Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"quantum channel"”.
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Detection and estimation of quantum channel capacities
This thesis investigates the subject of quantum channel capacities and is composed of two parts. 1. Detecting positive quantum capacities of quantum channels Determining whether a noisy quantum channel can be used to reliably transmit qubits at a non-zero rate is a challenging problem, since it …
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Discrimination of Quantum Channels
… and error rates for the task of binary quantum channel discrimination, where the main focus lies on proving optimal asymmetric error exponents (both asymptotically and non-asymptotically) for different variants of this problem. The task of binary quantum channel discrimination is to …
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Soft Processing Techniques for Quantum Key Distribution Applications
… information reconciliation and data sifting for Quantum Key Distribution (QKD). A novel composite channel model for QKD is identified, which includes both a hard output quantum channel and a soft output classic channel. The Log-Likelihood Ratios, - also called soft-metrics - derived from the two …
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Information-theoretic aspects of quantum channels
Quantum information theory is an important element of quantum computing and quantum communication systems. Whenever a quantum computer needs to send an output state to another party, or two parties need to establish quantum entanglement or secure keys via quantum communication, a quantum channel is …
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Distillation and simulation in quantum information
… tasks, i.e., distillation and simulation in quantum information theory. We investigate these tasks in a unified framework of resource theory and focus on their computation and characterization with finite resources. Particularly we study the tradeoff among relevant parameters such as the …
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Experimental Demonstration of Lindblad Tomography on a Superconducting Quantum Device
Information loss in experimental quantum devices is traditionally characterized using metrics such as T₁ and T₂, which are readily accessible from standard time-domain measurement. While T₁ and T₂ times provide rough heuristics for interaction between single qubits and their lossy environments, …
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RECOVERY AND RECONSTRUCTION IN QUANTUM SYSTEMS
Quantum systems are prone to noises. Accordingly, many techniques are developed tocancel the action of a quantum operation, or to protect the quantum information against the noises. In this dissertation, I discuss two such schemes, namely the recovery channel and the quantum error correction, and …
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Information theoretic parameters for graphs and operator systems
… of matrices appropriate for applications in quantum information, and discuss the concept of entropy over a convex corner. We recall the definition of a non-commutative graph from the work of Duan, Severini and Winter, and with a given non-commutative graph we associate a number of convex …
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Investigation of machine learning techniques in stabilization of co-propagating polarization encoded photons
Quantum communication protocols and networks have advanced considerably in experimental laboratories; however, their operation is frequently constrained by short time frames and significant environmental noise. These challenges affect both time-coded and polarization-encoded photon systems. …
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Using hyperentanglement for advanced quantum communication
"The field of quantum information science promises incredible enhancements in computing, metrology, simulation, and communication, but the challenge of creating, manipulating, and measuring the large quantum states has limited current implementations of such techniques. Such limitations affect …
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Entropic Continuity Bounds & Eventually Entanglement-Breaking Channels
… is given by the repeated application of a quantum channel. In the first part of the thesis, we present a general technique for establishing local and uniform continuity bounds for Schur concave functions; that is, for real-valued functions which are decreasing in the majorization pre-order. …
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Control, gates, and error suppression with Hamiltonians in quantum computation
… perform simulation, and implement logic gates in quantum computation within the context of using Hamiltonian controls. We also study the complexity class QMA-complete. We first investigate a method (introduced by Jordan, Farhi, and Shor) for suppressing environmentally induced errors in …
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Network Integration of a Quantum Dot Entangled Photon-pair Source
… photon-pair sources based on semiconductor quantum dots are promising devices for the construction of a secure quantum network, thanks to their natural lack of multi photon-pair generation. In the previous decades, we have witnessed the achievements on a large variety of quantum dot light …
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Extracting classical information from quantum states : fundamental limits, adaptive and finite-length measurements
… and efficient optical communication systems, quantum mechanics of information processing has become the key element in determining the fundamental limits of physical channels, and in designing quantum communication systems that approach those fundamental limits. To achieve higher data rates …
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Robustness of Fixed Points of Quantum Processes
… of fixed points (or invariant states) of quantum processes. In the first part of the thesis, we address the following question: Given a quantum channel and a quantum state which is almost a fixed point of the channel, can we find a new channel and a new state, which are respectively close …
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Lossless quantum data compression and secure direct communication
Diese Dissertation behandelt die Kodierung und Verschickung von Information durch einen Quantenkanal. Ein Quantenkanal besteht aus einem quantenmechanischen System, welches vom Sender manipuliert und vom Empfänger ausgelesen werden kann. Dabei repräsentiert der individuelle Zustand des Kanals die …
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Stochastic Models of Surface Limited Electronic and Heat Transport in Metal and Semiconductor Contacts, Wires, and Sheets — Micro to Nano
… in the eld of thermoelectric devices. For rough channels of width below 10 nm, electronic transport is additionally modeled using a novel non-parabolic 3D recursive Green function scheme, leading to an estimation of reduced electronic transmission in rough semiconductor wires based on the quantum …