferometry with large dielectric nanoparticles opens the way to test fundamental modifications of standard quantum mechanics at an unprecedented level. We showcase the capabilities of such platform, in a state-of-the-art ground-based experimental setup, to set stringent bounds on the parameter space of collapse models and highlight the future perspectives for this class of experiments
Talbot-Lau effect beyond the point-particle approximation
Full text linkRecent progress in matter-wave interferometry aims to directly probe the quantum properties of matter on ever increasing scales. However, in order to perform interferometric experiments with massive mesoscopic objects, taking into account the constraints on the experimental setups, the pointlike-particle approximation needs to be cast aside. In this work, we consider near-field interferometry based on the Talbot effects with a single optical grating for large spherical particles beyond the point-particle approximation. We account for the suppression of the coherent grating effect and, at the same time, the enhancement of the decoherence effects due to scattering and absorption of grating photons
Probing modified gravity with magnetically levitated resonators
Full text linkWe present an experimental procedure, based on Meissner effect levitation of neodymium ferromagnets, as a method of measuring the gravitational interactions between milligram masses. The scheme consists of two superconducting lead traps, with a magnet levitating in each trap. The levitating magnets behave as harmonic oscillators and, by carefully driving the motion of one magnet on resonance with the other, we find that it should easily be possible to measure the gravitational field produced by a 4 mg sphere, with the gravitational attraction from masses as small as 30 μg predicted to be measurable within a realistic measurement time frame. We apply this acceleration sensitivity to one concrete example and show the abilities of testing models of modified Newtonian dynamics
Testing the quantum superposition principle in the frequency domain
Full text linkWe study how photon emission of a two-level system is modified if the superposition principle is violated. We solve the relevant equations of motion. We quantify the magnitude of the new spectral effects for relevant collapse models to illustrate our theoretical results. We show how these effects can be distinguished from those of standard environmental decoherence. We apply our result to physically interesting systems and suggest that accurate-enough spectroscopic experiments are within reach with current technology
Testing the gravitational field generated by a quantum superposition
Full text linkWhat gravitational field is generated by a massive quantum system in a spatial superposition? Despite decades of intensive theoretical and experimental research, we still do not know the answer. On the experimental side, the difficulty lies in the fact that gravity is weak and requires large masses to be detectable. However, it becomes increasingly difficult to generate spatial quantum superpositions for increasingly large masses, in light of the stronger environmental effects on such systems. Clearly, a delicate balance between the need for strong gravitational effects and weak decoherence should be found. We show that such a trade off could be achieved in an optomechanics scenario that allows to witness whether the gravitational field generated by a quantum system in a spatial superposition is in a coherent superposition or not. We estimate the magnitude of the effect and show that it offers perspectives for observability
Creation of a black hole bomb instability in an electromagnetic system
No full textThe amplification and generation of electromagnetic radiation by a rotating metallic or lossy cylinder, first proposed by Zel’dovich in the 1970s, is closely linked to quantum friction, energy extraction from rotating black holes, and runaway mechanisms such as black hole bombs. Although advances such as acoustic analogs of the Zel’dovich effect and the observation of negative resistance in low-frequency electromagnetic models have been reported, genuine positive signal gain, spontaneous emission of electromagnetic waves, and runaway amplification have not previously been verified. Here, we provide the first experimental demonstration that a mechanically rotating metallic cylinder acts as an amplifier of a rotating electromagnetic field mode. Moreover, when combined with a low-loss resonator, the system becomes unstable and operates as a generator seeded only by noise. The exponential runaway amplification of spontaneously generated electromagnetic modes is observed, establishing the electromagnetic analog of the Press-Teukolsky black hole bomb and paving the way to experimental tests of quantum friction from vacuum fluctuations
Slow beams of massive molecules
No full textSlow beams of neutral molecules are of great interest for a wide range of applications, from cold chemistry through precision measurements to tests of the foundations of quantum mechanics. We report on the quantitative observation of thermal beams of perfluorinated macromolecules with masses up to 6000?amu, reaching velocities down to 11?m/s. Such slow, heavy and neutral molecular beams are of importance for a new class of experiments in matter-wave interferometry and we also discuss the requirements for further manipulation and cooling schemes with molecules in this unprecedented mass range. <br/
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