10 research outputs found
Application of Modular Multilevel Converter technology to HV power supplies of Neutral Beam injector
Evaluation of the possible application of Modular Multilevel Converter at the AGPS of NBI
Sixteenth Space Simulation Conference Confirming Spaceworthiness Into the Next Millennium
The conference provided participants with a forum to acquire and exchange information on the state of the art in space simulation, test technology, thermal simulation and protection, contamination, and techniques of test measurements
Above Bandgap Hyperpolarization Mechanism in Isotopically Purified Silicon and Optimal Bayesian Experiment Design for Estimation
This thesis is concerned with the mechanism underlying the above bandgap illumination Dynamic Nuclear Polarization (DNP) of phosphorus donors in isotopically purified silicon-28. Two proposed DNP models are introduced and compared. A series of NMR saturation experiments are performed in which modified buildup dynamics are observed when the saturation tone is applied at the bare phosphorus resonance. This effect is attributed to the phosphorus donor being ionized via the Auger process resulting in dynamics which are modelled as a set of coupled Bloch equations. The donor bound exciton capture and neutralization rates are extracted, and a paramagnetic shift of the bare phosphorus resonance is observed. These observed dynamics strongly imply the DNP mechanism is due to phononic modulation of the donor electron spatial wavefunction inducing cross-relaxation between the hyperfine coupled electron and nuclear spins.
The framework of Bayesian parameter estimation and its Sequential Monte Carlo(SMC) numerical implementation for continuous outcome probability distributions are introduced. Next, an introduction to Bayesian experiment design and its incorporation within the SMC framework is provided. A discussion of the computational challenges for continuous outcome distributions is given. To resolve these difficulties Monte Carlo Maximum Importance Sampling(MIS) numerical methods are developed which allow the evaluation of Bayesian experimental design heuristics such as the Bayes risk. These design strategies are applied to the problem of relaxation rate estimation with inversion recovery experiments. Experiments are optimized both respect to per-experiment performance and total experiment time. These techniques are shown to have substantial improvements over baseline methods. Furthermore, they compare favourably with previous frequentist experimental designs for IR experiments and demonstrate significant improvements
Towards many-body physics with Rydberg-dressed cavity polaritons
An exciting frontier in quantum information science is the creation and manipulation of
bottom-up quantum systems that are built and controlled one by one. For the past 30
years, we have witnessed signi cant progresses in harnessing strong atom- eld interactions
for critical applications in quantum computation, communication, simulation, and metrology.
By extension, we can envisage a quantum network consisting of material nodes coupled
together with in nite-dimensional bosonic quantum channels. In this context, there
has been active research worldwide to achieve quantum optical circuits, for which single
atoms are wired by freely-propagating single photons through the circuit elements. For all
these systems, the system-size expansion with atoms and photons results in a fundamental
pathologic scaling that linearizes the very atom- eld interaction, and signi cantly limits
the degree of non-classicality and entanglement in analog atom- eld quantum systems for
atom number N 1.
The long-term motivation of this MSc thesis is (i) to discover new physical mechanisms
that extend the inherent scaling behavior of atom- eld interactions and (ii) to
develop quantum optics toolkits that design dynamical gauge structures for the realization
of lattice-gauge-theoretic quantum network and the synthesis of novel quantum optically
gauged materials. The basic premise is to achieve the strong coupling regime for a quantum
many-body material system interacting with the quantized elds of an optical cavity. Our
laboratory e ort can be described as the march towards \many-body QED," where optical
elds acquire some properties of the material interactions that constrain their dynamical
processes, as with quantum eld theories. While such an e ort currently do not exist elsewhere,
we are convicted that our work will become an essential endeavor to enable cavity
quantum electrodynamics (QED) in the bona- de regime of quantum many-body physics
in this entanglement frontier.
In this context, I describe an example in Chapter 2 that utilizes strong RydbergRydberg
interactions to design dynamical gauge structures for the quantum square ice
models. Quantum
uctuations driven by cavity-mediated in nite-range interaction stabilize
the quantum-gauged system into a long-range entangled quantum spin liquid that may
be detected through the time-ordered photoelectric statistics for photons leaking out of the
cavity. Fractionalized \spinon" and \vison" excitations can be manipulated for topological
quantum computation, and the emergent photons of arti cial QED in our lattice gauge
theoretic system can be directly measured and studied.
The laboratory challenge towards strongly coupled cavity Rydberg polaritons encompasses
three daunting research milestones that push the technological boundaries beyond of the state-of-the-arts. In Chapter 3, I discuss our extreme-high-vacuum chamber (XHV)
cluster system that allows the world's lowest operating vacuum environment P ' 10
Torr for an ultracold AMO experiment with long background-limited trap lifetimes. In
Chapter 4, I discuss our ultrastable laser systems stabilized to the ultra-low-expansion
optical cavities. Coupled with a scalable eld-programmable-gate-array (FPGA) digitalanalog
control system, we can manipulate arbitrarily the phase-amplitude relationship of
several dozens of laser elds across 300 nm to 1550 nm at mHz precision. In Chapter 5,
we discuss the quantum trajectory simulations for manipulating the external degrees of
freedom of ultracold atoms with external laser elds. Electrically tunable liquid crystal
lens creates a dynamically tunable optical trap to move the ultracold atomic gases over
long distance within the ultra-high-vacuum (UHV) chamber system.
In Chapter 6, I discuss our collaborative development of two science cavity platforms
{ the \Rydberg" quantum dot and the many-body QED platforms. An important development
was the research into new high-index IBS materials, where we have utilized our
low-loss optical mirrors for extending the world's highest cavity nesse F 500k! We discuss
the unique challenges of implementing optical cavity QED for Rydberg atoms, which
required tremendous degrees of electromagnetic shielding and eld control. Single-crystal
Sapphire structure, along with Angstrom-level diamond-turned Ti blade electrodes, is utilized
for the eld compensation and extinction by > 60 dB. Single-crystal PZTs on silica
V-grooves are utilized for the stabilization of the optical cavity with length uncertainty less
than 1=100 of a single nucleon, along with extreme level of vibration isolation in a XHV
environment. The capability to perform in-situ RF plasma cleaning allows the regeneration
of optical mirrors when coated with a few Cs atoms. Lastly but not the least, we combine
single-atom resolution quantum gas microscopy technique with superpixel holographic algorithm
to project arbitrary real-time recon gurable di raction-limited optical potential
landscapes for the preparation of low-entropy atom arrays
Voice Broadcast Mission Study /VMBS/ Volume 2 - Study report Final report
Voice broadcasting mission stud
Energy. A continuing bibliography with indexes, issue 18
This issue of Energy lists 1038 reports, journal articles, and other documents announced between April 1, 1978 and June 30, 1978 in Scientific and Technical Aerospace Reports (STAR) or in International Aerospace Abstracts (IAA). The coverage includes regional, national and international energy systems; research and development on fuels and other sources of energy; energy conversion, transport, transmission, distribution and storage, with special emphasis on use of hydrogen and of solar energy. Also included are methods of locating or using new energy resources. Of special interest is energy for heating, lighting, for powering aircraft, surface vehicles, or other machinery
Cumulative index to NASA Tech Briefs, 1970-1975
Tech briefs of technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Abstracts and indexes of subject, personal author, originating center, and tech brief number for the 1970-1975 tech briefs are presented
Aeronautical Engineering - A special bibliography with indexes /supplement 1/
Annotated reference bibliography on aeronautical engineering document