Resonant Enhancement Research Articles

Resonant Enhancement of Polymer-Cell Optostimulation by a Plasmonic Metasurface.

Organic semiconductors have shown great potential as efficient bioelectronic materials. Specifically, photovoltaic polymers such as the workhorse poly(thiophene) derivatives, when stimulated with visible light, can depolarize neurons and generate action potentials, an effect that has been also employed for rescuing vision in blind rats. In this context, however, the coupling of such materials with optically resonant structures to enhance those photodriven biological effects is still in its infancy. Here, we employ the optical coupling between a nanostructured metasurface and poly(3-hexylthiophene) (P3HT) to improve the bioelectronic effects occurring upon photostimulation at the abiotic-biotic interface. In particular, we designed a spectrally tuned aluminum metasurface that can resonate with P3HT, hence augmenting the effective field experienced by the polymer. In turn, this leads to an 8-fold increase in invoked inward current in cells. This enhanced activation strategy could be useful to increase the effectiveness of P3HT-based prosthetic implants for degenerative retinal disorders.

Design Principles of Responsive Relaxometric 19F Contrast Agents: Evaluation from the Point of View of Relaxation Theory and Experimental Data.

19F magnetic resonance imaging (MRI) is a promising tool in medical diagnostics. An important class of 19F MRI contrast agents is based on paramagnetic resonance enhancement. This effect allows an improvement in sensitivity by increasing the number of scans per unit of time or facilitates the development of responsive contrast agents that are based on changes in relaxation rates as a detection principle. In this work, Bloch-Redfield-Wangsness relaxation theory was used to predict the relaxation properties of existing lanthanoid and transition metal complexes of fluoroorganic ligands and to evaluate several design strategies for responsive contrast agents. Electron-nucleus dipole-dipole, Curie relaxation, and contact interactions were included in the model. Potential significance of chemical shift anisotropy-anisotropic dipolar shielding cross-correlation was discussed. The calculated and experimental results were well aligned. The presented model, along with the optimized field-dependent values of electronic relaxation times, could be used for the preliminary selection of the optimal metal ion for applications in 19F MRI. The results indicate potential advantages of other metal ions in addition to Gd3+ particularly Cu2+, Mn2+, Ni2+, Fe3+, and other lanthanoids as a part of 19F contrast agents.

Midinfrared Optical Manipulation Based on Molecular Vibrational Resonance

Midinfrared light is extensively used for identifying molecules because their characteristic vibrational modes commonly exist in the midinfrared spectral region. In this paper, a midinfrared quantum cascade laser is utilized for sorting silica particles with resonant enhancement of the optical force by exciting their vibrational mode. Silica particles on an evanescent wave drift rapidly along the prism surface, whereas identical-sized polystyrene particles drift at 7--10 times lower speed. We suggest the application of this principle for optical force chromatography in the midinfrared region.

Chemical imaging of cellular ultrastructure by null-deflection infrared spectroscopic measurements

Nearfield spectroscopic imaging techniques can be a powerful tool to map both cellular ultrastructure and molecular composition simultaneously but are currently limited in measurement capability. Resonance enhanced (RE) atomic force microscopy infrared (AFM-IR) spectroscopic imaging offers high-sensitivity measurements, for example, but probe-sample mechanical coupling, nonmolecular optical gradient forces, and noise overwhelm recorded chemical signals. Here, we analyze the key factors limiting AFM-IR measurements and propose an instrument design that enables high-sensitivity nanoscale IR imaging by combining null-deflection measurements with RE sensitivity. Our developed null-deflection scanning probe IR (NDIR) spectroscopic imaging provides ∼24× improvement in signal-to-noise ratio (SNR) compared with the state of the art, enables optimal signal recording by combining cantilever resonance with maximum laser power, and reduces background nonmolecular signals for improved analytical accuracy. We demonstrate the use of these properties for high-sensitivity, hyperspectral imaging of chemical domains in 100-nm-thick sections of cellular acini of a prototypical cancer model cell line, MCF-10A. NDIR chemical imaging enables facile recording of label-free, chemically accurate, high-SNR vibrational spectroscopic data from nanoscale domains, paving the path for routine studies of biomedical, forensic, and materials samples.

Ultrafast Demagnetization Control in Magnetophotonic Surface Crystals.

Magnetic memory combining plasmonics and magnetism is poised to dramatically increase the bit density and energy efficiency of light-assisted ultrafast magnetic storage, thanks to nanoplasmon-driven enhancement and confinement of light. Here we devise a new path for that, simultaneously enabling light-driven bit downscaling, reduction of the required energy for magnetic memory writing, and a subtle control over the degree of demagnetization in a magnetophotonic surface crystal. It features a regular array of truncated-nanocone-shaped Au-TbCo antennas showing both localized plasmon and surface lattice resonance modes. The ultrafast magnetization dynamics of the nanoantennas show a 3-fold resonant enhancement of the demagnetization efficiency. The degree of demagnetization is further tuned by activating surface lattice modes. This reveals a platform where ultrafast demagnetization is localized at the nanoscale and its extent can be controlled at will, rendering it multistate and potentially opening up so-far-unforeseen nanomagnetic neuromorphic-like systems operating at femtosecond time scales controlled by light.

Photophysical properties and aggregation behavior of diethylene glycol substituted pyropheophorbide-a in cationic surfactant solutions

The aggregation behavior of a novel amphiphilic photosensitizer - pyropheophorbide-[Formula: see text] 17-diethylene glycol ester 1 was studied in aqueous and aqueous-organic mixtures by means of steady-state absorption and fluorescence emission spectroscopy. The formation of [Formula: see text]-aggregates with a bathochromic shift of the absorption bands, weak fluorescence and resonance enhancement of the light scattering was observed in the mixed water-organic solvents. Solubilization studies in micellar cationic surfactant solutions of alkyl trimethylammonium bromides (C[Formula: see text]TAB) and alkyl triphenylphosphonium bromides (C[Formula: see text]TPPB) resulted in the most effective stabilization of the fluorescent monomolecular form of 1 in C[Formula: see text]TPPB micelles. It was shown that [Formula: see text]-aggregate formation in submicellar surfactant solutions is the initial stage of the solubilization process, which significantly increases in phosphate buffer medium at pH 7.4. Fluorescence lifetime ([Formula: see text] of 1 in DMSO was found to be 7.4 ns, fluorescence quantum yield - 34% and singlet oxygen quantum yield - 62%. The results obtained indicate the need for further studies of compound 1 solubilized in C[Formula: see text]TPPB micelles as the most promising prototype of the drug formulation for mitochondria-targeted photodynamic therapy of cancer.

Opto-mechanically generated resonant field enhancement

A link between the resonant cumulative field enhancement experienced by a chain of plasmonic nanoparticles in a light field and the orientation of the chain with respect to the field is obtained. We calculate analytically the optical torque and the equilibrium configuration and we show how stable orientations are triggered by the geometric resonance conditions. Analytical predictions are checked using numerical calculations based on the coupled dipoles method (CDA) for the particular case of a chain of silver nanoparticles. The reported resonance driven optical torque allows for a tuning of the orientation of the chain depending on radiation’s wavelength.

Cascaded amplification via three-beam double stimulated Raman scattering in benzene

As stimulated Raman scattering (SRS) microscopy has emerged as a powerful tool for label-free imaging of biomolecules in biological systems, SRS has also received much attention in the field of nonlinear optics. Here, we enhanced the cascade SRS of benzene through an energy competition mechanism in the three-beam double SRS processes. A three-beam (pump, Stokes, and anti-Stokes beam) SRS scheme was formulated and demonstrated to simultaneously induce the parallel and cascaded SRS processes, which were related to the Raman active modes in the same molecule. Both two SRS processes generated high-order Stokes SRS through resonance enhancement of the double sample cell configuration, which effectively suppressed the CARS (Coherent anti-Stokes Raman Scattering) signal. It was shown in the experimental results that the cascaded SRS up to six orders from 562 to 780 nm were generated, and the SRS threshold of the multi-order Stokes components was lowered. The present work can potentially contribute to the development of super-resolution SRS microscopy.

Discovery of conjoined charge density waves in the kagome superconductor CsV3Sb5

The electronic instabilities in CsV3Sb5 are believed to originate from the V 3d-electrons on the kagome plane, however the role of Sb 5p-electrons for 3-dimensional orders is largely unexplored. Here, using resonant tender X-ray scattering and high-pressure X-ray scattering, we report a rare realization of conjoined charge density waves (CDWs) in CsV3Sb5, where a 2 × 2 × 1 CDW in the kagome sublattice and a Sb 5p-electron assisted 2 × 2 × 2 CDW coexist. At ambient pressure, we discover a resonant enhancement on Sb L1-edge (2s→5p) at the 2 × 2 × 2 CDW wavevectors. The resonance, however, is absent at the 2 × 2 × 1 CDW wavevectors. Applying hydrostatic pressure, CDW transition temperatures are separated, where the 2 × 2 × 2 CDW emerges 4 K above the 2 × 2 × 1 CDW at 1 GPa. These observations demonstrate that symmetry-breaking phases in CsV3Sb5 go beyond the minimal framework of kagome electronic bands near van Hove filling.

Design of broadband high efficiency absorption antenna based on metamaterial nano-ring array

Compared with the traditional solar cells, the nano-optical antenna breaks through the band-gap limitation of semiconductor materials, and provides a new scheme for solar energy collection. In order to solve the problems of complex structure, low efficiency and narrow bandwidth of nano-optical antenna, a novel nano-ring-cylinder based on metamaterials is proposed in this paper. The antenna has an average absorption efficiency of 96.93% in the wide-band absorption range of visible and near-infrared light. First of all, the basic design theory of the antenna was given based on the surface plasma theory. Then, the antenna structure design scheme was determined, the overall structure consists of two layers of metal and an insulating layer formed by Al2O3. Finally, on the basis of the established antenna model, the absorption characteristics were analyzed by simulation. The analysis result shows that the super-absorption ability of the antenna is independent of the polarization of the incident light, and the average absorption ability can be maintained at about 91% when the incident angle is ±60°. The absorption capability of the antenna is mainly due to the synergistic effect of Fabry-Perot resonance and localized surface plasmon resonance enhancement. The conclusion can provide a theoretical guidance for the structural design of nano-optical antenna.

Trapezoidal Angled Fiber Coupler for Microsphere Resonator With Enhancement of Fano Resonance

We propose and demonstrate a trapezoidal angled fiber coupler for excitation of whispering-gallery mode microsphere resonator, with enhanced Fano resonance. The reflection from the angled fiber is enhanced when the oblique angle is greater than critical angle, which is obtained as 30° theoretically for angled fiber. To enhance the endface reflection, the front tip of the angled fiber is polished flat to achieve the trapezoidal angled fiber. Compared with angled fiber, the proportion of Fano lineshape in spectra for trapezoidal angled fiber is nearly doubled and the slope is greatly improved, which reaches 304.55 dB/nm. Moreover, through the coupling of dual microspheres, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> factor is improved severalfold and the thermal tuning efficiency is increased by 50%. With the advantage of low cost, easy fabrication procedure and reflection mode operation, the proposed device shows a great potential for sensing, optical tuning and optical switching applications.

Association of late gadolinium enhancement in cardiac magnetic resonance with heart failure outcomes in patients with non-ischemic cardiomyopathy

Abstract Background Late-gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR) has been found to be associated with increased mortality in patients with non-ischemic cardiomyopathy (NICM). The correlation between LGE and heart failure (HF) hospitalization, referral for heart transplant, and ejection fraction (EF) improvement have not been well established. Purpose This meta-analysis assessed the relationship between LGE in CMR with HF hospitalization, referral for heart transplant and EF improvement in patients with NICM. Methods We searched the databases for studies reporting the association between LGE in CMR for NICM and HF outcomes including Ovid MEDLINE, EMBASE, Web of Science, and Google Scholar for all studies. The search was not restricted to time or publication status. The minimal follow up duration is one year. Results A total of 216 studies resulted from the literature search. A total of 25 studies and 3,039 patients (1,265 with LGE vs 1,774 without LGE) were included; mean follow up is around 33 months (ranging between 13 to 71 months). Our analysis demonstrated that LGE in NICM was associated with increased risk of HF hospitalization (odds ratio 3.38, 95% confidence interval 2.27–5.04; P&amp;lt;0.01), referral for transplant (odds ratio 5.08, 95% confidence interval 2.49–10.35; P&amp;lt;0.01), and lower chance for EF improvement (odds ratio 0.16, 95% confidence interval 0.03–0.85; P 0.03). Heterogeneity is moderate: χ2=49.5, df=21 (P=0.001), I2=57%. (Figures 1 and 2) Conclusions Our results suggest that LGE is associated with increased risk of HF hospitalization and referral for heart transplant and lower chance for EF improvement in long-term follow up. Funding Acknowledgement Type of funding sources: None.

Association of late-gadolinium enhancement in cardiac magnetic resonance with ventricular arrhythmias and mortality in patients with non-ischemic cardiomyopathy

Abstract Background Late-gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR) is a predictor of adverse events such as cardiovascular mortality, cardiovascular related hospitalization and defibrillation shocks in patients with non-ischemic cardiomyopathy (NICM). The correlation between LGE and ventricular arrhythmia and mortality has not been completely established. Purpose This meta-analysis assessed the relationship between LGE in CMR with ventricular arrhythmias: sustained, non-sustained and ICD therapy; and mortality in patients with NICM. Methods Databases were queried for studies reporting the association between LGE in CMR in NICM and ventricular arrhythmias and mortality, including Ovid MEDLINE, EMBASE, Web of Science, and Google Scholar. The search was not restricted to time or publication status. The minimal follow up duration was one year. Results A total of 46 studies and 10,548 patients (4,610 with LGE vs 5,938 without LGE) were included; mean follow up was 3 years (ranging between 13 to 71 months) and mean left ventricular ejection fraction 33%. LGE in NICM was associated with increased risk of ventricular arrhythmias and sudden cardiac death (odds ratio 4.595, 95% confidence interval 3.54–5.97; P&amp;lt;0.01) and mortality (odds ratio 2.949, 95% confidence interval 2.285–3.806; P&amp;lt;0.01). Heterogeneity is low to moderate: χ2=82.2, df =45 (P=0.001), I2=45% (Figures 1, 2). Conclusions Our results suggest that LGE is associated with increased risk of ventricular arrhythmias, sudden cardiac death and mortality in long-term follow up. These results further substantiate the need for larger prospective randomized trials using LGE to decide ICD indication regardless of EF. There are two ongoing trials testing this indication: CMR-ICD and CMR-GUIDE. Funding Acknowledgement Type of funding sources: None.

Late gadolinium enhancement is a strong predictor of life threatening arrhythmias in patients with dilated cardiomyopathy undergoing ICD implantation for primary prevention of sudden cardiac death

Abstract Background The usefulness of implantable cardioverter defibrillators (ICD) for primary prevention of arrhythmic sudden cardiac death (SCD) in patients with non-ischemic dilated cardiomyopathy (DCM) has been questioned. Efforts to improve risk stratification have included scores such as the “MADIT-ICD benefit score”, and the use of late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR). The purpose of this study was to evaluate the potential usefulness of these two tools to assess the risk of life-threatening arrhythmias in patients with non-ischemic DCM undergoing ICD implantation for primary prevention of SCD. Methods We conducted a single-center retrospective study of consecutive patients who underwent contrast-enhanced CMR before ICD implantation for primary prevention of SCD. Patients with ischemic cardiomyopathy were used as reference. Patients with non-dilated cardiomyopathies were excluded. The arrhythmic component of the MADIT-ICD benefit score (VT/VF score) was calculated for each patient, and considered high if ≥7, as recommended. The primary endpoint was the occurrence of SCD or life-threatening arrhythmias (VF or VT &amp;gt;200 bpm). Follow-up was performed by device interrogation in all patients except those who suffered SCD. Results A total of 151 patients (93 ischemic, mean age 62±13 years, 75% male) with mean left ventricular ejection fraction (LVEF) of 27±8% were included. Overall, 72% (n=67) ischemic and 45% (n=26) non-ischemic patients had scores ≥7 and were considered high-risk. LGE was present in all patients with ischemic cardiomyopathy, and in 76% (n=44) of patients with non-ischemic DCM. During a median follow-up of 21 (8–38) months, 21 patients (13.9%, 11 ischemic and 10 non-ischemic) met the primary endpoint. Overall, the event-free survival of non-ischemic patients was similar to that of ischemic patients (log rank p=0.269). In patients with non-ischemic DCM, there were 7 arrhythmic events (26.9%) in those with MADIT-ICD VT/VF scores ≥7, and 3 events (9.4%) in those with scores &amp;lt;7 (log rank p=0.104). In the same population, there were 10 arrhythmic events (23%) in patients with LGE, but no events in patients without LGE (log rank p=0.036). LVEF was similar in patients with and without arrhythmic events (26±8% vs. 27±7%, p=0.717), and in those with and without LGE (26±7% vs. 28±9%, p=0.342). Conclusion The presence of LGE is a strong predictor of life threatening arrhythmias in patients in non-ischemic DCM undergoing ICD implantation for primary prevention, seemingly outperforming the clinical MADIT-ICD benefit score. Funding Acknowledgement Type of funding sources: None.

Multimodality imaging predictors of appropriate ICD shock and mortality in adults with cardiac sarcoidosis

Abstract Background Identifying patients with cardiac sarcoidosis (CS) who are at increased risk of sudden cardiac death (SCD) is imperative. Current guideline recommendations for implantable cardioverter-defibrillator (ICD) implantation in patients with CS are based on small observational studies and have not been validated in contemporary cohorts using multimodality cardiac imaging. Purpose The aim of this study was to characterize a cohort of patients with tissue-proven cardiac sarcoidosis who underwent multimodality cardiac imaging and identify predictors of appropriate ICD shock and mortality. Methods We retrospectively identified subjects with a diagnosis of CS established by clinical/imaging criteria, and tissue biopsy (N=273) seen at our tertiary care center between 2001 and 2021. Clinical characteristics and outcomes were collected from electronic medical records. The primary endpoint of interest was a composite of appropriate ICD shock and all-cause mortality. Secondary endpoints were individual rates of appropriate ICD shock and all-cause mortality. Cox proportional hazard regression analysis was used to identify independent predictors of the outcomes. Results Mean age was 59±11 years and 40% were female. Isolated CS was found in 49 subjects (17.9%). The prevalence of traditional cardiovascular risk factors was low. Atrial fibrillation prevalence was high (41%). After a median follow-up of 7.9 years, the rate of appropriate ICD shock and all-cause mortality was 29% (N=79). The 5-year overall survival rate of 97.5%. Age, left ventricular ejection fraction (LVEF), and delayed gadolinium enhancement (DGE) in cardiac magnetic resonance (CMR) were independent predictors of the primary composite endpoint; LVEF and DGE in CMR were independent predictors of appropriate ICD-shock; and LVEF and baseline serum NT proBNP were independent predictors of overall mortality. An LVEF of 47% was identified as the optimal cutoff in predicting the primary composite endpoint. Presence of scar, inflammation or mismatch pattern in positron emission tomography were not significant predictors of the outcomes. Conclusion In this large cohort of subjects with CS, we found that the presence of DGE in CMR was the strongest independent predictor of the composite endpoint of appropriate ICD-shock and mortality and of appropriate ICD-shock individually; LVEF by echocardiogram was an independent predictor of the primary and secondary endpoints with an optimal LVEF cutoff for predicting the composite endpoint of 47%. Funding Acknowledgement Type of funding sources: None.

Broadband directional resonant tunneling emission enhancement via acoustic anisotropic metamaterials

Broadband directional acoustic emission enhancement is essential in practical applications, such as acoustic communication and medical imaging. In this paper, an anisotropic metamaterial array of meta-unit consisting of a straight channel and four symmetrical side branch cavities is proposed, aiming to achieve broadband directional resonant tunneling acoustic emission enhancement via the coupling of the transmission peaks in the y-direction. In the range of 3335–4625 Hz, the broadband anisotropic characteristic is reflected in the opposite transmission capacities of the meta-unit and periodic array in the orthogonal directions, which is caused by the different effective impedances due to resonant tunneling. Numerical simulation shows that for the anisotropic metamaterial array with a monopole source in the center, the broadband directional acoustic emission enhancement phenomenon appears in the y-direction. The experimental results confirm that at a distance of 35 cm from the point source, the SPL gain in the y-direction is 4 dB on average, and the SPL in the x-direction is reduced by an average of 12 dB. Based on the above results, the proposed anisotropic metamaterial array is expected to show significant potential applications in the fields where broadband acoustic signals are required.

Plasmon-Induced Semiconductor-Based Photo-Thermal Catalysis: Fundamentals, Critical Aspects, Design, and Applications

Photo-thermal catalysis is among the most effective alternative pathways used to perform chemical reactions under solar irradiation. The synergistic contributions of heat and light during photo-thermal catalytic processes can effectively improve reaction efficiency and alter design selectivity, even under operational instability. The present review focuses on the recent advances in photo-thermal-driven chemical reactions, basic physics behind the localized surface plasmon resonance (LSPR) formation and enhancement, pathways of charge carrier generation and transfer between plasmonic nanostructures and photo-thermal conversion, critical aspects influencing photo-thermal catalytic performance, tailored symmetry, and morphology engineering used to design efficient photo-thermal catalytic systems. By highlighting the multifield coupling benefits of plasmonic nanomaterials and semiconductor oxides, we summarized and discussed several recently developed photo-thermal catalysts and their catalytic performance in energy production (CO2 conversion and H2 dissociation), environmental protection (VOCs and dyes degradation), and organic compound synthesis (Olefins). Finally, the difficulties and future endeavors related to the design and engineering of photo-thermal catalysts were pointed out to draw the attention of researchers to this sustainable technology used for maximum solar energy utilization.

Dynamic electrocatalysis: Examining resonant catalytic rate enhancement under oscillating electrochemical potential

A microkinetic analysis is presented for a generalized electrocatalytic reaction mechanism to evaluate whether oscillating electrochemical potential can be used to achieve resonant catalytic rate enhancement. It is illustrated that because changing the potential changes the free energy of reaction, this approach is conceptually distinct from oscillating binding energies of catalytic intermediates as within catalytic resonance theory. For faradaic reactions in series, no enhancements relative to the maximum steady-state turnover rate (within the potential range spanned by oscillation) are achievable, even in cases where the potential limits favor adsorption and desorption, respectively. It is possible to exceed a time-averaged steady-state rate (weighted by time at each condition), although only if the elementary reactions show disparate responses to potential. In contrast, if a faradaically driven parallel reaction controls surface coverage of a strongly adsorbed blocking species, significant dynamic enhancements over the maximum steady-state can be achieved, albeit at a cost of thermodynamic efficiency. • Electrocatalytic reactions are evaluated under conditions of oscillating potential • Pure series reactions cannot exceed the steady-state rate at the highest potential • Parallel reactions can allow dynamic enhancement, but energy efficiency is sacrificed Recent simulations have shown that heterogeneous catalysts with dynamic properties—for example, the ability to vary adsorbate binding energy with time—could, in principle, give higher rates than an optimized catalyst operating at steady state (i.e., the Sabatier principle or “volcano curve” maximum, assuming typical correlations shaping the energy landscape of the reaction). Enhancements may be realized by oscillating catalyst properties at frequencies near the timescales of the elementary steps. Variation of electrochemical potential has been proposed as a possible method to induce such rate enhancements in electrocatalytic systems, but the extent to which this method could be effective has not been fully explored. Deeper understanding of electrochemical systems is also broadly critical, as electrocatalysis is well suited to utilize energy from renewables such as wind and solar power for the production of fuels, chemicals, and materials with low carbon intensity. Certain electrocatalytic reactions can be accelerated by varying the applied potential with time. Requirements for this promotional effect are identified and contrasted with other approaches attempting to create catalysts that accelerate reaction rates with dynamically tunable surface properties.

Toward interferometry of neutrino electromagnetism

It is predicted within the Standard Model of elementary particles that asymmetric neutrino environments cause rotation of linear polarization of electromagnetic wave -- the birefringence. We demonstrate that this effect is strongly enhanced if additionally the photon is propagating through refractive medium, which effectively increases the photon exposure to the neutrino medium. Our estimate for infrared laser beam in $1\,\mathrm{m}$ long optical fiber exposed to reactor anti-neutrino flux results in linear polarization rotation by the angle $\sim4.6\times10^{-39}\,\mathrm{rad}$. We also derive the proper dependence of the effect on the angle between the directions of photon and neutrino propagation in the laboratory frame. For that purpose we derive the correct form of the basis of polarization four-vectors, which differs from the one widely used in literature. We also estimate the sub-leading optical effect of the neutrino medium due to the neutrino dipole magnetic moment, in terms of a variation of the refractive index and its angular dependence. A rough monochromatic approximation points towards the existence of a resonant enhancement of the effect.

Resonant enhancement of particle emission from a parametrically driven condensate in a one-dimensional lattice

Motivated by recent experiments, we investigate particle emission from a Bose-Einstein condensate in a one-dimensional lattice, where the interaction strength is periodically modulated. The modulated interactions parametrically excite a collective mode, leading to density oscillations. These collective oscillations in turn drive particle emission. This multistep process amplifies the drive, producing larger particle jets. We find that the amplitude dependence of the emission rate has a characteristic threshold behavior, as seen in experiments.