802 research outputs found
Ultra-high neutrino fluxes as a probe for non-standard physics
We examine how light neutrinos coming from distant active galactic nuclei
(AGN) and similar high energy sources may be used as tools to probe
non-standard physics. In particular we discuss how studying the energy spectra
of each neutrino flavour coming from such distant sources and their distortion
relative to each other may serve as pointers to exotic physics such as neutrino
decay, Lorentz symmetry violation, pseudo-Dirac effects, CP and CPT violation
and quantum decoherence. This allows us to probe hitherto unexplored ranges of
parameters for the above cases, for example lifetimes in the range s/eV for the case of neutrino decay. We show that standard
neutrino oscillations ensure that the different flavours arrive at the earth
with similar shapes even if their flavour spectra at source may differ strongly
in both shape and magnitude. As a result, observed differences between the
spectra of various flavours at the detector would be signatures of non-standard
physics altering neutrino fluxes during propagation rather than those arising
during their production at source. Since detection of ultra-high energy (UHE)
neutrinos is perhaps imminent, it is possible that such differences in spectral
shapes will be tested in neutrino detectors in the near future. To that end,
using the IceCube detector as an example, we show how our results translate to
observable shower and muon-track event rates.Comment: 16 pages, 10 figure
Quantum metrology with nonclassical states of atomic ensembles
Quantum technologies exploit entanglement to revolutionize computing,
measurements, and communications. This has stimulated the research in different
areas of physics to engineer and manipulate fragile many-particle entangled
states. Progress has been particularly rapid for atoms. Thanks to the large and
tunable nonlinearities and the well developed techniques for trapping,
controlling and counting, many groundbreaking experiments have demonstrated the
generation of entangled states of trapped ions, cold and ultracold gases of
neutral atoms. Moreover, atoms can couple strongly to external forces and light
fields, which makes them ideal for ultra-precise sensing and time keeping. All
these factors call for generating non-classical atomic states designed for
phase estimation in atomic clocks and atom interferometers, exploiting
many-body entanglement to increase the sensitivity of precision measurements.
The goal of this article is to review and illustrate the theory and the
experiments with atomic ensembles that have demonstrated many-particle
entanglement and quantum-enhanced metrology.Comment: 76 pages, 40 figures, 1 table, 603 references. Some figures bitmapped
at 300 dpi to reduce file siz
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This dissertation discusses the usage of the hybrid entanglement between two different qubit encodings to achieve both the high teleportation success probability and the high fidelity between the input and target qubit. For the high success probability, I utilize the many-photon qubit encoding such as the coherent-state qubit with large amplitude and multiphoton qubit of polarized photons since these encodings have the nearly-deterministic Bell-state measurement schemes. The small-photon qubit encoding, in contrast, shows the better behavior on the photon loss. This encoding includes a vacuum-and-single-photon (VSP) qubit, polarized single-photon (PSP) qubit, and coherent-state qubit with a small amplitude. I consider the hybrid entanglement for a coherent-state qubit to a VSP qubit and a multiphoton qubit to all small-photon qubits.
First, the analysis of the hybrid entanglement of a coherent-state qubit shows that the success probability withstands more photon losses as the amplitude of coherent-state qubit increases. The fidelity is affected by the losses both on the coherent-state qubit and VSP qubit, but the loss of the coherent-state qubit affects it more severely especially for large amplitude.
Second, the hybrid entanglement of a multiphoton qubit shows that the fidelity is determined by the loss of the small-photon qubit side while the success probability depends on loss only in the multiphoton qubit side. Especially, the hybrid entanglement with the VSP qubit tolerates 10 times more photon-loss rate than the direct transmission in high fidelity regime (F>90%). For the success probability, I propose the optimal photon number consisting of a multiphoton qubit. The generation methods for the required entangled states are additionally discussed.
I further investigate the quantum resources of light other than entanglement: coherence and nonclassicality. I propose physically motivated coherence measures from the role of coherence in the quantum Fisher information and expectation values of quantum observables. For the latter measure, the semidefinite programming provides an efficient method to compute the involved optimization. The suggested nonclassicality measure is based on the negativity of the Glauber-Sudarshan P function. The singular behavior of the P function is dealt with by the filtering on the Fourier space. The negativity is proven to be equivalent to the robustness of mixing with the classical state, which gives its operational meaning.κ΄ν μμ€ν
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νμ¬, μ‘°μμ μΈ κ΄μ μμ μλ―Έ λν μ μνλ€.Abstract i
I. Introduction 1
II. Hybrid entanglement of light and teleportation of many-photon
qubit encodings 5
2.1 Introduction 5
2.2 Photon-loss model 7
2.3 Teleportation using the hybrid entanglement between a VSP qubit and a coherent-state qubit 8
2.3.1 Loss on hybrid entanglement 8
2.3.2 Output state of the teleportation 9
2.3.3 Fidelity 12
2.3.4 Success probability 13
2.4 Teleportation of a multi-photon qubit using a carrier qubit 15
2.4.1 Review of multiphoton qubit 15
2.4.2 Loss on hybrid entangled states 17
2.4.3 Output states and their fidelities 22
2.4.4 Success probabilities 31
2.5 Generation of hybrid entangled states 34
2.6 Remarks 38
III. Operational quantum resources beyond entanglement 43
3.1 Introduction 43
3.2 Measuring coherence via observable quantum effects 45
3.2.1 Preliminaries 45
3.2.2 Coherence and Quantum Fisher Information 47
3.2.3 Coherence measures from quantum observables 54
3.2.4 Examples 63
3.3 Measuring Nonclassicality via negativity 65
3.3.1 Nonclassicality filtering 65
3.3.2 Negativity as a linear optical monotone 70
3.3.3 Operational interpretations of the negativity 72
3.3.4 Approximate nonclassicality monotones 75
3.3.5 Examples 79
3.4 Remarks 81
IV. Conclusion 85
Bibliography 89
Abstract in Korean 103Docto
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Inferring structures, free energy differences, and kinetic rates of biological macromolecular assemblies by integrative modeling
Biological macromolecular assemblies play crucial roles in most cellular processes. The determination of their structures, thermodynamics, and kinetics is essential to understand their function, evolution, modulation, and design. Determining such models, however, remains challenging. One particularly powerful approach to constructing models in general is integrative modeling. Integrative modeling aims to maximize the accuracy, precision, and completeness of models, by simultaneously utilizing all available information, including experimental data, physical principles, statistical analyses, and other prior models. The goal of this thesis is to expand the scope of integrative modeling to the inference of spatial, thermodynamic, and kinetic aspects of macromolecular assemblies. In Chapter I, I introduce the integrative modeling framework for spatiotemporal modeling of biological macromolecular assemblies. In Chapter II, I demonstrate how the synergy between multi-chemistry cross-linking mass spectrometry and integrative modeling can map the structural dynamics of macromolecular assemblies, by application to the human Cop9 signalosome complex. In Chapter III, I present a method for determining structures, free energy differences, and kinetic rates of macromolecular assemblies along their functional cycle, mainly from negative stain electron microscopy (EM). We apply the method to the yeast Hsp90 to estimate the free energy differences and kinetic parameters along its nucleotide hydrolysis cycle, which includes open and closed states of Hsp90. In Chapter IV, I describe a validation of stochastic sampling in integrative modeling. The remaining chapters describe applications of integrative modeling to assemblies of various sizes and scales, using various sources of information, thus illustrating the flexibility of the integrative modeling approach. Specifically, I apply integrative modeling to the human ECM29-Proteasome assembly under oxidative stress (Chapter V), the yeast nuclear pore complex (NPC) cytoplasmic mRNA export platform (Chapter VI), the major membrane ring component of the yeast NPC (Chapter VII), the entire yeast NPC (Chapter VIII), and the reconstruction of 3D structures of MET antibodies (Chapter IX)
The Dynamics of Energy Systems and the Logistic Substitution Model
This work is dedicated to the empirical testing and theoretical formulation of an invariant, the logistic learning curve, as it applies to the structural evolution of energy systems and systems related to energy, such as coal mining. The great success of the model in organizing past data, and the insensitivity to major political and economic perturbations of the structures obtained seem to lend great predictive power to this invariant
Quantum information with Gaussian states
Quantum optical Gaussian states are a type of important robust quantum states
which are manipulatable by the existing technologies. So far, most of the
important quantum information experiments are done with such states, including
bright Gaussian light and weak Gaussian light. Extending the existing results
of quantum information with discrete quantum states to the case of continuous
variable quantum states is an interesting theoretical job. The quantum Gaussian
states play a central role in such a case. We review the properties and
applications of Gaussian states in quantum information with emphasis on the
fundamental concepts, the calculation techniques and the effects of
imperfections of the real-life experimental setups.
Topics here include the elementary properties of Gaussian states and relevant
quantum information device, entanglement-based quantum tasks such as quantum
teleportation, quantum cryptography with weak and strong Gaussian states and
the quantum channel capacity, mathematical theory of quantum entanglement and
state estimation for Gaussian states.Comment: 170 pages. Minors of the published version are corrected and listed
in the Acknowledgement part of this versio
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