Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session G09: Physical Review Invited Session: Forefront Research Across DisciplinesInvited Live Streamed Undergrad Friendly
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Sponsoring Units: APS Chair: Samindranath Mitra, American Physical Society Room: McCormick Place W-192A |
Tuesday, March 15, 2022 11:30AM - 12:06PM |
G09.00001: Shining New Light on Quantum Matter Invited Speaker: Prineha Narang Quantum systems host spectacular excited-state effects, but many of these phenomena remain challenging to control and, consequently, technologically under-explored. Our work, therefore, focuses on how quantum systems behave, particularly away from equilibrium, and how we can harness these effects. This talk will present an introduction to theoretical and computational approaches to describe excited-states in quantum matter, and predicting emergent states created by strongly non-equilibrium external drives. Understanding the role of such nonequilibrium light-matter interactions in the regime of correlated electronic systems is of paramount importance to fields of study across condensed matter physics, quantum optics, and quantum chemistry. I will give an outlook on driving correlated quantum matter to control the coupled electronic and lattice degrees-of-freedom, and connect these recent predictions with ultrafast experiments underway. |
Tuesday, March 15, 2022 12:06PM - 12:42PM |
G09.00002: Quantum tomography of motion in time of flight Invited Speaker: Cindy A Regal Quantum control of mechanical motion has been achieved in a surprising range of platforms in the past decades. These mechanical quantum systems have both piqued the curiosity of physicists, and enabled new approaches to difficult tasks in manipulating quantum information. Trapped particles offer one opportunity to study isolated quantum motion. Laser-cooled ions routinely demonstrate intriguing phonon control, and recent experiments have now brought trapped dielectric nanoparticles to their quantum ground state. In this talk I present how observing a particle after a time of flight combined with trap evolution can map the full quantum state of a trapped particle. I will describe this intuitive method through experiments with a single neutral atom in a non-classical motional state, and discuss future applicability to larger mass systems. |
Tuesday, March 15, 2022 12:42PM - 1:18PM Not Participating |
G09.00003: How humans build models of the world Invited Speaker: Danielle S Bassett Human learners acquire not only disconnected bits of information, but complex interconnected networks of relational knowledge. The capacity for such learning naturally depends on the architecture of the knowledge network itself. I will describe recent work assessing network constraints on the learnability of relational knowledge, and a free energy model that offers an explanation for such constraints. I will then broaden the discussion to the generic manner in which humans communicate using systems of interconnected stimuli or concepts, from language and music, to literature and science. I will describe an analytical framework to study the information generated by a system as perceived by a biased human observer, and provide experimental evidence that this perceived information depends critically on a system's network topology. Applying the framework to several real networks, we find that they communicate a large amount of information (having high entropy) and do so efficiently (maintaining low divergence from human expectations). Moreover, we also find that such efficient communication arises in networks that are simultaneously heterogeneous, with high-degree hubs, and clustered, with tightly-connected modules -- the two defining features of hierarchical organization. Together, these results suggest that many real networks are constrained by the pressures of information transmission to biased human observers, and that these pressures select for specific structural features. |
Tuesday, March 15, 2022 1:18PM - 1:54PM |
G09.00004: What is a Time Crystal? Invited Speaker: Norman Y Yao The defining feature of a time crystal is that it exhibits subharmonic oscillations, but so do many other things in nature. In this talk, my main goal is to sharpen the question surrounding time crystals, and to provide some answers in the context of both classical and quantum many-body systems. Particular care will be taken to contextualize modern results on discrete time crystals with related phenomena in non-linear dynamical systems. Finally, we will demonstrate that locally-interacting, periodically-driven Hamiltonian dynamics coupled to a Langevin bath support finite-temperature discrete time crystals with an infinite auto-correlation time. I will end by surveying recent experiments demonstrating the observation of time crystalline order in a variety of quantum simulation platforms. |
Tuesday, March 15, 2022 1:54PM - 2:30PM |
G09.00005: Tuning fragile moment transitions to quantum phase transitions. Invited Speaker: Paul C Canfield Lev Nikolayevich Tolstoy starts his novel Anna Karenina by stating that “All happy families are alike; every unhappy family is unhappy in its own way.” A similar statement can be made about fragile magnetic phase transitions. All local moment phase transition are alike; every fragile moment transition is fragile in its own way. A fragile magnetic state [1] is one that has (i) reduced moment ordering and (ii) can be tuned by pressure, doping and/or applied field so that its transition temperature and associated fluctuations can be brought to low enough temperatures so as to allow a new phase or state to emerge. Fragile magnetism appears to be a necessary, but certainly not sufficient condition for the type of high-Tc superconductivity found in cuprate, Fe-based, and even heavy-fermion superconductors. Over the past years we have explored a number of fragile magnetic systems and continue to be amazed at the richness and complexity that emerges as ferromagnetic and antiferromagnetic phase transitions are tuned toward zero Kelvin. In this talk I will motivate our interest in fragile magnets with data from the BaFe2As2 and CaFe2As2 systems and then discuss our recent results on a variety of rare earth based (Ce and Yb) and transition metal based (Co and Ni) intermetallic systems. The avoided quantum criticality will play a prominent role in metallic systems that start with ferromagnetic ground states. |
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