Insights from quantum information theory show that correlation measures based on quantum entropy are fundamental tools that reveal the entanglement structure of multipartite states. In that spirit, Groisman, Popescu, and Winter [Phys. Rev. A 72, 032317 (2005)] showed that the quantum mutual information I ( A ; B ) quantifies the minimal rate of noise needed to erase the correlations in a bipartite state of quantum systems A B . Here, we investigate correlations in tripartite systems A B E . In particular, we are interested in the minimal rate of noise needed to apply to the systems A E in order to erase the correlations between A and B given the information in system E , in such a way that there is only negligible disturbance on the marginal B E . We present two such models of conditional decoupling, called deconstruction and conditional erasure cost of tripartite states A B E . Our main result is that both are equal to the conditional quantum mutual information I ( A ; B | E ) —establishing it as an operational measure for tripartite quantum correlations.
On Friday, August 3, LSU Physics & Astronomy welcomed three new PhD graduates who were awarded their degrees at the Marvavich Assembly Center. They are John Chapman, Jonathan Cripe, and Joseph Steiner
Meet Elizabeth Hilliard, a medical physics graduate from the LSU Department of Physics and Astronomy, whose M.S. project was working to improve the efficiency and control of electron beam exposure in cancer patients needing radiation therapy. Elizabeth has undergraduate degrees in both physics and psychology from Rensselaer Polytechnic Institute. She recently won the LSU Three Minute Thesis (#3MT) competition by presenting a winning story about her research on stage for the LSU Graduate School, and moved on to compete in the regional 3MT competition in Fayetteville, AR.
The wavefunction Monte-Carlo method, also referred to as the use of 'quantum jump trajectories', allows efficient simulation of open systems by independently tracking the evolution of many pure-state 'trajectories'. This method is ideally suited to simulation by modern, highly parallel computers. Here we show that Krotov's method of numerical optimal control, unlike others, can be modified in a simple way so that it becomes fully parallel in the pure states without losing its effectiveness. This provides a highly efficient method for finding optimal control protocols for open quantum systems and networks. We apply this method to the problem of generating entangled states in a network consisting of systems coupled in a unidirectional chain. We show that due to the existence of a dark state subspace in the network, nearly optimal control protocols can be found for this problem by using only a single pure-state trajectory in the optimization, further increasing the efficiency.
LSU physicist among the two dozen researchers funded
Extended results on the cosmic-ray electron + positron spectrum from 11 GeV to 4.8 TeV are presented based on observations with the Calorimetric Electron Telescope (CALET) on the International Space Station utilizing the data up to November 2017. The analysis uses the full detector acceptance at high energies, approximately doubling the statistics compared to the previous result. CALET is an all- calorimetric instrument with a total thickness of 30 radiation lengths at normal incidence and fine imaging capability, designed to achieve large proton rejection and excellent energy resolution well into the TeV energy region. The observed energy spectrum in the region below 1 TeV shows good agreement with Alpha Magnetic Spectrometer (AMS-02) data. In the energy region below ∼300 GeV, CALET’s spectral index is found to be consistent with the AMS-02, Fermi Large Area Telescope (Fermi-LAT), and Dark Matter Particle Explorer (DAMPE), while from 300 to 600 GeV the spectrum is significantly softer than the spectra from the latter two experiments. The absolute flux of CALET is consistent with other experiments at around a few tens of GeV. However, it is lower than those of DAMPE and Fermi-LAT with the difference increasing up to several hundred GeV. The observed energy spectrum above ∼1 TeV suggests a flux suppression consistent within the errors with the results of DAMPE, while CALET does not observe any significant evidence for a narrow spectral feature in the energy region around 1.4 TeV. Our measured all-electron flux, including statistical errors and a detailed breakdown of the systematic errors, is tabulated in the Supplemental Material in order to allow more refined spectral analyses based on our data.
We present the detection of a blackbody component in GRB 160107A emission by using the combined spectral data of the CALET Gamma-ray Burst Monitor (CGBM) and the MAXI Gas Slit Camera (GSC). The MAXI/GSC detected the emission ∼45 s prior to the main burst episode observed by the CGBM. The MAXI/GSC and the CGBM spectrum of this prior emission period is well fit by a blackbody with the temperature of 1.0+0.3−0.2 keV plus a power-law with the photon index of −1.6±0.3. We discuss the radius to the photospheric emission and the main burst emission based on the observational properties. We stress the importance of the coordinated observations via various instruments collecting the high quality data over a broad energy coverage in order to understand the GRB prompt emission mechanism.
The Laser Interferometer Gravitational Wave Observatory, or LIGO, in Livingston, La., will be designated a historic physics site by the American Physical Society, or APS, on Wednesday, June 20. Media are invited to attend this special ceremony beginning at 11 a.m. To RSVP, email the media relations contacts below. LIGO Livingston is one of two observatories in the U.S. that made the first direct observations of gravitational waves emanating from violent and distant astronomical events. The two observatories — one in Louisiana and the other in Hanford, Wash. — will receive plaques to recognize the extraordinary efforts that led to this detection.
Dr. Rick Rauch (Science, ’77), an expert in rocket propulsion testing, will provide a $1 million bequest to establish an endowed research scholarship fund for the LSU Department of Physics & Astronomy. A product of the 1960s, Rauch is living his childhood dream as project manager at NASA’s John C. Stennis Space Center.
2016 LSU graduate, Mark DiTusa, is the recipient of the 2018 National Science Foundation Graduate Research Fellowship Program, or GRFP. This fellowship from the National Science Foundation helps ensure the vitality of the human resource base of science and engineering in the U.S. and reinforces its diversity. DiTusa is currently pursuing his Ph.D. at the University of Chicago.
In the literature on the continuous-variable bosonic teleportation protocol, it is often loosely stated that it converges to a perfect teleportation of an input quantum state in the limit of ideal squeezing and ideal detection, but the exact form of this convergence is typically not clarified. In this work, Prof. Wilde explicitly clarifies that the convergence is in the strong sense, and not the uniform sense, and furthermore that the convergence occurs for any input state to the protocol, including the infinite-energy Basel states defined and discussed in this work. Prof. Wilde also proves, in contrast to the above result, that the teleportation simulations of pure-loss, thermal, pure-amplifier, amplifier, and additive-noise channels converge both strongly and uniformly to the original channels, in the limit of ideal squeezing and detection for the simulations. For these channels, he gives explicit uniform bounds on the accuracy of their teleportation simulations. These uniform convergence results are then extended to particular multimode bosonic Gaussian channels. These convergence statements have important implications for mathematical proofs that make use of the teleportation simulation of bosonic Gaussian channels, some of which have to do with bounding their nonasymptotic secret-key-agreement capacities.
A team of high school students will present new findings on KIC 8462852, or Tabby’s Star, often referred to as the most mysterious star in the universe, at a press conference at the American Astronomical Society meeting in Denver, Colo. today. Tabby’s Star is nicknamed after LSU Department of Physics & Astronomy Assistant Professor Tabetha Boyajian, who has observed and studied the unusual dimming and brightening of this otherwise ordinary star along with citizen scientists.
The Montevideo interpretation of quantum mechanics, which consists of supplementing environmental decoherence with fundamental limitations in measurement stemming from gravity, has been described in several publications. However, some of them appeared before the full picture provided by the interpretation was developed. As such, it can be difficult to get a good understanding via the published literature. Here, we summarize it in a self-contained brief presentation including all its principal elements
BATON ROUGE - LSU Professor Jonathan P. Dowling has been appointed to a three-year term as Distinguished Visiting Professor of the Chinese Academy of Sciences. Dowling is the Horace C. Hearne Professor of Theoretical Physics and founding Co-Director of the Horace C. Hearne Institute for Theoretical Physics in the LSU College of Science. The Institute carries out research on quantization of gravity, quantum optics effects in gravitational wave interferometers, decoherence due to quantum gravity, non-standard optics due to quantum gravity, quantum computing, quantum imaging, and quantum sensing.
On Friday, May 11, LSU Physics & Astronomy welcomed 3 new PhD, 2 MS and 14 BS graduates who received their diplomas at the Pete Maravich Assembly Center and Maddox Fieldhouse.
2018 University Distinguished Faculty Awards and Annual Physics & Astronomy Awards
LSU's Department of Physics & Astronomy has announced Rebecca DiTusa and Khang Pham as recipients of the NRC scholarship program in health physics. A grant from the U.S. Nuclear Regulatory Commission (NRC) was established at LSU in 2017 supporting undergraduate students to explore careers in the radiation sciences through the field of health physics.
Rainer Weiss, 2017 Nobel Laureate in Physics, MIT Physics Professor Emeritus, and LSU adjunct professor in physics and astronomy, will serve as the keynote speaker for the LSU College of Science spring ceremony, Friday, May 11 at 12 p.m. in Maddox Field House.
2018 Annual Physics & Astronomy Awards list and gallery
Emeritus Boyd Professor Dr. Robert O'Connell is originally from Ireland and received his undergraduate degree from the National University of Ireland Galway, which also awarded him a doctorate of science degree later on. After working four years as a telecommunications engineer, he came to the US in 1958 and got his Ph.D. in theoretical physics from the University of Notre Dame. In his 53-year career at LSU, Dr. O'Connell has made countless contributions to many areas of physics and astronomy.
For more than 30 years, the Astronaut Scholarship Foundation has supported hundreds of top performing students pursuing degrees in science, technology, engineering or mathematics. This year, LSU physics majors Rory Bentley and Harvey Shows are among the top performing scholars to receive the ASF award.
Dowling and collaborators have been awarded more than $7 million from the U.S. Army Research Office to develop quantum technologies related to sensing. Their recently received grant titled, “Quantum control based on real-time environment analysis by spectator qubits,” is funded for three years, with the possibility of a two-year extension for a total of $7.05 million. The purpose of the grant is to develop feedback and control techniques on quantum systems that will be used to improve the performance of quantum computers and sensors.
We present a theoretical investigation of charge migration following strong-field ionization in a multielectron system. We study a model homonuclear molecule with two electrons, each restricted to one dimension ( 1 + 1 D ), interacting with a strong, static electric field. We show that in this system charge migration results from the interplay between multiple ionization channels that overlap in space, creating a coherent electron-hole wave packet in the cation. We also find that, in our case, charge migration following the first ionization manifests as a modulation of the subsequent double-ionization signal. We derive a parametrized semiclassical model from the full multielectron system and we discuss the importance of the choice of cation electronic-structure basis for the efficacy of the semiclassical representation. We use the ab initio solution of the full 1 + 1 D system as a reference for the qualitative and quantitative results of the parametrized semiclassical model. We discuss the extension of our model to long-wavelength time-dependent fields with full-dimension, many-electron targets.
We extend the phenomenology of loop quantum cosmology (LQC) to second order in perturbations. Our motivation is twofold. On the one hand, since LQC predicts a cosmic bounce that takes place at the Planck scale, the second order contributions could be large enough to jeopardize the validity of the perturbative expansion on which previous results rest. On the other hand, the upper bounds on primordial non-Gaussianity obtained by the Planck Collaboration are expected to play a significant role on explorations of the LQC phenomenology. We find that the bounce in LQC produces an enhancement of non Gaussianity of several orders of magnitude, on length scales that were larger than the curvature radius at the bounce. Nonetheless, we find that one can still rely on the perturbative expansion to make predictions about primordial perturbations. We discuss the consequences of our results for LQC and its predictions for the cosmic microwave background.
Taddei PJ, Khater N, Youssef B, Howell RM, Jalbout W, Zhang R, Geara FB, Giebeler A, Mahajan A, Mirkovic D, Newhauser WD. Low- and middle-income countries can reduce risks of subsequent neoplasms by referring pediatric craniospinal cases to centralized proton treatment centers. Biomed. Phys. Eng. Express. 4 025029 (2018).
LSU College of Science and Roger Hadfield Ogden Honors College sophomore Corey Matyas has been named a 2018 Goldwater Scholar. Matyas, a native of Dahlonega, Ga., was nominated through an internal university process earlier in the year. A list of winners was released on Friday, March 30.
The 2018 SEC Faculty Achievement Award selection from LSU is Ward Plummer, Boyd Professor of Physics. Plummer is special assistant to LSU’s vice president for research and economic development. He is a world‐renowned physicist, specializing in surfaces and interfaces phenomena
Physics undergraduate Khang Pham, a native of Vietnam, and a McNair Research Scholar, has been named a 2018 LSU Discover Scholar awardee. Currently mentored by Professor Catherine Deibel, Pham is doing research in the nuclear physics group.
The CALorimetric Electron Telescope (CALET), launched for installation on the International Space Station (ISS) in August, 2015, has been accumulating scientific data since October, 2015. CALET is intended to perform long-duration observations of high-energy cosmic rays onboard the ISS. CALET directly measures the cosmic-ray electron spectrum in the energy range of 1 GeV to 20 TeV with a 2% energy resolution above 30 GeV. In addition, the instrument can measure the spectrum of gamma rays well into the TeV range, and the spectra of protons and nuclei up to a PeV.
The International Conference on Quantum Communication, Measurement and Computing (QCMC), established in 1990 to encourage and bring together scientists and engineers working in the interdisciplinary field of quantum information science and technology, will take place March 12-16, 2018 at Louisiana State University. Organized by the LSU Quantum Science and Technologies Group (QST), the 2018 QCMC conference will highlight research areas on nano photonic quantum information and processing.
The Southeastern Universities Research Association, or SURA, announced that Gabriela González, professor of physics and astronomy at LSU and former spokesperson of the LIGO Scientific Collaboration, will receive the 2018 SURA Distinguished Scientist Award. The annual honor goes to a research scientist whose extraordinary work fulfills the SURA mission to “advance collaborative research and education” in the Southeast and nation.
LSU Professor Josef Hormes will conduct this cutting-edge research on samples of prehistoric artifacts from Poverty Point at the LSU J. Bennett Johnston, Sr., Center for Advanced Microstructures and Devices, or CAMD, with support from the National Park Service.
The LSU Chapter of the Society of Physics Students (SPS) received the 2016-2017 Distinguished Chapter Award from the national office of the SPS within the American Institute of Physics. SPS is an organization for students interested in the fields of physics and astronomy. Their primary purpose is to promote the appreciation and advancement of physics and astronomy in the community, as well as to further educate members in these fields. The LSU SPS group participates in multiple outreach events throughout the year, including Mini Maker Faire, NanoDays, International Astronomy Day, Earth Day, LASM Engineering Day, in addition to visits to middle and high schools for science fairs and similar events.
Mengxi Wu, Yongsing You, Shambhu Ghimire, David A. Reis, Dana A. Browne, Kenneth J. Schafer, and Mette B. Gaarde Phys. Rev. A 96, 063412 – Published 18 December 2017
Author: Seth Camp, Samuel Beaulieu, Kenneth J Schafer and Mette B Gaarde Published 21 February 2018 • © 2018 IOP Publishing Ltd Journal of Physics B: Atomic, Molecular and Optical Physics, Volume 51, Number 6
Siddhartha Das, George Siopsis, and Christian Weedbrook Phys. Rev. A 97, 022315 – Published 12 February 2018
If anyone is a life-long learner, it's LSU Physics alumna Leslie Austin. Leslie is from Baton Rouge and always wanted to be a Tiger. After earning her B.S. in Physics in 2000, she worked for a year as a research associate for the Department of Physics & Astronomy, traveling to Antarctica as part of the Advanced Thin Ionization Calorimeter (ATIC) project. She later went to law school at the LSU Paul M. Hebert Law Center, and then began a career in human resources (HR) with a focus on labor and employment law compliance. "I thought about obtaining an MBA, but chose law school because I was always interested in the legal system, I minored in English, and I thought patent law might be a good fit with science backgrounds." Today, she is Chief Operating Officer for HR Solutions.
For the ninth consecutive year, LSU will host NanoDays at the Highland Road Park Observatory, or HRPO, on Saturday, Feb. 24, from 2-6 p.m. followed by a presentation by David Young, a professor in the LSU Department of Physics & Astronomy, “Alternative Energy! Using nanotechnology to improve the performance of thermoelectric materials,” at 6:15 p.m.
Margarite, a native of the Baton Rouge area, is passionate about physics research. She participated in the National Institute of Standards and Technology (NIST) Summer Undergraduate Research Fellowship (SURF) program and recently presented some of her research "Multiparameter Estimation with Single Photons" at the Japan Society of Applied Physics-Optical Society of America joint symposia in Fukuoka, Japan thanks in part to the LSU Discover Travel Stipend!
China’s President Jinping Xi presented the 2017 International Science and Technology Cooperation Award of the People’s Republic of China to Professor Earl Ward Plummer, a faculty member in the LSU Department of Physics & Astronomy. Plummer was one of seven people to receive this award for his contribution to the development of science and technology in China.
A revolutionary material harbors magnetism and massless electrons that travel near the speed of light—for future ultrasensitive, high-efficiency electronics and sensors.
The Planet Hunters citizen science project announced the serendipitous discovery of KIC 8462852, a peculiar variable star observed by the NASA Kepler mission (Borucki et al. 2010) from 2009 to 2013 (Boyajian et al. 2016). KIC 8462852’s variability manifests itself as asymmetric drops in brightness of up to 22%, many of which last several days (the “dips”). There is little or no sign of periodicity in the four years of Kepler observations (but see Kiefer et al. 2017). Additionally, the duty cycle of the dips is low, occurring for less than 5% of the four-year period Kepler observed it. Subsequent ground-based follow-up observations to better characterize the star revealed nothing other than KIC 8462852 being an ordinary, main-sequence F3 star: no peculiar spectral lines, Doppler shifts indicative of orbiting companions, or signs of youth such as an infrared excess (Lisse et al. 2015; Marengo et al. 2015; Boyajian et al. 2016; Thompson et al. 2016).
We report ground-based spectrophotometry of KIC 8462852, during its first dimming events since the end of the Kepler mission. The dimmings show a clear colour-signature, and are deeper in visual blue wavelengths than in red ones. The flux loss' wavelength dependency can be described with an \AA ngstr\"om absorption coefficient of 2.19±0.45, which is compatible with absorption by optically thin dust with particle sizes on the order of 0.0015 to 0.15 μm. These particles would be smaller than is required to be resistant against blow-out by radiation pressure when close to the star. During occultation events, these particles must be replenished on time-scales of days. If dust is indeed the source of KIC 8462852's dimming events, deeper dimming events should show more neutral colours, as is expected from optically thick absorbers.
A team of more than 100 researchers, led by LSU Department of Physics & Astronomy Assistant Professor Tabetha Boyajian, is one step closer to solving the mystery behind the “most mysterious star in the universe.” KIC 8462852, or “Tabby’s Star,” nicknamed after Boyajian, is otherwise an average star. It is about 50 percent bigger and 1,000 degrees hotter than the Sun. It is more than 1,000 light years away. However, it has been inexplicably dimming and brightening sporadically like no other. Several theories abound to explain the star’s unusual light patterns including an alien megastructure orbiting the star.
Robert F. O'Connell, PhD, LSU Boyd professor, has retired after a distinguished career as a researcher, administrator and mentor. He joined the faculty of the LSU Department of Physics & Astronomy in January 1964 as a tenure-track assistant professor.
A long term program of photoelectric UBVRI photometry has been combined with AAVSO archival data for the hot, R CrB-type hydrogen deficient star MV Sgr. A deep minimum and a trend of decreasing brightness over time at maximum light thereby become evident. Variations seen via monitoring with a CCD detector also are described.
Colleen Fava, program manager of the Louisiana Space Grant Consortium (LaSPACE) / NASA EPSCoR, has been announced as one of the recipients of the 2017 LSU Foundation Staff Outstanding Service Awards. This annual award was established to recognize the superior work performance and outstanding contributions of full-time, non-academic staff employees of the LSU A&M campus and the LSU AgCenter.
This research showed the dramatic dependence of the magnetic state on the size of the crystal lattice and points out the opportunity for exploring the origins of anti-symmetric interactions through a combination of experiment, neutron scattering, and electronic structure calculation.
On Friday December 8, 2017, LSU Board of Supervisors awarded Professor Ward Plummer the rank of Boyd Professor. The Boyd Professorship is the highest professorial rank awarded by the LSU System and is given only to professors who have attained national or international distinction for outstanding teaching and research. Plummer is the 75th Boyd Professor named across LSU, and the 49th from the Flagship campus to be awarded the coveted title since it was established in 1953 to honor brothers David and Thomas Boyd, early faculty members and presidents of LSU. With this appointment, there are now 11 active Boyd Professors at the Flagship University.
On Friday, December 15, LSU Physics & Astronomy welcomed 3 new PhD, 3 MS and 2 BS graduates who conferred their degrees at the Maddox Fieldhouse.