On the spontaneous emission of electromagnetic radiation in the CSL model

Spontaneous photon emission in the Continuous Spontaneous Localization (CSL) model is studied one more time. In the CSL model each particle interacts with a noise field that induces the collapse of its wave function. As a consequence of this interaction, when the particle is electrically charged, it radiates. As discussed in [1], the formula for the emission rate, to first perturbative order, contains two terms: One is proportional to the Fourier component of the noise field at the same frequency as that of the emitted photon and one is proportional to the zero Fourier component of the noise field. As discussed in previous works, this second term seems unphysical. In [1], it was shown that the unphysical term disappears when the noises is confined to a bounded region and the final particle's state is a wave packet. Here we investigate the origin of the unphysical term and why it vanishes according to the previous prescription. For this purpose, the electrodynamic part of the equation of motion is solved exactly while the part due to the noise is treated perturbatively. We show that the unphysical term is connected to exponentially decaying function of time which dies out in the large time limit, however, approximates to 1 in the first perturbative order in the electromagnetic field.Comment: 10 pages, 1 figure, LaTe

Entangling macroscopic diamonds at room temperature: Bounds on the continuous-spontaneous-localization parameters

A recent experiment [K. C. Lee et al., Science 334, 1253 (2011)] succeeded in detecting entanglement between two macroscopic specks of diamonds, separated by a macroscopic distance, at room temperature. This impressive results is a further confirmation of the validity of quantum theory in (at least parts of) the mesoscopic and macroscopic domain, and poses a challenge to collapse models, which predict a violation of the quantum superposition principle, which is the bigger the larger the system. We analyze the experiment in the light of such models. We will show that the bounds placed by experimental data are weaker than those coming from matter-wave interferometry and non-interferometric tests of collapse models.Comment: 7 pages, 3 figures, v2: close to the published version, LaTe

Are collapse models testable with quantum oscillating systems? The case of neutrinos, kaons, chiral molecules

Collapse models provide a theoretical framework for understanding how classical world emerges from quantum mechanics. Their dynamics preserves (practically) quantum linearity for microscopic systems, while it becomes strongly nonlinear when moving towards macroscopic scale. The conventional approach to test collapse models is to create spatial superpositions of mesoscopic systems and then examine the loss of interference, while environmental noises are engineered carefully. Here we investigate a different approach: We study systems that naturally oscillate --creating quantum superpositions-- and thus represent a natural case-study for testing quantum linearity: neutrinos, neutral mesons, and chiral molecules. We will show how spontaneous collapses affect their oscillatory behavior, and will compare them with environmental decoherence effects. We will show that, contrary to what previously predicted, collapse models cannot be tested with neutrinos. The effect is stronger for neutral mesons, but still beyond experimental reach. Instead, chiral molecules can offer promising candidates for testing collapse models.Comment: accepted by NATURE Scientific Reports, 12 pages, 1 figures, 2 table

Quantum Spectrometry for Arbitrary Noise

We present a technique for recovering the spectrum of a non-Markovian bosonic bath and/or non-Markovian noises coupled to a harmonic oscillator. The treatment is valid under the conditions that the environment is large and hot compared to the oscillator, and that its temporal autocorrelation functions are symmetric with respect to time translation and reflection—criteria which we consider fairly minimal. We model a demonstration of the technique as deployed in the experimental scenario of a nanosphere levitated in a Paul trap, and show that it would effectively probe the spectrum of an electric field noise source from 1 0 2 to 1 0 6     Hz with a resolution inversely proportional to the measurement time. This technique may be deployed in quantum sensing, metrology, computing, and in experimental probes of foundational questions

Are Collapse Models Testable via Flavor Oscillations?

Collapse models predict the spontaneous collapse of the wave function, in order to avoid the emergence of macroscopic superpositions. In their mass-dependent formulation they claim that the collapse of any system's wave function depends on its mass. Neutral K, D, B mesons are oscillating systems that are given by Nature as superposition of different mass eigenstates. Thus they are unique and interesting systems to look at, for analyzing the experimental implications of such models, so far in agreement with all known experiments. In this paper we derive - for the single mesons and bipartite entangled mesons - the effect of the mass-proportional CSL collapse model on the dynamics on neutral mesons, including the relativistic effects. We compare the theoretical prediction with experimental data from different accelerator facilities.Comment: 20 pages, RevTe

Density-dependent positive feedbacks buffer aquatic plants from interactive effects of eutrophication and predator loss

Self-facilitation allows populations to persist under disturbance by ameliorating experienced stress. In coastal ecosystems, eutrophication and declines of large predatory fish are two common disturbances that can synergistically impact habitat-forming plants by benefitting ephemeral algae. In theory, density-dependent intraspecific plant facilitation could weaken such effects by ameliorating the amount of experienced stress. Here, we tested whether and how shoot density of a common aquatic plant (Myriophyllum spicatum) alters the response of individual plants to eutrophication and exclusion of large predatory fish, using a 12-week cage experiment in the field. Results showed that high plant density benefitted individual plant performance, but only when the two stressors were combined. Epiphytic algal biomass per plant more than doubled in cages that excluded large predatory fish, indicative of a trophic cascade. Moreover, in this treatment, individual shoot biomass, as well as number of branches, increased with density when nutrients were added, but decreased with density at ambient nutrient levels. In contrast, in open cages that large predatory fish could access, epiphytic algal biomass was low and individual plant biomass and number of branches were unaffected by plant density and eutrophication. Plant performance generally decreased under fertilization, suggesting stressful conditions. Together, these results suggest that intraspecific plant facilitation occurred only when large fish exclusion (causing high epiphyte load) was accompanied by fertilization, and that intraspecific competition instead prevailed when no nutrients were added. As coastal ecosystems are increasingly exposed to multiple and often interacting stressors such as eutrophication and declines of large predatory fish, maintaining high plant density is important for ecosystem-based management.</p

Pityriasis lichenoides: clinical and immunogenetic studies

Type of study:&nbsp;Prevalence study.&nbsp;Objectives:&nbsp;Despite pityriasis lichenoides is an uncommon dermatosis, we observed 12 cases in the last 3 years. By this means, we review clinical and histopathologic findings of all patients with pityriasis lichenoides seen at our Division. Furthermore, since pathogenic features of the disease are unknown, we performed HLA class I and II typings to search for possible immunogenetic markers for pityriasis lichenoides. Methods:&nbsp;Twenty-one patients with biopsy-proven diagnosis of pityriasis lichenoides were evaluated. HLA class I and II antigens were typed using conventional serological procedures.&nbsp;Results:&nbsp;Children and young adults were predominantly affected. Most of the cases were seen in fall and winter time. Typical disseminated lesions were observed more frequently. Both acute and chronic patterns were observed at histology. Compared to controls, the HLA-B17 antigen was overrepresented in patients (P&lt; 0.005). Conclusions:&nbsp;Although pityriasis lichenoides remains a cutaneous disease of undetermined origin, our findings show that the disease is associated with the HLA-B17 antigen. .Modelo de estudo:Estudo de prevalência.&nbsp;Objetivos:&nbsp;Embora a pitiríase liquenóide seja uma dermatose incomum, 12 casos foram por nós observados nos últimos três anos. Assim, neste estudo, avaliamos os perfis clínicos e histopatológicos dos pacientes com pitiríase liquenóide, atendidos na Divisão de Dermatologia. Além disso, tipificamos os antígenos HLA de classes I e II nesses pacientes.Metodologia:&nbsp;Foram estudados 21 pacientes com diagnóstico clínico e histopatológico de pitiríase liquenóide. As tipificações dos antígenos de histocompatibilidade de classes I e II foram realizadas, utilizando-se métodos sorológicos.&nbsp;Resultados:&nbsp;A maioria dos casos ocorreu entre crianças e ou adultos jovens, no outono e inverno. As lesões típicas de forma disseminada foram as mais freqüentes. Os achados histopatológicos mostraram lesões dos tipos agudo e crônico. O antígeno HLA-B17 estava significantemente aumentado nos pacientes em relação aos controles (P&lt;0,005).Conclusões: Embora a etiologia da pitiríase liquenóide não seja conhecida, os achados aqui relatados mostram que o marcador HLA-B17 é prevalente entre os doentes

Unitary unraveling for the dissipative continuous spontaneous localization model: Application to optomechanical experiments

The Continuous Spontaneous Localization (CSL) model strives to describe the quantum-to-classical transition from the viewpoint of collapse models. However, its original formulation suffers from a fundamental inconsistency in that it is explicitly energy non-conserving. Fortunately, a dissipative extension to CSL has been recently formulated that solves such energy-divergence problem. We compare the predictions of the dissipative and non-dissipative CSL models when various optomechanical settings are used, and contrast such predictions with available experimental data, thus building the corresponding exclusion plots