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.
Results
Showing 1 to 20 of 47 for “"coherence time"”.
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Developing the spin qubit of the tin-vacancy center in diamond for quantum networks
… properties of the SnV spin qubit such as its lifetime and coherence time, (2) the first demonstration of quantum control over the SnV spin qubit, and (3) the utilization of quantum control to prolong the SnV spin qubit coherence time by three orders of magnitude at a readily attainable temperature …
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Electronic Energy Transfer in Conjugated Organic Dendrimers and Polymers
… dendrimers are elucidated via steady-state and time-resolved spectroscopy on specially synthesized PA dendrons, and comparison with ab initio calculations. The results are explained by using a variable coupling exciton model. Coherence effects in a model two-level system with trap are examined …
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Optical Control over Nuclear Spins
… A qubit system that simultaneously has long coherence time, fast operation, and large scalability is highly desirable. Particularly, nuclear spins have been considered as ideal quantum information carriers thanks to their exceptionally long coherence time exceeding minutes and even hours at …
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Nuclear spin coherence times of HD trapped in solid parahydrogen matrices
… systematic measurements of nuclear spin coherence and relaxation across controlled impurity conditions remain limited. This dissertation describes the design, construction, and operation of an apparatus that addresses the need to improve existing coherence-time measurements. In this …
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Architectures for photon-mediated quantum information processing
… and experimentally demonstrated values of coherence time and photonic coupling efficiency. In the quantum network architecture, the only operation at every node is probabilistic Bell measurement.
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Impact of Channel Estimation Errors on Space Time Trellis Codes
Space Time Trellis Coding (STTC) is a unique technique that combines the use of multiple transmit antennas with channel coding. This scheme provides capacity benefits in fading channels, and helps in improving the data rate and reliability of wireless communication. STTC schemes have been primarily …
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Pulse Design for Two-Qubit Gates in Superconducting Circuits
… to the highest attainable levels given limited coherence time, it is essential to develop a systematic framework to optimize protocols for implementing two-qubit gates. In this thesis, we formulate the design of the control trajectory for baseband controlled phase gates in superconducting …
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Long-Term Ambient Noise Statistics in the Gulf of Mexico
… quantities are computed from the resulting eight time series of noise spectral level: mean, median, standard deviation, skewness, kurtosis and coherence time. Four hurricanes were recorded during the summer of 2004 and they have a major impact on all of the noise statistics. Noise levels at higher …
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Study of the effects of surface cladding on 3D transmon
… qubit. However they need improvements in their coherence time to create a viable quantum computing. In this work I study the effect on decoherence caused by two level systems in the native oxide that forms on the surface of qubit. To this end I fabricate 3D transmon qubits using materials grown …
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The silicon-vacancy centre in diamond for quantum information processing
… spin. This technique allows us to evaluate the coherence time of the dark state and hence of the spin, while demonstrating the possibility of all-optical control of the spin when a $\Lambda$-scheme is available. We then use resonant optical pulses to initialise and read out the spin state of a …
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High Fidelity Universal Gates Performed on a Continuously-Decoupled Coherence Enhanced Transmon Qubit
<p>Decoherence is the primary limiting factor for the utility of modern qubits and qubit networks; most chiefly, pure dephasing which limits the operational time any gate-sequence can produce a high-fidelity result. In this dissertation, I present the results of my experiment, performing fast, high …
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Error exponents for multipath fading channels : a strong coding theorem
… "peakiness", and fading parameters such as the coherence time. They can be used to compare peaky signaling to other large bandwidth systems over fading channels, such as ultrawide band (UWB) radio and wideband CDMA. We first derive an upper bound for general fading, then specialize to the case …
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Efficient and coherent frequency conversions and nonlinear interference in optical parametric and atomic Raman processes
… an interference experiment, we demonstrate that coherence is preserved in the conversion process. This technique could lead to a high-fidelity quantum state transfer from a high-frequency photon to a low-frequency photon and connect a missing link in quantum networks. ^ Coherent and efficient …
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Drone Cellular Networks: Fundamentals, Modeling, and Analysis
… of the spatial distribution of the UAVs over time. After performing these system-level analyses on UAV networks, we focus our attention on the air-to-ground wireless channel and attempt to understand its unique features. For that, we first study the impact of UAV wobbling on the coherence time …
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Frequency down-conversion for quantum networking with nitrogen-vacancy centers in diamond
… candidate for these memories because of its long coherence time and the ability to optically write to and read out information from its spin. However, the NV-center fluoresces in the visible range, which experiences strong losses (8 dB/km) in optical fiber and has limited the current distance …
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Microwave and optical control of sub-diffraction spin qubits in diamond at cryogenic temperatures
… efficiently enough in practice to overcome decoherence has been unsuccessful. In this thesis, I laid the ground work to entangle two NVs using a dipole coupling protocol, a protocol that has the advantageous property of not requiring use of identical photons, making this experimental approach …
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Quantum Information Processing with Color Center Qubits: Theory of Initialization and Robust Control
… optically-active spin qubits within the coherence time limit. Moreover, the nearby nuclear spins have long coherence times suitable for quantum memories. In this thesis, I present a theoretical understanding of and control protocols for various color centers. Using group theory, I explore …
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Mesoscopic quantum interference experiments in InGaAs and GaAs two-dimensional systems
… to explore mesoscopic physics and quantum decoherence. This dissertation focuses on two-dimensional (2D) electron systems in $delta-$Si doped n-type In$_{0.64}$Ga$_{0.36}$As/In$_{0.45}$Al$_{0.55}$As, 2D hole systems in Si-doped p-type GaAs/Al$_{0.35}$Ga$_{0.65}$As and C-doped p-type …
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Quantum Computation and Simulation using Fermion Pair Registers
… pairs are used to encode qubits exhibiting long coherence time and robustness against laser intensity noise. In this thesis, we propose and analyze a new approach for quantum computation and simulation, leveraging fermionic particles on optical lattices under quantum gas microscopes. We engineer …
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An injection-locked 674 nm laser for Strontium-88 ion trapping
… allows more computational operations within the coherence time of the system. The focus of this thesis is the design and construction of a more powerful laser to stimulate the qubit transition of the 88Sr+ ion, using injection-locking to stabilize the frequency of the new laser. Injection-locking …
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