462 research outputs found
Theoretical investigation of photon manipulation for quantum computing and quantum information processing
Quantum computing and quantum information processing are fast developing fields. As more and more qubits are integrated into the quantum computing systems, a deeper understanding and more careful modeling of the dynamics of these quantum systems in presence of driving and/or loss are necessary, not only for optimizing existing quantum devices, but also for designing and achieving novel method for more precise manipulation of these quantum systems. Our work investigating these quantum systems is inspired by quantum optics, a field focused on the quantum description of light and light-matter interactions.
In this thesis, we use the theoretical toolboxes provided by quantum optics as well as condensed matter theory to investigate and model realistic quantum systems. Specifically, we focus on the Nitrogen-vacancy centers in diamond crystal, a Josephson parametric amplifier (that uses Josephson junctions as its non-linear elements), and plasmonic nanowire system. With the knowledge of the dynamics of these systems, we proposed single-photon heralded two-NV center quantum gates; designed and optimized the superconducting circuit for a Josephson parametric amplifier to improve the amplifier's saturation power; and designed new methods for robust light manipulation using topologically protected plasmonic modes. All the devices that we study are either ready to be implemented in experiments or have already been built. Further, as discussed in this thesis, our theoretical analysis of NV-centers can be extended to similar device types like solid-state defect centers, while our analysis of Josephson parametric amplifiers can be extended to other types of superconducting circuit systems
Spectral Properties of Galaxies in Void Regions
We present a study of spectral properties of galaxies in underdense
large-scale structures, voids. Our void galaxy sample (75,939 galaxies) is
selected from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) with
. We find that there are no significant differences in the
luminosities, stellar masses, stellar populations, and specific star formation
rates between void galaxies of specific spectral types and their wall
counterparts. However, the fraction of star-forming galaxies in voids is
significantly higher () than that in walls. Void galaxies, when
considering all spectral types, are slightly fainter, less massive, have
younger stellar populations and of higher specific star formation rates than
wall galaxies. These minor differences are totally caused by the higher
fraction of star-forming galaxies in voids. We confirm that AGNs exist in
voids, already found by \cite{co08}, with similar abundance as in walls. Type I
AGNs contribute 1\%-2\% of void galaxies, similar to their fraction in
walls. The intrinsic [O III] luminosities , spanning over 10^6\ L_{\sun} \sim
10^9\ L_{\sun}, and Eddington ratios are similar comparing our void AGNs
versus wall AGNs. Small scale statistics show that all spectral types of void
galaxies are less clustered than their counterparts in walls. Major merger may
not be the dominant trigger of black hole accretion in the luminosity range we
probe. Our study implies that the growth of black holes relies weakly on large
scale structures.Comment: 14 pages,16 figures, accepted for publication in Ap
Zinc-Chelating Mechanism of Sea Cucumber (Stichopus japonicus)-Derived Synthetic Peptides
In this study, three synthetic zinc-chelating peptides (ZCPs) derived from sea cucumber hydrolysates with limited or none of the common metal-chelating amino-acid residues were analyzed by flame atomic absorption spectroscopy, circular dichroism spectroscopy, size exclusion chromatography, zeta-potential, Fourier transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy. The amount of zinc bound to the ZCPs reached maximum values with ZCP:zinc at 1:1, and it was not further increased by additional zinc presence. The secondary structures of ZCPs were slightly altered, whereas no formation of multimers was observed. Furthermore, zinc increased the zeta-potential value by neutralizing the negatively charged residues. Only free carboxyl in C-terminus of ZCPs was identified as the primary binding site of zinc. These results provide the theoretical foundation to understand the mechanism of zinc chelation by peptides
Antioxidant and anti-dyslipidemic effects of polysaccharidic extract from sea cucumber processing liquor
Sea cucumber is a seafood of high nutritional value. During its processing, sea cucumber processing liquor is routinely produced, which is usually discarded as waste. The chemical composition of this processing liquor is similar to sea cucumbers themselves. Hence, valuable ingredients, such as functional polysaccharides, could be obtained from them. Results Biologically active polysaccharides from sea cucumber processing liquor were extracted through protease hydrolysis and electroosmosis. The analysis revealed that the polysaccharide extract from sea cucumber processing liquor (PESCPL) is predominantly composed of mannose, in addition to some glucose and fucose. The antioxidant activity of PESCPL was analyzed using in vitro. It was demonstrated that PESCPL could effectively scavenge 1,1-diphenyl-2-picrylhydrazyl radicals, hydroxyl radicals, and superoxide anion radicals. The effect of PESCPL was investigated in vivo by using mice model fed with high-fat diets with/without PESCPL supplement. It was shown that PESCPL could increase the catalase and superoxide dismutase activity in the serum and decrease serum malonaldehyde content. Furthermore, mice fed with PESCPL diet showed a considerable decrease in the serum cholesterol and triglyceride levels and an increase in high-density lipoprotein cholesterol levels. Conclusions Our research highlights that PESCPL is a natural antioxidant and could be utilized as a therapeutic supplement for dyslipidemia
Molecular simulations of sliding on SDS surfactant films
We use molecular dynamics simulations to study the frictional response of the
anionic surfactant sodium dodecyl sulfate (SDS) monolayers and hemicylindrical
aggregates physisorbed on gold. Our simulations of a sliding spherical asperity
reveals two friction regimes: At low loads, the films show Amontons' friction
with a friction force that rises linearly with normal load. At high loads, the
friction force is independent of load as long as no direct solid-solid contact
occurs. The transition between these two regimes happens when only a single
molecular layer is confined in the gap between the sliding bodies. The friction
force at high loads on a monolayer rises monotonically with film density and
drops slightly with the transition to hemicylindrical aggregates. This
monotonous increase of friction force is compatible with a traditional plowing
model of sliding friction. At low loads, the friction coefficient reaches a
minimum at intermediate surface concentrations. We attribute this behavior to a
competition between adhesive forces, repulsion of the compressed film, and the
onset of plowing.Comment: 14 pages, 10 figure
Protocol for nearly deterministic parity projection on two photonic qubits
Photonic parity projection plays a significant role in photonic quantum
information processing. Non-destructive parity projections normally require
high-fidelity Controlled-Z gates between photonic and matter qubits, which can
be experimentally demanding. In this paper, we propose a nearly deterministic
parity projection protocol on two photonic qubits which only requires stable
matter-photon Controlled-Phase gates. The fact that our protocol does not
require perfect Controlled-Z gates makes it more amenable to experimental
implementation.Comment: 12+6 pages, 11 figure
Quantum Memory: A Missing Piece in Quantum Computing Units
Memory is an indispensable component in classical computing systems. While
the development of quantum computing is still in its early stages, current
quantum processing units mainly function as quantum registers. Consequently,
the actual role of quantum memory in future advanced quantum computing
architectures remains unclear. With the rapid scaling of qubits, it is
opportune to explore the potential and feasibility of quantum memory across
different substrate device technologies and application scenarios. In this
paper, we provide a full design stack view of quantum memory. We start from the
elementary component of a quantum memory device, quantum memory cells. We
provide an abstraction to a quantum memory cell and define metrics to measure
the performance of physical platforms. Combined with addressing functionality,
we then review two types of quantum memory devices: random access quantum
memory (RAQM) and quantum random access memory (QRAM). Building on top of these
devices, quantum memory units in the computing architecture, including building
a quantum memory unit, quantum cache, quantum buffer, and using QRAM for the
quantum input-output module, are discussed. We further propose the programming
model for the quantum memory units and discuss their possible applications. By
presenting this work, we aim to attract more researchers from both the Quantum
Information Science (QIS) and classical memory communities to enter this
emerging and exciting area.Comment: 41 pages, 11 figures, 7 table
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