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