2,375 research outputs found
2023-2024 Catalog
The 2023-2024 Governors State University Undergraduate and Graduate Catalog is a comprehensive listing of current information regarding:Degree RequirementsCourse OfferingsUndergraduate and Graduate Rules and Regulation
Introduction to Psychology
Introduction to Psychology is a modified version of Psychology 2e - OpenStax
Developing a Microwave Quantum Memory with Rare-Earth Doped Crystals
Rare-earth doped crystals have attracted a significant amount of attention for
use in quantum systems. Available, long-lived, optical and microwave transitions
has lead to proposals for quantum transduction and quantum memories, both of
which are important in building large scale quantum networks. Ensembles of
rare-earth spins can be coupled to superconducting resonators, and high coupling
strengths (with cooperativity > 1) readily achievable. While such systems have
been constructed, a useful quantum memory which exploits highly coherent transitions has not yet been developed in the microwave domain. In this thesis we couple
high-Q superconducting resonators to Yb doped YSO. The spin system of Yb:YSO
is explored and the main causes of decoherence are outlined, these are found to
be instantaneous diffusion and spectral diffusion. In the process of this, new techniques are developed to determine decoherence sources, where nuclear spins within
the YSO crystal are found to limit coherence.
Two different regimes are explored to increase the coherence time. Using optimal field orientations and high magnetic field magnitudes, the coherence time is
extended to (6±2) ms. While the zero field clock transition is used, along with isotopic purification, to reach the same time ((6±1) ms). Using these techniques to increase coherence, the foundations for a microwave quantum memory with Yb:YSO
are laid. Cooperativities > 1 are measured for three different Yb spin systems, this
allows for these spin systems to be used in memory protocols and reach unit efficiency. New pulse sequences using adiabatic fast passage are developed to provide
control over the spin ensemble and for memory protocols.
Finally, we use the knowledge from all of these studies to propose a system
which would form the basis of an efficient, long-lived microwave quantum memory
using FIB-milled Yb:YSO
Memory Effect and Carroll Symmetry: 50 years after
Particles at rest before the arrival of a burst of gravitational wave move,
after the wave has passed, with constant velocity along diverging geodesics. As
recognized by Souriau 50 years ago and then forgotten, their motion is
particularly simple in Baldwin-Jeffery-Rosen (BJR) coordinates (which are
however defined in coordinate pathches only) by using the first integrals
associated with the 5-parameter isometry group, recently identified as
L\'evy-Leblond's ``Carroll'' group with broken rotations. The description in
terms of Brinkmann coordinates is global however requires to solve a
Sturm-Liouville equation which we can do in general only numerically. The
relation between BJR and Brinkmann requires in turn to solve yet another
Sturm-Liouville equation. The theory is illustrated by geodesic motion in a
linearly polarized (approximate) ``sandwich'' wave proposed by Gibbons and
Hawking for gravitational collapse, and by circularly polarized approximate
sandwich waves with Gaussian envelope.Comment: Considerably extended version. 50 pages, with many figure
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