https://joewiedemann.info/categories/publications/Recent content in Publications on Joe WiedemannHugoen-usFri, 18 Apr 2025 00:00:00 +0000https://joewiedemann.info/publications/pxs-graphite/Fri, 18 Apr 2025 00:00:00 +0000https://joewiedemann.info/publications/pxs-graphite/<h2 id="abstract">Abstract</h2> <p>We describe a passive heat switch based on a commercial pyrolytic graphite sheet. Measurements of the thermal conductivity of the graphite are presented, confirming a large difference between room temperature and ≈4 K. The implementation of a graphite heat switch in a cryostat operating a 3He/4He sorption refrigerator is demonstrated.</p> <h2 id="achievements">Achievements</h2> <ul> <li>Improved the cooldown time for the 3He stage by 50% with inexpensive graphite sheet</li> <li>Demonstrated the &lsquo;off&rsquo; state of the switch applied only microwatts of heat load</li> <li>Proved durability through 10+ room temperature-cryogenic cycles</li> <li>Able to reduce the number of expensive gas-gap heat switches needed to conduct experiment</li> </ul> <h2 id="links">Links</h2> <ul> <li><a href="https://doi.org/10.1016/j.cryogenics.2025.104079">DOI</a></li> </ul> <h2 id="related-projects">Related Projects</h2> <p>This publication is based on research conducted in <a href="https://joewiedemann.info/research/pxs-cryogenics/">PXS Cryogenics</a>.</p>https://joewiedemann.info/publications/rydberg-rades/Mon, 10 Jun 2024 00:00:00 +0000https://joewiedemann.info/publications/rydberg-rades/<h2 id="summary">Summary</h2> <p>This publication presents work on Rydberg atom dark evolution sensing (RADES), demonstrating the achievement of 10nV/cm/√Hz sensitivity at 10GHz. The research utilized time-separated field procedures to establish new sensitivity standards for Rydberg atom electrometry.</p> <h2 id="key-contributions">Key Contributions</h2> <ul> <li>Demonstrated Rydberg atom dark evolution sensing (RADES) achieving unprecedented electric field sensitivity</li> <li>Decoupled sensitivity gains from laser linewidths by exploiting coherence time of cesium rydberg states</li> <li>Technique applies to thermal atomic vapors</li> <li>Demonstrated 3 microsecond long Rabi precession in the microwave field</li> </ul> <h2 id="related-research">Related Research</h2> <p>This publication is based on research conducted in the <a href="https://joewiedemann.info/research/rydberg-rades/">Rydberg Atom Dark Evolution Sensing (RADES)</a> project.</p>https://joewiedemann.info/publications/oam-scintillation/Sun, 01 Mar 2020 00:00:00 +0000https://joewiedemann.info/publications/oam-scintillation/<h2 id="summary">Summary</h2> <p>This work found preliminary evidence that imparting orbital angular momentum onto Gaussian-mode laser beams can weakly improve their intensity stability in atmospheric turbulence. The experiment required building an 890-meter optical link across the Severn River and co-aligning it with a scintillometer to characterize the atmosphere during each measurement.</p> <h2 id="key-contributions">Key Contributions</h2> <ul> <li>Compared a Gaussian beam with OAM beams carrying topological charges of 1, 6, and 8</li> <li>Measured beam scintillation across a real near-maritime link under varied atmospheric conditions</li> <li>Observed a weak reduction in scintillation index as topological charge increased</li> <li>Identified the additional measurement scale needed to improve statistical significance</li> </ul> <h2 id="link-to-work">Link to Work</h2> <ul> <li><a href="https://doi.org/10.1016/j.optcom.2019.124836">DOI</a></li> </ul> <h2 id="related-work">Related Work</h2> <p>This publication is from the <a href="https://joewiedemann.info/research/oam-scintillation/">Scintillation of Laser Beams Carrying Orbital Angular Momentum</a> project.</p>