Storage and Retrieval of Thermal Light in Warm Atomic Vapor

We report slowed propagation and storage and retrieval of thermal light in warm rubidium vapor using the effect of electromagnetically-induced transparency (EIT). We first demonstrate slowed-propagation of the probe thermal light beam through an EIT medium by measuring the second-order correlation function of the light field using the Hanbury-Brown$-$Twiss interferometer. We also report an experimental study on the effect of the EIT slow-light medium on the temporal coherence of thermal light. Finally, we demonstrate the storage and retrieval of thermal light beam in the EIT medium. The direct measurement of the photon number statistics of the retrieved light field shows that the photon number statistics is preserved during the storage and retrieval process.Comment: 4 pages, 4 figure

Reversing the Weak Quantum Measurement for a Photonic Qubit

We demonstrate the conditional reversal of a weak (partial-collapse) quantum measurement on a photonic qubit. The weak quantum measurement causes a nonunitary transformation of a qubit which is subsequently reversed to the original state after a successful reversing operation. Both the weak measurement and the reversal operation are implemented linear optically. The state recovery fidelity, determined by quantum process tomography, is shown to be over 94% for partial-collapse strength up to 0.9. We also experimentally study information gain due to the weak measurement and discuss the role of the reversing operation as an information erasure

AN ATOMIC LAYER DEPOSITION PASSIVATED SURFACE ACOUSTIC WAVE SENSOR FOR BACTERIAL BIOFILM GROWTH MONITORING

This thesis reports for the first time the design, fabrication, and testing of a reusable Surface Acoustic Wave (SAW) sensor for biofilm growth monitoring. Bacterial biofilms cause severe infections, and are often difficult to remove without an invasive surgery. Thus, their detection at an early stage is critical for effective treatments. A highly sensitive SAW sensor for biofilm growth monitoring was fabricated by depositing a high quality zinc oxide (ZnO) piezoelectric thin film by pulsed laser deposition (PLD). The sensor was successfully passivated by aluminum oxide (Al2O3) using Atomic Layer Deposition (ALD) to prevent ZnO damage from long term media contact. The sensor was reusable over multiple biofilm formation experiments using the ALD Al2O3 passivation and an oxygen plasma biofilm cleaning method. The SAW sensor was studied with Escherichia coli biofilm growth in Lysogeny Broth (LB) and in 10% Fetal Bovine Serum (FBS) as a simulated an in vivo environment. A multiple MHz level resonant frequency shift measured at the output of the SAW sensor in both LB and 10% FBS corresponded to the natural biofilm growth progression. These repeatable E. coli biofilm growth monitoring results validate the novel application of a SAW sensor for future implantable biofilm sensing applications

Early-type Host Galaxies of Type Ia Supernovae. I. Evidence for Downsizing

Type Ia supernova (SN Ia) cosmology provides the most direct evidence for the presence of dark energy. This result is based on the assumption that the look-back time evolution of SN Ia luminosity, after light-curve corrections, would be negligible. Recent studies show, however, that the Hubble residual (HR) of SN Ia is correlated with the mass and morphology of host galaxies, implying the possible dependence of SN Ia luminosity on host galaxy properties. In order to investigate this more directly, we have initiated spectroscopic survey for the early-type host galaxies, for which population age and metallicity can be more reliably determined from the absorption lines. As the first paper of the series, here we present the results from high signal-to-noise ratio (>100 per pixel) spectra for 27 nearby host galaxies in the southern hemisphere. For the first time in host galaxy studies, we find a significant (~3.9sigma) correlation between host galaxy mass (velocity dispersion) and population age, which is consistent with the "downsizing" trend among non-host early-type galaxies. This result is rather insensitive to the choice of population synthesis models. Since we find no correlation with metallicity, our result suggests that stellar population age is mainly responsible for the relation between host mass and HR. If confirmed, this would imply that the luminosity evolution plays a major role in the systematic uncertainties of SN Ia cosmology.Comment: Accepted for publication in ApJ

Private transfers and emerging welfare states in East Asia: Comparative perspectives

Empirical studies on income distribution and poverty have indicated that the public transfer system has been successful in terms of poverty and inequality reduction in welfare states. However, very little attention has been paid to private transfers in this analysis. Recently, while there has been an increasing interest in the unique features of East Asian welfare states/regimes, many scholars have begun to have an interest in the role of the family in their welfare mix. This article aims to widen the scope of comparative income studies, firstly by analyzing 12 Western welfare states and two newly emerging East Asian welfare states, i.e. South Korea and Taiwan, and secondly, by comparing the poverty and inequality reduction effects of private transfers with those of public transfers. The Luxemburg Income Study dataset is used for the analysis. The empirical results indicate that private transfers are much more effective than public transfers in terms of income inequality and poverty reduction effects in both South Korea and Taiwan, in contrast to western counterparts including three Southern European countries. Finally, based on the results, we propose further research questions

Feminisation of poverty in 12 welfare states: Strengthening cross-regime variations?

The feminisation of poverty is said to have become a common feature in the majority of advanced welfare states, but it is equally true that there has been significant variation in the feminisation of poverty from one country to another. While the concept of the feminisation of poverty remains controversial, there have been very few attempts to reveal a detailed picture from a comparative perspective. Considering this background, this study aims to illustrate the feminisation of poverty in 12 welfare states (Liberal - Australia, Canada, UK, US; Conservative - Austria, France, Germany, Italy; Nordic - Denmark, Finland, Norway, Sweden) between the 1980s and the 2000s and to analyse whether or not there has been any convergence or divergence between these welfare states. This study will evaluate the scope and depth of the feminisation of poverty by conducting analyses not only in terms of different sex, but in terms of different population groups. Further, the changing role of welfare states will be assessed via an analysis of the antipoverty role of public transfers in each country. The Luxemburg Income Study dataset will be used for empirical analysis. This paper will argue that while the feminisation of poverty has been slowed down and even reversed in certain cases, cross-national differences have been increasingly visible. The results of this study also show that the welfare regime framework can prove to be a useful tool for understanding the similarities and the differences in the feminisation of poverty across different Western welfare state regimes