The MIT DEPARTMENT OF PHYSICS presents

The 17th Annual Pappalardo Fellowships
in Physics Symposium

THURSDAY, MAY 17, 2018

2:00 - 5:00 PM


MIT Department of Physics
Pappalardo Community Room
Building 4, Room 349
Cambridge, MA

Five members of the Department's premier postdoctoral fellowship program, the Pappalardo Fellowships in Physics, will present highlights from their independent research projects.The talks are designed for the enjoyment of all members of the MIT physics community.

Refreshments available for attendees in the foyer of 4-349 beginning at 1:30 pm.

 

SCHEDULE OF SPEAKERS

  TIME SPEAKER TITLE & ABSTRACT
  1:45 pm   Refreshments for attendees served in foyer outside the Pappalardo Community Room
(4-349).
2:00 pm

Pablo Jarillo-Herrero, Professor of Physics

Introductory Remarks
2:15 pm

Julieta Gruszko,
2017-2020 Fellow
(Experimental Nuclear & Particle Physics)

Shedding “Nu” Light on the Nature of Matter

Why is the universe dominated by matter, and not antimatter? This is a basic and fundamental question, but we cannot yet answer it. Neutrinos, which are elusive neutral particles with tiny masses, could give us insight into this and other outstanding questions in fundamental physics. If the neutrino is its own antiparticle, processes that create particles with no corresponding anti-particles would then be possible, giving us a new path forward to explain the predominance of matter over anti-matter in our universe. To discover whether this is the case, we must search for neutrinoless double-beta decay, a theorized process that would occur in some nuclei.

Detecting this extremely rare process, however, requires us to build multi-ton detectors with very low background rates. At MIT, we’re beginning construction on NuDot, a proof-of-concept experiment that will explore promising techniques for future detectors. I’ll discuss the progress we’ve already made in demonstrating how previously-ignored light signals can help us distinguish signal from background, and the technologies we’re developing with an eye towards the coming generations of experiments.

  2:30 pm Question & Answer
2:45 pm

Zhen Bi,
2017-2020 Fellow
(Theoretical Condensed Matter Physics)

The Universe in Topological Phases

Condensed matter physics studies phases of matter and the transitions between them. Symmetry has been a powerful and successful mathematical principle to differentiate phases of matter. For example, crystalline solids can be classified by the symmetry of their atomic arrangement pattern. However, symmetry is not the whole story. Nature provides us with many new exotic phases of matter, such as Integer and Fractional Quantum Hall Effects, where topology emerges as a natural mathematical language to capture the physics.

In this talk, I will discuss some recent progress on understanding topological phases of matter. There are a vast set of new quantum phases—named symmetry-protected topological phases—once we take into account the interplay between symmetry and topology. I will also talk about our recent work on phase transitions between topological phases. We found that non-abelian gauge fields (the mediator of the weak and strong forces between elementary particles in our universe) naturally emerge at some topological phase transition.

  3:00 pm   Question & Answer
3:15 pm

Michael Wagman,
2017-2020 Fellow
(Theoretical Nuclear & Particle Physics)

Nuclei, Neutrinos, and New Physics

Neutrino oscillations provide direct experimental evidence for beyond-the-Standard Model physics. Experimental searches for neutrinoless double-beta decay can test new physics theories predicting non-zero neutrino masses and neutrino oscillations. Double-beta decay searches and other neutrino experiments measure nuclear reaction rates, and nuclear theory is needed to relate these reaction rates to the underlying parameters of the Standard Model and its possible extensions.

I will discuss my research on lattice field theory simulations of nuclear physics from the Standard Model, including proton-proton fusion and double-beta decay in a small nucleus. Lattice simulations involving larger nuclei relevant to double-beta decay experiments face exponentially hard signal-to-noise problems related to phase fluctuations, and I will also mention my ongoing research at MIT to apply “phase unwrapping” techniques to improve signal-to-noise in lattice field theory simulations.

  3:30 pm Question & Answer
3:45 pm I N T E R M I S S I O N
4:00 pm

Lampros Lamprou,
2017-2020 Fellow
(String Theory)

Spacetime from Quantum Mechanics

Black holes reveal a deep inconsistency between our two experimentally successful physical frameworks: Quantum Mechanics and General Relativity. Quantum theory endows black holes with the ability to irreversibly destroy information via their evaporation—a fact contradicting the very principles of quantum mechanics. This is the famous information paradox, whose resolution has been traditionally described as the program of "Quantization of Gravity."

In this talk, I will suggest the idea that the answer lies, instead, in the converse: the "Geometrization of Quantum Mechanics." This novel perspective leads to the surprising insight that Einstein's spacetime is an emergent concept, with its dynamical geometry providing an approximate description of an underlying quantum theory. 

How do we get spacetime from quantum mechanics? What properties of the quantum system can probe the curvature of spacetime, which is responsible for the gravitational force according to general relativity? I will present a simple idea for how to approach this question, which I've proposed in my most recent work, and which will be the subject of my ongoing research.

  4:15 pm Question & Answer
4:30 pm

Itamar Kimchi,
2015-2018 Fellow,
(Theoretical Condensed Matter Physics)

Dirty Quantum Entanglement

Recent developments in quantum condensed matter theory provide us with a better understanding of possible behavior that can arise when many electrons interact. This understanding is often based on idealized theoretical settings that can only sometimes be applicable to the electrons in a piece of material such as a magnetic insulator. One intriguing question is how to create and observe an entangled state of two electrons, with its "spooky action at a distance," for a pair of electrons separated across distant atoms. 

I will present our new theoretical work that answers this question by addressing a difficult but important ingredient: randomness, that necessarily arises in real materials. I will show, with pictures, how randomness can stabilize long-range entanglement. Finally, I'll show strong evidence that our theory indeed describes many real quantum magnetic materials.

  4:45 pm Question & Answer
5:00 pm F I N I S

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