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Thursday, May 26, 2016

The Cat is Big and Smart: A Second Box for Schrödinger's Cat?

      "Schrödinger's cat is a well-known paradox that applies the concept of superposition in quantum physics to objects encountered in everyday life. The idea is that a cat is placed in a sealed box with a radioactive source and a poison that will be triggered if an atom of the radioactive substance decays. Quantum physics suggests that the cat is both alive and dead (a superposition of states), until someone opens the box and, in doing so, changes the quantum state."

      "This hypothetical experiment, envisioned by one of the founding fathers of quantum mechanics in 1935, has found vivid analogies in laboratories in recent years. Scientists can now place a wave-packet of light composed of hundreds of particles simultaneously in two distinctly different states. Each state corresponds to an ordinary (classical) form of light abundant in nature."

     "A team of Yale scientists created a more exotic type of Schrödinger's cat-like state that has been proposed for experiments for more than 20 years. This cat lives or dies in two boxes at once, which is a marriage of the idea of Schrödinger's cat and another central concept of quantum physics: entanglement. Entanglement allows a local observation to change the state of a distant object instantaneously. Einstein once called it "spooky action at a distance," and in this case it allows a cat state to be distributed in different spatial modes."

     "The Yale team built a device consisting of two, 3D microwave cavities and an additional monitoring port -- all connected by a superconducting, artificial atom. The "cat" is made of confined microwave light in both cavities."

     "This cat is big and smart. It doesn't stay in one box because the quantum state is shared between the two cavities and cannot be described separately," said Chen Wang, a postdoctoral associate at Yale and first author of a study in the journal Science, describing the research. "One can also take an alternative view, where we have two small and simple Schrodinger's cats, one in each box, that are entangled."

     "The research also has potential applications in quantum computation. A quantum computer would be able to solve certain problems much faster than classical computers by exploiting superposition and entanglement. Yet one of the main problems in developing a reliable quantum computer is how to correct for errors without disturbing the information.

     "It turns out 'cat' (or dog ;-)) states are a very effective approach to storing quantum information redundantly, for implementation of quantum error correction. Generating a cat in two boxes is the first step towards logical operation between two quantum bits in an error-correctible manner," said co-author Robert Schoelkopf, Sterling Professor of Applied Physics and Physics, and director of the Yale Quantum Institute."

     "Schoelkopf and his frequent collaborators, Michel Devoret and Steve Girvin, have pioneered the field of circuit quantum electrodynamics (cQED), providing one of the most widely used frameworks for quantum computation research. Devoret, Yale's F.W. Beinecke Professor of Physics, and Girvin, Yale's Eugene Higgins Professor of Physics and Applied Physics, are co-authors of the paper."

     "The research builds upon more than a decade of development in cQED architecture. The Yale team designed a variety of new features, including cylindrical 3D cavities with record quantum information storage time of more than 1 millisecond in superconducting circuits, and a measurement system that monitors certain aspects of a quantum state in a precise, non-destructive way. "We have combined quite a lot of recent technologies here," Wang said in Science.

Wednesday, May 18, 2016

May 18, 1980: Where were you when Mt St Helens Exploded?

     May 18, 1980, was a remarkable day for me and almost every geologist I know.  We identified with David A Johnston, the geologist killed in the volcanic event. The explosion and subsequent landslide of the north face of Mt. St. Helens in Washington state, USA, was top news throughout that day and ensuing weeks and months.

      The USGS put together still photos to create this video of one of the largest (if not the largest) landslides ever on earth.

     An earthquake at 8:32 a.m. local time on Sunday, May 18, 1980, caused the entire weakened north face to slide away. This suddenly exposed the partly molten gas- and steam-rich rock in the volcano to lower pressures. The rock responded by exploding a hot mix of lava and pulverized older rock toward Spirit Lake so fast that it overtook the avalanching north face.

         An eruption column rose 80,000 feet into the atmosphere and deposited ash in 11 U.S. states. A USGS friend brought back vials of varying sized ash collected after the explosion.

        At the same time, snow, ice and several entire glaciers on the volcano melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly 50 miles to the southwest. 

       Individual trees in the direct path of the blast were charred. . .

and trees were caught up in the mudflows.

      Downed logs still remain as in this 2012 photograph:

What are your memories of that day? Were you nearby, perchance?


Thursday, May 12, 2016

Magnetic Reconnection: Magnetospheric Multiscale (MMS) Mission

      "Most people do not give much thought to the Earth's magnetic field, yet it is every bit as essential to life as air, water and sunlight. The magnetic field provides an invisible, but crucial, barrier that protects Earth from the sun's magnetic field, which drives a stream of charged particles known as the solar wind outward from the sun's outer layers. The interaction between these two magnetic fields can cause explosive storms in the space near Earth, which can knock out satellites and cause problems here on Earth's surface, despite the protection offered by Earth's magnetic field."

      "A new study co-authored by University of Maryland physicists provides the first major results of NASA's Magnetospheric Multiscale (MMS) mission, including an unprecedented look at the interaction between the magnetic fields of Earth and the sun. The paper describes the first direct and detailed observation of a phenomenon known as magnetic reconnection, which occurs when two opposing magnetic field lines break and reconnect with each other, releasing massive amounts of energy."

      "The discovery is a major milestone in understanding magnetism and space weather. The research paper appears in the May 13, 2016, issue of the journal Science."

     "Imagine two trains traveling toward each other on separate tracks, but the trains are switched to the same track at the last minute," said James Drake, a professor of physics at UMD and a co-author on the Science study. "Each track represents a magnetic field line from one of the two interacting magnetic fields, while the track switch represents a reconnection event. The resulting crash sends energy out from the reconnection point like a slingshot." 

      "Evidence suggests that reconnection is a major driving force behind events such as solar flares, coronal mass ejections, magnetic storms, and the auroras observed at both the North and South poles of Earth. Although researchers have tried to study reconnection in the lab and in space for nearly half a century, the MMS mission is the first to directly observe how reconnection happens."

     "The MMS mission provided more precise observations than ever before. Flying in a pyramid formation at the edge of Earth's magnetic field with as little as 10 kilometers' distance between four identical spacecraft, MMS images electrons within the pyramid once every 30 milliseconds. In contrast, MMS' predecessor, the European Space Agency and NASA's Cluster II mission, takes measurements once every three seconds--enough time for MMS to make 100 measurements."

     "Just looking at the data from MMS is extraordinary. The level of detail allows us to see things that were previously a blur," explained Drake, who served on the MMS science team and also advised the engineering team on the requirements for MMS instrumentation. "With a time interval of three seconds, seeing reconnection with Cluster II was impossible. But the quality of the MMS data is absolutely inspiring. It's not clear that there will ever be another mission quite like this one."

     "Simply observing reconnection in detail is an important milestone. But a major goal of the MMS mission is to determine how magnetic field lines briefly break, enabling reconnection and energy release to happen. Measuring the behavior of electrons in a reconnection event will enable a more accurate description of how reconnection works; in particular, whether it occurs in a neat and orderly process, or in a turbulent, stormlike swirl of energy and particles.

     "A clearer picture of the physics of reconnection will also bring us one step closer to understanding space weather--including whether solar flares and magnetic storms follow any sort of predictable pattern like weather here on Earth. Reconnection can also help scientists understand other, more energetic astrophysical phenomena such as magnetars, which are neutron stars with an unusually strong magnetic field.

        "Reconnection in Earth's magnetic field is relatively low energy, but we can get a good sense of what is happening if we extrapolate to more energetic systems," said Mark Swisdaku. "The edge of Earth's magnetic field is an excellent test lab, as it's just about the only place where we can fly a spacecraft directly through a region where reconnection occurs."

      "To date, MMS has focused only on the sun-facing side of Earth's magnetic field. In the future, the mission is slated to fly to the opposite side to investigate the teardrop-shaped tail of the magnetic field that faces away from the sun."

Quite exciting, eh?

Wednesday, May 4, 2016

"Written" to the Core: A Core A Day

      Sediment coring from the bottom of the world's oceans includes miles of sediment and rock preserved at the USGS Repository here in Golden, CO, USA, as well as places like the Lamont-Doherty Core Repository.

     "Lamont has been actively collecting and archiving sediment from around the world . This is in large part due to Lamont's first director, Maurice Ewing, who instilled a philosophy of "A core a day" for all ocean research vessels. Ewing firmly believing that if we had the sediment we would be able to piece together patterns and stories about our planet, so every day at noon, or thereabouts, the ship would collect a core."

 The cores are used to reveal stories of earth systems, including those of climate cycles. Almost 40 years have passed since the groundbreaking work of the CLIMAP group that used the cores to connect the start of Earth's glacial cycles to changes in eccentricity, precession and tilt. (Hayes, Imbrie and Shackleton, 1976) . Collecting sediment on this Arctic GEOTRACES cruise will help scientists understand more of the stories locked in the oceans. 

    " The length of a core is dictated by the goal of the collection. Early Lamont cores were more about collecting just to gather the material because the ship was there. These early core were generally 6 to 9 meters long, although one incredibly long 28.2 meter core was collected from the Central Pacific. "

      For the sampling GEOTRACES is doing in the Arctic there is a specific goal of collecting just the top few dozen centimeters of sediment and the water just above it, yet at a depth of about 2200 meters. This will require a much different technique than what was used for the long Central Pacific core.

     "The sediment in this region is soft, so the plan was to drop a small general-purpose device called a Mono-corer over the side of the ship with a few small weights on top to help drive the core tube in straight."

     "The corer would hang below the bottom of the rosette of water samplers, far enough below that the rosette would remain 'mud-free' but still able to collect near bottom water samples. The mud in the mono-corer would be held in place by a spring-loaded door that snapped closed once the mud was inside and the tube began its return trip to the ship."

     You can read more about this technique, including the "Cone of Silence" here.

      I have two connections to these cores: a summer spent coring in the Mediterranean Sea on Duke University's Research Vessel Eastward and living in Lamont House (dorm) at Smith College, MA, USA.

       It was a fun summer.  What was your favorite educational summer?

Inspired to the core,