Events at Physics |
Events During the Week of January 25th through February 1st, 2015
Monday, January 26th, 2015
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Current redistribution and transport in the RFP
- Time: 12:00 pm - 1:00 pm
- Place: 1610 Engineering Hall
- Speaker: Dr. Eli Parke, UW- Madison
- R. G. Herb Condensed Matter Seminar
- Faculty Candidate Seminar
- From Quantum Communications to Small Quantum Computers
- Time: 4:00 pm - 5:00 pm
- Place: 4274 Chamberlin Hall
- Speaker: Graeme Smith, IBM TJ Watson Research Center
- Abstract: Physical information carriers obey quantum laws. Taking proper account of this fact has led over the past few decades to profound generalizations of both communication and computation theory. First, I’ll discuss the central question in the theory of quantum communication: What are the capabilities of a noisy quantum communication link? Addressing this question leads us to concepts like entanglement, a fundamentally quantum form of correlations which turns out to be a remarkably useful resource, new capabilities such as unconditionally secure cryptographic key agreement, and classically impossible kinds of synergy between independent communication links. Second, I’ll discuss two key questions in the race to build a quantum computer: what can we do with a small quantum computer, and how can we know that we’ve done it? These will be central questions in the coming decade as the size of quantum computing experiments begins to outstrip our capacity to do effective modeling on classical machines.
- Host: Coppersmith
Tuesday, January 27th, 2015
- Chaos & Complex Systems Seminar
- Madison Science Museum: from chaos to complexity
- Time: 12:05 pm - 1:00 pm
- Place: 4274 Chamberlin Hall (Refreshments will be served)
- Speaker: Olga Trubetskoy and Dave Nelson, Madison Science Museum
- Abstract: We will start from ongoing story of starting up a science museum in Madison describing how from initial turmoil, obstacles and defeats the museum is now emerging being shaped by inspiration, visions and public involvement. We will resume the saga by revealing a few curious stories from Madison science history scene that will be a part of a future museum exhibits.
- Host: Clint Sprott
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Faculty Candidate Seminar
- Chasing our Cosmic Dawn: Opening the 21cm cosmological window on the universe
- Time: 2:00 pm - 3:00 pm
- Place: 4274 Chamberlin Hall
- Speaker: Daniel C. Jacobs, NSF Fellow, Arizona State University
- Abstract: The Epoch of Reionization (EoR) marks when the first stars ionized primordial hydrogen half a billion years after the big bang. Direct observation of cosmological hydrogen is possible via the 21cm line and is now being hotly pursued as a new cosmological probe. I am a major contributor to new large-scale radio arrays including the Precision Array for Probing the Epoch of Reionization (PAPER), the Murchison Widefield Array (MWA) and the upcoming Hydrogen Epoch of Reionization Array (HERA). PAPER currently holds the deepest limits on the epoch of reionization power spectrum, while the MWA is making major advancements in understanding foregrounds at a level necessary for imaging large scale structure. My group specializes in commissioning, operating and delivering results with these new types of arrays. Current projects include digital modeling of instrumental response, developing high level heuristics for data flagging, accelerating imaging pipelines, pushing more analysis steps into real-time systems, and in-situ calibration with external drone-mounted transmitters. Lessons learned and systems developed for PAPER and the MWA are being incorporated into the design and operations model of the next generation HERA, which will yield 20 times the sensitivity of first generation arrays and on into the regime of the upcoming Square Kilometer Array.
- Host: Dasu
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Faculty Candidate Seminar
- One century of neutrino mass experiments: from radium salts to microwaves
- Time: 4:00 pm - 5:00 pm
- Place: 4274 Chamberlin Hall
- Speaker: Benjamin Monreal, UCSB
- Abstract: The neutrino mass is one of the longest-standing unanswered questions in physics. We've recently learned a tremendous amount about how the weak interaction mixes neutrino mass states together; we've learned that there are three different, and we've narrowed the ordering of these masses down to two; but we still haven't learned what the masses actually are. The KATRIN experiment, soon to start data taking, will use a huge electrostatic spectrometer to search for the signature of a massive neutrino in beta decay, but astrophysicists predict that the mass scale is too small for KATRIN to see. Project 8's microwave spectrometry technique may provide the next, crucial, factor of 10 in this search; I will present recent Project 8 data showing our single-electron detection, tracking, and spectroscopy capabilities.
- Host: Dasu
Wednesday, January 28th, 2015
- R. G. Herb Condensed Matter Seminar
- Faculty Candidate Seminar
- Quantum control of atoms, ions, and nuclei
- Time: 4:00 pm - 5:00 pm
- Place: 4274 Chamberlin Hall
- Speaker: Christian Schneider, UCLA
- Abstract: Cold atoms and ions provide an interesting playground for a
variety of measurements of fundamental physics. Using RF traps, experiments
become possible with both large ensembles of ions, e.g. in cold chemistry, and
few/single ions, such as in quantum computations/simulations or optical clocks,
where ultimate quantum control is required. In the first part of the talk,
recent results from our work on cold chemistry and cold molecular ions using a
hybrid atom--ion experiment will be presented. We have developed an integrated
time-of-flight mass spectrometer, which allows for the analysis of the complete
ion ensemble with isotopic resolution. Using this new setup, we have
significantly enhanced previous studies of cold reactions in our
system. Potential routes towards ultra-cold reactions at the quantum level
will be presented. Current work aims at demonstrating rotational cooling of
molecular ions and photo-associating molecular ions.
The second part of the talk reports on our results of the search for the
low-energy isomeric transition in thorium-229. This transition in the
vacuum-ultraviolet regime (around 7.8 eV) has a lifetime of tens of
minutes to several hours and is better isolated from the environment
than electronic transitions. This makes it a very promising
candidate for future precision experiments, such as a nuclear clock or tests of
variation of fundamental constants, which could outperform implementations
based on electronic transitions. Our approach of a direct search for the
nuclear transition uses thorium-doped crystals and, in a first experiment,
synchrotron radiation (ALS, LBNL) to drive this transition. We were able to
exclude a large region of possible transition frequencies and lifetimes.
Currently, we continue our efforts with enhanced sensitivity using a pulsed VUV
laser system.
- Host: Coppersmith
Thursday, January 29th, 2015
- Atomic Physics Seminar
- Observation of ultracold Cs Rydberg molecules with kiloDebye dipole moments
- Time: 2:00 pm
- Place: 5310 Chamberlin
- Speaker: Donald Booth, University of Oklahoma
- Abstract: We present results on our Cs ultracold Rydberg atom experiments involv-<br>
ing two classes of ultralong-range Rydberg molecules known as trilobite" and<br>
butter<br>
y" molecules. These molecules are predicted to have giant, body- xed<br>
permanent dipole moments on the order of 1000 Debye. The two classes of<br>
molecules are distinguished by the relative dominance of the s-wave and p-wave<br>
electron scattering. We present spectra for (nS1=2 +6S1=2)3 molecules, where<br>
n = 37, 39 and 40, and measurements of the Stark broadenings of selected<br>
trilobite states in Cs due to the application of a constant external electric eld.<br>
Additionally, we present measurements of spectra and Stark splittings for p-<br>
wave dominated (nS1=2 + 6S1=2)3 molecules, where n = 31 and 32.<br>
- Host: Saffman
- Astronomy Colloquium
- Puzzles in Massive Galaxy Assembly
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall
- Speaker: Nicholas McConnell, Ifa, University of Hawaii
- Abstract: Do giant elliptical galaxies represent the final outcome of a common sequence of galaxy growth and merging, or are they the relics of exceptional objects that formed violently in the early universe? I will describe observational efforts to understand two features of the most massive ellipticals: their stellar populations and their supermassive black holes. (1) The Black Hole Safari is a campaign to measure stellar kinematics and central black hole masses (MBH) in over 30 giant elliptical
galaxies, spanning a range of cosmic environments. The resulting census of black holes in the local universe will assess whether the linear relation between MBH and stellar spheroid mass arises naturally from hierarchical merging, and it may shed light upon the origins of recently-discovered overmassive black holes. (2) The most massive elliptical galaxies exhibit an extremely bottom-heavy stellar initial mass function (IMF), at odds with
galaxy formation models where they are assembled from mergers of lower-mass systems. One possible means of reconciliation would be the detection of radial gradients in the IMF. I will present new measurements of IMF-sensitive spectral features with unprecedented radial coverage, suggesting that massive ellipticals' extreme are indeed confined to small radii. - Host: Prof Tremonti
- R. G. Herb Condensed Matter Seminar
- Faculty Candidate Seminar
- Noise in superconducting circuits: microscopic theory and open questions
- Time: 4:00 pm - 5:00 pm
- Place: 4274 Chamberlin
- Speaker: Lara Faoro, Laboratoire de Physique Theorique et Hautes Energies
- Abstract: I review the main sources of noise in superconducting circuits: charge noise, critical current noise, quasiparticle poisoning and flux noise. I discuss the microscopic mechanism for these noises and show that charge and critical current noise are accounted for by the microscopic model that assumes the presence of localized electron states at the Superconductor Insulator interfaces. Due to the large electron electron interaction these states form resonances close to the Fermi surface. These states serve as traps where the quasiparticles live for a long time. The spins of the quasiparticles in these states produce flux noise of the right magnitude and frequency dependence. However the correlation between the magnetization and susceptibility noise observed by R. McDermott remains unexplained.
- Host: Coppersmith
Friday, January 30th, 2015
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:15 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
http://cmb.physics.wisc.edu/journal/index.html
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Le Zhang (lzhang263@wisc.edu) - Host: Peter Timbie
- Theory Seminar (High Energy/Cosmology)
- Hunting for Hierarchies in PSL2(7)
- Time: 3:00 pm - 4:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Michael Jay Perez, University of Florida
- Abstract: I will give a review of recent work done in collaboration with G. Chen and P. Ramond (arXiv 1412.6107). Attention is drawn to a finely tuned Seesaw Majorana matrix linked to the charge 2/3 quarks hierarchy. With a diagonal Dirac neutrino matrix, it gives tribimaximal mixing, and a normal hierarchy for the light neutrinos. We present a model with the family group PSL2(7) where this Majorana matrix is natural, and the top quark hierarchy, determined by the vacuum values of familon fields, is transferred to Higgs fields with family quantum numbers. PSL2(7)-invariant couplings then produce a μ-term at a scale commensurate with neutrino and quark masses, and a hierarchy of thirteen orders of magnitude. This results in only one Higgs field (per hypercharge sector) with a μ-mass ∼10−100 GeV. With SUSY soft breaking, its vacuum value is automatically aligned to give masses to the top and bottom quarks.
- Host: Lisa Everett