Session M67: DCMP Prize Session

Oliver E. Buckley Condensed Matter Physics Prize talk

In this talk I will review the discovery of correlated insulator states and superconductivity in magic-angle twisted bilayer graphene, as well as some of the recent developments in the field.   

What have we learned from Dynamical Mean Field Theory and what lies ahead ?

Dynamical Mean-Field Theory (DMFT) provides both an original perspective on the
physics of strongly correlated electron materials and an efficient computational
framework to understand and predict their properties. In this talk, I will review the
main ideas at the heart of the DMFT construction and physical perspective.
Through select examples, I will outline how the efforts of a whole community
over almost three decades have managed to develop the theory to such a point
that it can successfully be applied to a real material, taking into account its structure
and chemical composition. I will also outline how the theory is being extended
and generalized in many fruitful directions.   

Towards a Theory of Strongly Correlated Materials the Dynamical Mean Field Theory Road

Strongly corrrelated electron materials, pose great conceptual and computational challenges. Dynamical Mean Field Theory (DMFT) has enabled a community of scientists to achieve great progress in this area. We will review some basic ideas underlying this approach, such as the reduction of the full many body problem into a quantum impurity model satisfying a self consistency condition. We will then provide some examples from materials containing elements from different regions of the periodic table, ranging from 3d's(*) to 5f's (**) of how DMFT ideas and implementations in combination with electronic structure methods has enabled predictions in materials which were not tractable by other methods, work under way to overcome its limitations(*) and point towards great challenges ahead.   

Frank Isakson Prize for Optical Effects in Solids: Composite Materials and Metamaterials for Nonlinear Optics

There has been great interest in the development of composite optical materials and metamaterials for applications in modern optical technology. Materials with a strongly nonlinear response are required for many applications, and especially in photonics for processes such as all-optical switching. It is of particular interest to design composite structures that enhance the value of the third-order optical susceptibility chi-3. Under ideal conditions, this composite chi-3 can exceed the chi-3 values of the constituents of the composite [1]. This enhancement of the nonlinear response can be understood as a consequence of the judicious use of local field effects [2]. Enhanced nonlinear response of composite materials and structures has been demonstrated for a variety of materials [3-7]. Recent work has shown an additional means of enhancing the nonlinear optical response by making use of a material that possesses a vanishingly small electric permittivity at the wavelength of interest. Such materials are known as epsilon-near-zero (ENZ) materials [8], and they have been observed to display extremely large values of the chi-3 response [9]. These materials, on their own or when incorporated into metasurfaces [10], hold great promise for high-speed, all-optical switching applications and operate with minimal power requirements.

[1] J. E. Sipe and R. W. Boyd, Phys. Rev. A 46, 1614, 1992.
[2] J. J. Maki, R. W. Boyd, et al. Phys. Rev. Lett. 68, 972, 1991.
[3] G. L. Fischer, R. W. Boyd, et al., Phys. Rev. Lett. 74, 1871, 1995.
[4] R. L. Nelson and R. W. Boyd, Appl. Phys. Lett. 74, 2417, 1999.
[5] N. N. Lepeshkin, R. W. Boyd, et al. Phys. Rev. Lett. 93 123902 2004.
[6] J. E.Heebner and R. W. Boyd, Opt. Lett. 24, 847, 1999.
[7] J.E. Heebner, R.W. Boyd, et al., Optics Letters 29, 769 (2004).
[8] N. Kinsey et al., Optica 2, 616 (2015).
[9] M. Z. Alam, I. D. Leon, and R. W. Boyd, Science 352, 795 (2016).
[10] M. Z. Alam, R. W. Boyd et al., Nature Photonics 12, 79–83 (2018).   

Plasmonic Metamaterials Meet Quantum

We first review the recent developments and novel applications for space-time-frequency metasurfaces. Then we outline hybrid, plasmonic-photonic meta-structures for quantum information systems and discuss a new approach for high-speed quantum photonics operating at THz rates. The use of plasmonics to optimize light-matter coupling and speed-up quantum processes so that they outpace quantum decoherence and losses will be also discussed.