Seminar

A Pitt Physics seminar

Abstract: The discovery of graphene inaugurated research on the novel relativistic and topological electronic properties of 2D honeycomb quantum materials. One wonders whether other elemental graphene analogues beyond the group 4a elements exist. Motivated by revolutionary exploration of the synthesis and electronic characterization in Xenes, we address whether metallic elements can also embody similar molecular and electronic structures. We find that alkaline earth Ca monolayer (calcene) on Cu(111) indeed forms a new 2D honeycomb...

A CMU-Pitt Colloquium

Abstract: Electrons inside matter can behave as complex particles that do not exist in the Standard Model. These seemingly impossible effects are examples of emergent phenomena—that is, unexpected collective behavior—of electrons in quantum materials. The discovery and characterization of new emergent phenomena in quantum materials not only expand the boundary of our knowledge, but also provide unique opportunities for future quantum technologies. However, these effects often manifest in subtle ways, and thus detecting them requires...

A CMU-Pitt Colloquium

Abstract: Quantum materials host exotic states of matter with unique macroscopic phenomena, ranging from various correlated electron states to topological orders. The ability to manipulate and probe their emergent behavior with nanoscale precision is at the forefront of condensed matter research and underlies the future progress of new electronic and photonic technologies. Polaritonic platforms utilizing hybrid light-matter excitations with extreme light confinement enable a unique form of experimental inquiry into the...

A CMU-Pitt Colloquium

Abstract: With the advancements in quantum materials research, the emergent quantum many-body phenomena, such as competing orders, topological order and fractionalization, can be realized in much more controllable ways. 

However, resolving them experimentally can be challenging. In this talk, I will tell two stories of understanding the emergent phenomena in quantum materials, with setups both in and out of equilibrium. First, I will discuss our theory of the charge orders in recently extensively studied Vanadium based kagomé...

A CMU-PITT Colloquium

Abstract: Quantum materials provide an exciting platform to realize emergent phenomena and topological properties in condensed matter systems. Our ability to synthesize these materials with atomic precision enables us to rationally design quantum structures with tailored properties. In this talk, I will provide examples of such an approach using thin film synthesis by molecular-beam epitaxy that allows access to tuning parameters, such as, interfacial engineering and dimensional confinement, and the creation of artificial...

A CMU-PITT Colloquium

Abstract: The emergence of the two-dimensional (2D) transition metal dichalcogenides (TMDCs) ushers in a new era of light-matter interaction, offering exciting opportunities in quantum information science (QIS). In monolayer TMDCs, the reduced screening enhances the Coulomb interaction and gives rise to strongly bound excitons with the binding energy of hundreds of meV. In addition, the excitons in TMDCs possess a new quantum degree of freedom, valley-spin, which is promising for quantum information processing and can be accessed...

A CMU-PITT Colloquium 

Abstract: Moire heterostructure is an exciting class of highly-tunable platforms hosting various types of strongly-correlated physics. In this talk, I will present two different emergent quantum phenomena arising in this platform: (i) Correlated insulator and correlated semimetal in twisted graphene layers, and (ii) fractional Chern insulators and emergent quantum electrodynamics in Moire materials under magnetic field.

The first part of the talk covers the rich physics of twisted graphene layers originated from multi-flavored...

A CMU-Pitt Colloquium

Abstract: Atomically thin Van der Waals materials have emerged as a highly versatile platform to advance our understanding of quantum matter driven by strong electron correlations. Recent experimental breakthroughs in stabilizing few-layered graphene structures with a “magic” relative twist between layers has led to the discovery of a wide variety of correlated states ranging from magnetism to superconductivity. Despite compelling experimental evidence for unconventional superconductivity, the glue which binds electrons into Cooper...

Precision studies of the Higgs boson -- a window to new discoveries

Abstract: With the discovery of the Higgs boson, the last remaining constituent of the Standard Model of particle physics has been experimentally confirmed. However, the Standard Model does not answer several important questions about fundamental physics: What is the origin of dark matter?

Why is there matter but (almost) no antimatter in the universe? How can we describe gravity and quantum mechanics in a consistent way?

The Higgs boson is fundamentally different...

Quantum information research with superconducting circuits

Abstract: The long-term objective of quantum information research is to build machines, especially computers, whose internal operations are governed by the rules of quantum, rather than classical, mechanics. Quantum computers, if we can realize them, promise to revolutionize which problems we can solve through computation by exponentially speeding up in the calculation of certain problems.  I will discuss my laboratory’s efforts to build quantum-limited amplifiers based on parametric...