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  • richardmitnick 4:47 pm on November 6, 2018 Permalink | Reply
    Tags: Physicists Race to Demystify Einstein’s ‘Spooky’ Science, , UCSD - University of Californa San Diego   

    From UC San Diego: “Physicists Race to Demystify Einstein’s ‘Spooky’ Science” 

    UC San Diego bloc

    From UC San Diego

    August 20, 2018

    Cynthia Dillon
    858-822-0142
    cdillon@ucsd.edu

    International research team recasts timeline, dating from the Big Bang, of possible quantum theory alternatives.

    When it comes to fundamental physics, things can get spooky. At least that’s what Albert Einstein said when describing the phenomenon of quantum entanglement—the linkage of particles in such a way that measurements performed on one particle seem to affect the other, even when separated by great distances. “Spooky action at a distance” is how Einstein described what he couldn’t explain.

    1
    Schematic of the 2018 “Cosmic Bell” experiment at the Roque de Los Muchachos Observatory in the Canary Islands, where two large telescopes observed the fluctuating color of light from distant quasars (red and blue galaxies). The green beams indicate polarization-entangled photons sent through the open air between stations separated by about one kilometer. Image by Andrew S. Friedman and Dominik Rauch.

    While quantum mechanics includes many mysterious phenomena like entanglement, it remains the best fundamental physical theory describing how matter and light behave at the smallest scales. Quantum theory has survived numerous experimental tests in the past century while enabling many advanced technologies: modern computers, digital cameras and the displays of TVs, laptops and smartphones. Quantum entanglement itself is also the key to several next-generation technologies in computing, encryption and telecommunications. Yet, there is no clear consensus on how to interpret what quantum theory says about the true nature of reality at the subatomic level, or to definitively explain how entanglement actually works.

    2
    Diagram of a run of the Cosmic Bell test. The regions of space and time where an alternative, non-quantum mechanism could still have acted (limited to the red and/or blue regions) corresponds to at least 7.78 billion years ago (blue region). Light from the more distant quasar was emitted 12.21 billion years ago (red region). Compared to the gray region, representing all of space and time prior to the experiment, the alternatives are limited to within four percent of the space-time volume since the Big Bang. Image by Andrew Friedman and David Leon.

    According to Andrew Friedman, a research scientist at the University of California San Diego Center for Astrophysics and Space Sciences (CASS), “the race is on” around the globe to identify and experimentally close potential loopholes that could still allow alternative theories, distinct from quantum theory, to explain perplexing phenomena like quantum entanglement. Such loopholes could potentially allow future quantum encryption schemes to be hacked. So, Friedman and his fellow researchers conducted a “Cosmic Bell” test with polarization-entangled photons designed to further close the “freedom-of-choice” or “free will” loophole in tests of Bell’s inequality, a famous theoretical result derived by physicist John S. Bell in the 1960s. Published in the Aug. 20 issue of Physical Review Letters, their findings are consistent with quantum theory and push back to at least 7.8 billion years ago the most recent time by which any causal influences from alternative, non-quantum mechanisms could have exploited the freedom-of-choice loophole.

    “Our findings imply that any such mechanism is excluded from explaining the results from within a whopping 96% of the space-time volume in the causal past of our experiment, stretching all the way from the Big Bang until today,” said Friedman. “While these alternatives to quantum theory have not been completely ruled out, we are pushing them into a progressively smaller corner of space and time.”

    In their experiment, the researchers outsourced the choice of entangled photon measurements to the universe. They did this by using the color of light that has been traveling to Earth for billions of years from distant galaxies—quasars—as a “cosmic random number generator.”

    “This is a rare experiment that comes along only very seldomly in a scientist’s career: a pioneering experiment that sets the bar so high few, if any, competitors can ever match it,” noted UC San Diego astrophysicist Brian Keating. “I’m so proud that my graduate student David Leon had the chance to make a significant contribution to this fascinating research, co-led by CASS research scientist, Dr. Andrew Friedman.”

    Besides UC San Diego’s Friedman and Leon, the full research team included lead author and Ph.D. student Dominik Rauch, along with Anton Zeilinger and his experimental quantum optics group from the University of Vienna; theoretical physicists David Kaiser and Alan Guth at MIT; Jason Gallicchio and his experimental physics group at Harvey Mudd College, and others. Expanding upon their previous quantum entanglement experiments [Physical Review Letters], Friedman and colleagues went to great effort to choose entangled particle measurements using 3.6 and 4.2 meter telescopes in the Canary Islands, allowing them to collect sufficient light from the much fainter, distant quasars.

    To conduct their test, they shined laser light into a special crystal that generated pairs of entangled photons, which the scientists repeatedly sent through the open air toward both telescopes. From the quasar light collected, the scientists could choose polarization measurement settings while each entangled photon was in mid-flight. The group was allotted three nights and a few hours at the Roque de los Muchachos Observatory in La Palma, amidst operationally challenging conditions including freezing rain, high winds, and uncertainty about whether they would have enough time to complete the experiment. Additionally, Friedman and colleagues had to write software that could choose the best quasars to observe on-the-fly—from a database of more than 1.5 million—and predict the observation time needed to obtain a statistically significant result.

    “We pushed to the limit what could be done within the time constraints,” said Friedman. “The experiment would not have been possible without an amazing international collaboration. It was a roller coaster experience to see it actually work.”

    The research was funded by the Austrian Academy of Sciences; The Austrian Science Fund with SFB F40 (FOQUS) and project COQuS (W1210-N16); the Austrian Federal Ministry of Education, Science and Research; the University of Vienna (via the project QUESS); the National Science Foundation INSPIRE Grant (PHY-1541160); the U.S. Department of Energy (DE-SC0012567); the U.S. Department of Defense, through the National Defense Science & Engineering Graduate Fellowship Program, and UC San Diego’s Ax Center for Experimental Cosmology.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    UC San Diego Campus

    The University of California, San Diego (also referred to as UC San Diego or UCSD), is a public research university located in the La Jolla area of San Diego, California, in the United States.[12] The university occupies 2,141 acres (866 ha) near the coast of the Pacific Ocean with the main campus resting on approximately 1,152 acres (466 ha).[13] Established in 1960 near the pre-existing Scripps Institution of Oceanography, UC San Diego is the seventh oldest of the 10 University of California campuses and offers over 200 undergraduate and graduate degree programs, enrolling about 22,700 undergraduate and 6,300 graduate students. UC San Diego is one of America’s Public Ivy universities, which recognizes top public research universities in the United States. UC San Diego was ranked 8th among public universities and 37th among all universities in the United States, and rated the 18th Top World University by U.S. News & World Report ‘s 2015 rankings.

     
  • richardmitnick 10:54 am on February 16, 2018 Permalink | Reply
    Tags: , , Study ocean currents and the tiny creatures they transport, Swarm of Underwater Robots Mimics Ocean Life, UCSD - University of Californa San Diego   

    From Scripps Institution of Oceanography: “Swarm of Underwater Robots Mimics Ocean Life” Jan 2017 

    Scripps Institution of Oceanography

    Jan 24, 2017 [Just found this]

    Mario Aguilera
    858-534-3624
    scrippsnews@ucsd.edu

    1
    Miniature autonomous underwater explorers.

    Underwater robots developed by researchers at Scripps Institution of Oceanography at the University of California San Diego offer scientists an extraordinary new tool to study ocean currents and the tiny creatures they transport. Swarms of these underwater robots helped answer some basic questions about the most abundant life forms in the ocean—plankton.

    Scripps research oceanographer Jules Jaffe designed and built the miniature autonomous underwater explorers, or M-AUEs, to study small-scale environmental processes taking place in the ocean. The ocean-probing instruments are equipped with temperature and other sensors to measure the surrounding ocean conditions while the robots “swim” up and down to maintain a constant depth by adjusting their buoyancy. The M-AUEs could potentially be deployed in swarms of hundreds to thousands to capture a three-dimensional view of the interactions between ocean currents and marine life.

    In a new study published in the Jan. 24 [2017] issue of the journal Nature Communications, Jaffe and Scripps biological oceanographer Peter Franks deployed a swarm of 16 grapefruit-sized underwater robots programmed to mimic the underwater swimming behavior of plankton, the microscopic organisms that drift with the ocean currents. The research study was designed to test theories about how plankton form dense patches under the ocean surface, which often later reveal themselves at the surface as red tides.

    “These patches might work like planktonic singles bars,” said Franks, who has long suspected that the dense aggregations could aid feeding, reproduction, and protection from predators.

    Two decades ago Franks published a mathematical theory predicting that swimming plankton would form dense patches when pushed around by internal waves—giant, slow-moving waves below the ocean surface. Testing his theory would require tracking the movements of individual plankton—each smaller than a grain of rice—as they swam in the ocean, which is not possible using available technology.

    Jaffe instead invented “robotic plankton” that drift with the ocean currents, but are programmed to move up and down by adjusting their buoyancy, imitating the movements of plankton. A swarm of these robotic plankton was the ideal tool to finally put Franks’ mathematical theory to the test.

    “The big engineering breakthroughs were to make the M-AUEs small, inexpensive, and able to be tracked continuously underwater,” said Jaffe. The low cost allowed Jaffe and his team to build a small army of the robots that could be deployed in a swarm.

    Tracking the individual M-AUEs was a challenge, as GPS does not work underwater. A key component of the project was the development by researchers at UC San Diego’s Qualcomm Institute and Department of Computer Science and Engineering of mathematical techniques to use acoustic signals to track the M-AUE vehicles while they were submerged.

    During a five-hour experiment, the Scripps researchers along with UC San Diego colleagues deployed a 300-meter (984-foot) diameter swarm of 16 M-AUEs programmed to stay 10-meters (33-feet) deep in the ocean off the coast of Torrey Pines, near La Jolla, Calif. The M-AUEs constantly adjusted their buoyancy to move vertically against the currents created by the internal waves. The three-dimensional location information collected every 12 seconds revealed where this robotic swarm moved below the ocean surface.

    The results of the study were nearly identical to what Franks predicted. The surrounding ocean temperatures fluctuated as the internal waves passed through the M-AUE swarm. And, as predicted by Franks, the M-AUE location data showed that the swarm formed a tightly packed patch in the warm waters of the internal wave troughs, but dispersed over the wave crests.

    “This is the first time such a mechanism has been tested underwater,” said Franks.

    The experiment helped the researchers confirm that free-floating plankton can use the physical dynamics of the ocean—in this case internal waves—to increase their concentrations to congregate into swarms to fulfill their fundamental life needs.

    “This swarm-sensing approach opens up a whole new realm of ocean exploration,” said Jaffe. Augmenting the M-AUEs with cameras would allow the photographic mapping of coral habitats, or “plankton selfies,” according to Jaffe.

    The research team has hopes to build hundreds more of the miniature robots to study the movement of larvae between marine protected areas, monitor harmful red tide blooms, and to help track oil spills. The onboard hydrophones that help track the M-AUEs underwater could also allow the swarm to act like a giant “ear” in the ocean, listening to and localizing ambient sounds in the ocean.

    Jaffe, Franks, and their colleagues were awarded nearly $1 million from the National Science Foundation in 2009 to develop and test the new breed of ocean-probing instruments. The study’s coauthors include: Paul Roberts, principal development engineer at Scripps, Ryan Kastner, professor in the Department of Computer Science and Engineering; Diba Mirza, postdoctoral researcher in computer science; and Curt Schurgers, principal development engineer at the Qualcomm Institute, and Scripps student intern Adrien Boch.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    A department of UC San Diego, Scripps Institution of Oceanography is one of the oldest, largest, and most important centers for ocean, earth and atmospheric science research, education, and public service in the world.

    Research at Scripps encompasses physical, chemical, biological, geological, and geophysical studies of the oceans, Earth, and planets. Scripps undergraduate and graduate programs provide transformative educational and research opportunities in ocean, earth, and atmospheric sciences, as well as degrees in climate science and policy and marine biodiversity and conservation.

     
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