archive-edu.com » EDU » C » COLORADO.EDU

Total: 304

Choose link from "Titles, links and description words view":

Or switch to "Titles and links view".
  • No free lunch for entangled particles | JILA-PFC
    the quantum properties of entanglement and superposition Superposition is a state in which a particle holds two different properties such as red and blue or spin up or spin down at the same time Once particles in a superposition state are entangled with one another it s possible to obtain much more information by measuring a whole group of correlated particles than by measuring any single particle Unfortunately measuring entangled superposition states can destroy them Because the particles are linked together if you measure one particle to determine if it is red or blue for example the other one knows This knowing causes the particles to lose their entanglement and superposition in other words they become normal independent particles with a single property i e one is red the other blue One way for an entangled state to be more robust is if there is a big step in energy between the entangled state and the rest of the world With such a large energy gap little nudges to the entangled state are less likely to destroy it But there s a problem here too The more particles in the entangled state the smaller the protective energy gap Thus the challenge is to find a way to make entangled states with enough particles to be useful but with an energy gap sufficiently wide to protect it from destruction One common way to make entangled states is to place atoms in an optical trap shaped like a donut or toroid Figure 1 Atoms are trapped at certain locations within that toroid by a criss crossing pattern of laser beams that create comfortable resting places for the atoms as shown in the figure If the optical trap is then rotated the atoms naturally rotate along However because of the strange nature of

    Original URL path: http://jila-pfc.colorado.edu/highlights/no-free-lunch-entangled-particles (2016-04-29)
    Open archived version from archive


  • Schrödinger Cats Light the Way | JILA-PFC
    glass by looking at the transmitted sunlight on the other side In the laboratory scientists can vary aspects of the probe laser such as its color and intensity or how long it shines on the sample But there is more to light than these familiar wave like properties A beam of light can also be seen as a stream of particles called photons which have hidden and often strange quantum mechanical properties For instance we do not yet have the technological capability look inside light and see superpositions of different intensities And accurate theoretical predictions are challenging in complicated systems like semiconductors Consequently researchers have remained in the dark about how these properties of light might affect spectroscopy experiments To illuminate the effects of light s quantum features Cundiff and his colleagues have been working on developing a new type of spectroscopy Since they can t tune a laser to emit light with particular quantum properties they instead measure a sample s response as the light intensity from a typical laser is varied Using this information and theory developed by the group at Marburg University they back calculate how the system would respond if they had manipulated the quantum nature of the light in what is called a Schrödinger Cat state Figure 1 This technique works because light in a Schrödinger Cat state can be mathematically reconstructed by adding together two different intensities of normal laser light But here s where the quantum weirdness comes in If we could make a detector that could measure the intensity of Schrödinger Cat light it either would measure one of two intensities or the other but not something in between Like the mythical cat of the same name which is simultaneously both alive and dead until you open the box Schrödinger Cat light

    Original URL path: http://jila-pfc.colorado.edu/highlights/schr%C3%B6dinger-cats-light-way (2016-04-29)
    Open archived version from archive

  • Quantum Body Swapping | JILA-PFC
    widely accepted theory said that a strong laser field would make it easier for the lone electron to escape when the ion was stretched apart as opposed to contracted Thus the strength of the laser field was supposed to correspond to a high probability of the loss of the remaining electron in a process known as ionization Takemoto and Becker were just going to fill in a few details in this story But to their surprise their analysis revealed multiple bursts of ionization during one half of the oscillation of the laser electric field including one burst earlier than expected and another later than expected The later of the two extra bursts occurred when the lone electron temporarily and somewhat randomly surrounded one of the protons This strange behavior appeared to be induced by the laser pulse itself About the time Becker and Takemoto were getting ready to send off an article to Physical Review Letters on the strange ionization behavior in H 2 Becker s friend Reinhard Dörner of the Institut für Kernphysik at Germany s J W Goethe Universität contacted Becker reporting that his experimental lab was studying the ionization of H 2 and H 2 is doing something crazy Yes I know Becker responded He explained what their theoretical study had shown and agreed to enhance the new theory to take account of the particular experimental conditions in Dörner s lab The goal was to further explain the strange quantum swapping of the lone electron between the ion s two protons Because this quantum body swapping had been observed in both theory and experiment the researchers were fairly sure it was real It took Takemoto and Becker a year to complete their enhanced theoretical analysis that closely mirrored the German experiment which had used a more complicated

    Original URL path: http://jila-pfc.colorado.edu/highlights/quantum-body-swapping (2016-04-29)
    Open archived version from archive

  • Cross-Cultural Spectroscopy | JILA-PFC
    become a more well rounded biophysics researcher Lubbeck s project was the study of the response of red fluorescent proteins to ultrafast laser light Red fluorescent proteins are derived from sea anemones and coral They have a barrel shaped symmetric structure that surrounds and protects a color producing entity chromophore that fluoresces red Figure 2 Because developing a more stable red fluorescent protein is her thesis project Lubbeck was able to overnight samples from the Jimenez lab to Riken for use in her summer project At RIKEN I primarily used spectroscopy to see which areas of the protein moved the most when the chromophore was excited by the laser Lubbeck said I was especially interested finding out if some red fluorescent proteins were more flexible than others because increased flexibility of the part of the protein holding the chromophore could indicate a structural weakness In the process of learning to make careful measurements of time dependent protein spectra Lubbeck was also able to introduce some biophysics techniques to her lab mates It was a good exchange Lubbeck reflects now on her 10 week summer program which began with a week of orientation at the Sodenkai Institute in Hayama Kanagawa prefecture Her orientation included classes in Japanese language musical instruments and tea ceremony At the end of orientation she stayed with a local family who introduced her to Karaoke and took her to see the sights of Kamakura After orientation Lubbeck spent most of the next nine weeks working on her spectroscopy project at RIKEN Her RIKEN colleagues did take her to a weeklong scientific conference conducted in English on the island of Hokkaido Back at RIKEN Lubbeck was able to collect good data on her red fluorescent protein by working really hard typically from 10 a m to 11 p

    Original URL path: http://jila-pfc.colorado.edu/highlights/cross-cultural-spectroscopy (2016-04-29)
    Open archived version from archive

  • Chemistry in the Cosmos | JILA-PFC
    large molecules are produced during combustion and play a role in the formation of soot and ash Credit NASA ESA M Robberto Space Telescope Science Institute ESA and the Hubble Space Telescope Orion Treasury Project Team Searching for Clues in Quantum Fingerprints The Nesbitt group wants to figure out how chemistry works in outer space In particular the group wants to understand the cosmo chemistry leading to the generation of soot which is similar to products of combustion here on Earth Outer space is full of molecules Nesbitt explains We want to discover how these molecules are formed out there He adds that radio telescopes have gathered evidence of molecules made of long chains of carbon atoms Some of these molecules are quite unusual and consist of dozens of six carbon rings Nesbitt wants to know how interstellar clouds end up with what are essentially pieces of tar in them One clue has been the identification of ethynyl radical C 2 H in the Orion Nebula shown here and several other interstellar gas clouds Ethynyl radical is a reactive chemical produced when acetylene C 2 H 2 burns Almost as soon as a beaker of acetylene is lit centimeter long filaments made predominantly of carbon slowly rain down on the lab bench What is amazing is that molecules containing two carbon atoms are producing a super molecule with a million billion carbon atoms in about a millionth of a second The Nesbitt group thinks that ethynyl radical is key to understanding this transformation Once produced ethynyl radical almost instantly reacts with other carbon containing molecules to produce increasingly complex molecules resulting in soot and ash Since soot is also present in space the challenge for the Nesbitt group is to understand both cosmo chemistry and combustion as well as explain

    Original URL path: http://jila-pfc.colorado.edu/highlights/chemistry-cosmos (2016-04-29)
    Open archived version from archive

  • Ultracold Polar Molecules to the Rescue! | JILA-PFC
    technological breakthrough like this would drastically reduce world energy costs However this breakthrough requires a detailed understanding of the physics of high temperature superconductivity There is already a theoretical model called the t J model that contains the ingredients needed to explain the basic physics underlying high temperature superconductors containing copper and oxygen atoms Unfortunately because this model includes strong interactions of many electrons it s far too complex to solve with traditional analytical and computational methods Without details from the model it s impossible to determine the relationship of experimental observations to it Unfortunately theorists have been stymied in their efforts to improve their understanding of high temperature superconductivity until now A powerful collaboration between researchers at JILA CalTech and Harvard has come up with an elegant way to tackle the problem Research associates Salvatore Manmana and Gang Chen and Fellows Ana Maria Rey and Jun Ye worked with Alexey Gorshkov of CalTech and Eugene Demler and Mikhail Lukin of Harvard to propose and develop a novel quantum simulator The simulator uses a quantum gas of ultracold polar molecules of potassium rubidium KRb created by Fellows Deborah Jin and Jun Ye The ultracold molecules are polar because their electrons are unevenly distributed between the K and Rb atoms creating an electrical asymmetry that makes them susceptible to electric fields The KRb molecules are located in an optical lattice which forms the simulator Optical lattices are crystals of light formed by interacting laser beams They make it possible to exquisitely control the quantum motions of atoms or molecules inside the simulator The behavior of the ultracold molecules in the new simulator will likely model that of high temperature superconductivity in copper containing wires because the simulator uses external electric fields to ensure that the KRb molecules obey the same t

    Original URL path: http://jila-pfc.colorado.edu/highlights/ultracold-polar-molecules-rescue (2016-04-29)
    Open archived version from archive

  • The Cold Case | JILA-PFC
    between the classical world familiar to most people and the mysterious quantum world In this crossover region the interactions of two molecules are simple enough to be modeled quantum mechanically even though these interactions are far more complex than those between ultracold molecules at much lower temperatures The new quantum mechanical description of cold collisions was provided by the Ye group s theorist colleagues from Harvard and the University of Maryland This work helped the experimentalists investigate the crossover region where everything moves slowly enough to reveal new details about molecule collisions The group s investigations were made possible by the experimental setup shown in the figure This setup was designed by former graduate student Brian Sawyer graduate students Ben Stuhl and Mark Yeo research associates Matt Hummon and Yong Xia Fellow Jun Ye and colleagues from Harvard and the University of Maryland The researchers used the apparatus shown in the inset to slow and trap a beam of hydroxyl molecules OH at a temperature of 70 mK Then they propelled a beam of ammonia made with heavy hydrogen atoms ND 3 mixed with helium at 5 K through the bent tube above the trap A set of electrically charged rods guided only the ND 3 around a bend and onto the trap holding the OH molecules Once the ND 3 was flowing over the trapped OH the experimentalists studied cold collisions between them Because both OH and ND 3 are dipolar molecules they have an uneven internal distribution of electric charge resulting in one end being more positively charged and the other end being more negatively charged Cold dipoles exhibit interactions that are small compared to similar molecules at room temperature infrequent and until now hard to measure However with the new setup the Ye group was able to

    Original URL path: http://jila-pfc.colorado.edu/highlights/cold-case (2016-04-29)
    Open archived version from archive

  • Probing the Tell-Tale Ions | JILA-PFC
    huge internal electric field in response to a much smaller field applied to it in the laboratory A small electric field applied in the laboratory to an ensemble of trapped HfF ions would precisely align all the internal electric fields of the ions making it possible for researchers to test for an eEDM in an unpaired electron located near the Hf atom as shown in the drawing But before the scientists can attempt to identify an eEDM signal they must understand the electronic structure of HfF That s they only way they can identify which tree in a whole forest of normal transitions in the ion is most suitable for observing the coveted eEDM signal Unfortunately researchers have only recently become interested in HfF and there is as yet little experimental data on its electronic structure Even theoretical models have large uncertainties This situation is about to change however thanks to graduate students Laura Sinclair and Kevin Cossel undergraduate Tyler Coffey and Fellows Jun Ye and Eric Cornell Sinclair and her colleagues recently invented an ultrahigh sensitivity high resolution technique called frequency comb velocity modulation spectroscopy that will make it possible to rapidly identify and characterize the electronic structure of HfF In a nutshell the new technique shakes up a mixture of HfF ions and HfF molecules Shaking modulates just the signals coming from the ions The researchers then hone in on the modulated signals by looking for either increases or decreases in frequency It s like pinpointing the location of an ambulance running with a siren by analyzing whether the sound you hear is getting louder and higher pitched as it comes closer to you or softer and lower pitched as it moves away from you This powerful and efficient new technique allows the researchers to rapidly look for

    Original URL path: http://jila-pfc.colorado.edu/highlights/probing-tell-tale-ions (2016-04-29)
    Open archived version from archive