Fall 2024 Schedule
Fall 2024 Colloquia will be held in Room 307 of the Science and Engineering Research Facility on Mondays at 3:30 PM, EST. Titles and abstracts will be added as they become available.
Muon Colliders: the Next Generation of Particle Accelerators
August 19, 2024
Speaker: Tova Holmes, University of Tennessee
Host: Ruixing Zhang
Abstract
Over the last century, the construction and discovery of the Standard Model of particle physics has been one of the greatest accomplishments in physics. To explore this new frontier, we built larger and larger colliders utilizing the two charged particles that are easiest to produce and manipulate, the proton and the electron. As we contemplate the future of high energy colliders, the use of these particles fundamentally limits our potential energy reach: the low electron mass due to synchrotron radiation and the proton due to its composite nature. Luckily, the Standard Model provides an alternative: the muon. In this talk, I’ll discuss the challenges and possibilities of a muon collider, and give an overview of recent progress towards making one a reality.
Emergent Phenomena in Model-Based Quantum Materials
August 26, 2024
Speaker: Jian Liu, University of Tennessee
Host: Ruixing Zhang
Abstract
The complex interplay between the quantum degrees of freedom in oxides is known to cause a rich variety of intriguing emergent phenomena. While model Hamiltonians are often used to capture the underlying physics, they could be difficult to solve theoretically. This challenge calls for model-based designs for materials synthesis and measurement controls to experimentally simulate the corresponding behaviors. In this talk, I will review examples from our recent work that exploited this strategy to investigate the correlation-topology interplay in the Hubbard Hamiltonian, metallization of the dipolar spin ice Hamiltonian, and competition between orthogonal magnetic anisotropy. The results showcase the use of symmetry as the guide to implement the key ingredients of the targeted model in the experiment designs, which synergistically combine atomic layering synthesis, single-crystal growth, ultralow-temperature high-field transport measurements, and/or synchrotron x-ray scattering with multi-modal controls. New opportunities enabled by most recent capability advances will be discussed as well.
100 years of Sagnac Interferometry: from Testing Ether to Detecting Time Reversal Symmetry Breaking in Quantum Materials
September 9, 2024
Speaker: Jing Xia; University of California, Irvine
Host: Ruixing Zhang
Abstract
Symmetry is central to our understanding of natural phenomena. And a Sagnac interferometer, first invented by George Sagnac for the detection of the hypothetical “ether” in the Michelson–Gale experiment [1] a century ago, is intrinsically sensitive to broken time-reversal symmetry (TRS). In this talk, I will first describe a loop-less version of the Sagnac interferometer and microscope that has achieved unprecedented nanoradian level Kerr and Faraday sensitivity even at DC. With this Sagnac technique, I will discuss a few examples of our Sagnac studies of 2D magnetism and superconductivity. In exfoliated Cr2Ge2Te6 (CGT), we report [2] the discovery of intrinsic ferromagnetism in 2D van der Walls crystals, defying the well-known Mermin-Wagner theorem. In epitaxial Bi/Ni bilayer samples, we report [3] the observation of 2D superconductivity that spontaneously breaks TRS, which might have an order parameter with a nonzero phase winding number around the Fermi surface, making it a rare example of a 2D topological superconductor. In the Fe-Chalcogenide superconductor FeTe1−xSex, we found intertwined magnetism and superconductivity in its topological surface state [4]. Additionally, our study on exfoliated FeTe1−xSex flakes indicates the existence of a chiral edge state that may be useful for robust quantum computing (unpublished).
1. “The Effect of the Earth’s Rotation on the Velocity of Light, II” Michelson, A. A.; Gale, Henry G. (1925). Astrophysical Journal. 61: 140.
2. “Discovery of intrinsic ferromagnetism in 2D van der Waals crystals”, Nature, 546, 265-269 (2017).
3. “Time-Reversal-Symmetry-Breaking Superconductivity in Epitaxial Bismuth/Nickel Bilayers”, Science Advances, 3, 3, e1602579 (2017).
4. “Revealing the Origin of Time-Reversal Symmetry Breaking in Fe-Chalcogenide Superconductor FeTe1−xSex”. Physical Review Letters, 130(4):046702 (2023)
Measurement-Altered Quantum Criticality
September 16, 2024
Speaker: Jason F. Alicea, Caltech
Host: Alan Tennant
Abstract
In the study of quantum matter, measurements have traditionally been viewed as a means of learning about a system. Measurements can, nevertheless, play a more active role—generating novel quantum phenomena that may be difficult or impossible to realize in measurement-free settings. As an interesting example, I will discuss how measurements can dramatically alter universal properties of quantum systems tuned to a phase transition. I will also highlight a path to experimental realization in analog quantum simulators based on Rydberg atom arrays. Finally, I will describe how these ideas inform optimization of quantum teleportation protocols against imperfections—establishing a long-term quantum science application of ‘measurement-altered quantum criticality’.
The Electron Ion Collider: A Unique New Microscope for Matter
September 23, 2024
Speaker: John Lajoie, Oak Ridge National Laboratory
Host: Christine Nattrass
Abstract
The visible world around us is made up of atoms, with protons and neutrons forming the nuclei at their core. Together, protons and neutrons make up most of the mass of everything we see in the universe today, from massive galaxies to individual people. Protons and neutrons themselves are complicated many-body quantum states whose properties are determined by the quarks and gluons that they are comprised of. The quest to understand in detail the structure of protons, neutrons, and nuclei is nothing less that an attempt to answer the questions “What are we made of? What is matter?” The Electron Ion Collider (EIC), to be built by JLab and BNL, will be a unique new machine to collide polarized electrons off polarized protons and light nuclei, providing the capability to study multi-dimensional tomographic images of hadronic matter, and collective effects of gluons in nuclei. In this colloquium I will motivate the physics program at the EIC and the unique new machine and detectors that will be required to answer these fundamental questions.
Andrew W. Steiner, University of Tennessee
September 27, 2024
Speaker: Andrew W. Steiner, University of Tennessee
Host: Ruixing Zhang
Abstract
TBA
Marco Limongi, The Astronomical Observatory of Rome
September 30, 2024
Speaker: Marco Limongi, The Astronomical Observatory of Rome
Host: Anthony Mezzacappa
Abstract
TBA
Yiming Xu, Physical Review X
October 28, 2024
Speaker: Yiming Xu, Physical Review X
Host: Haidong Zhou
Abstract
TBA
Mark Goulian, University of Pennsylvania
November 11, 2024
Speaker: Mark Goulian, University of Pennsylvania
Host: Jaan Mannik
Majorana Zero Modes and Topological Quantum Computation: What, Why, How, When?
November 18, 2024
Speaker: Sankar Das Sarma, University of Maryland
Host: Ruixing Zhang
Abstract
Topological quantum computing involves using non-Abelian Majorana zero modes for carrying out error-free fault-tolerant quantum computing. This is the preferred quantum computing platform of Microsoft. I will discuss the current status of the search for non-Abelian Majorana zero modes in solid state systems, discussing both theory and experiment. I will also provide my personal prognosis on what the future holds for the subject.