Cyclotron resonance spectroscopy of symmetry broken states in monolayer graphene

Erik Henriksen
Thursday, November 14, 2019 - 4:30pm

Cyclotron resonance—the resonant absorption of light by charge carriers in a strong magnetic field—is widely used to measure the effective band mass of (semi-)conducting materials. This works because the CR absorption in systems having a parabolic dispersion—a reasonable description of most materials—is unaffected by inter-particle interactions. An intriguing corollary is that, for instance, in high-mobility GaAs heterostructures when the electronic transport shows remarkably complex behavior in the fractional quantum Hall regime, there is still only a single cyclotron resonance peak that...

Machine Learning for Materials Discovery

Maxwell Hutchison
Friday, November 8, 2019 - 11:30am

Machine learning and artificial intelligence applications in science and engineering have received rapidly increasing hype over the last several  years, with Citrine on the front lines of adoption of ML and AI in materials development. In this talk, I will discuss opportunities, open challenges, and recent work in materials informatics drawn from experiences on a wide range of commercial and noncommercial projects, including:

  • data    reuse    with    transfer    learning,
  • design    of    experiments    with    active    learning,
  • domain    knowledge    
  • ...

Nanorod Heterostructures: from Colloidal Solutions to Light Emitting/Harvesting Devices

Moonsub Shim
Wednesday, October 30, 2019 - 12:00pm

The ability to efficiently separate, recombine, and direct charge carriers is central to a wide range of applications, including electronics, photovoltaics, displays and solid-state lighting. Engineering band structure and heterointerfaces with atomic precision is an obvious route to achieving such capabilities. To do so through widely-accessible and cost-effective means is not. But such a means would allow rapid advances in these critical application areas. The evolution of colloidal semiconductor nanocrystals from single-composition, “spherical” particles to complex heterostructures of...

Quantum sensing and quantum nanophotonics at ORNL

Benjamin Lawrie
Thursday, November 21, 2019 - 4:00pm

Two-mode squeezed light sources exhibiting continuous variable entanglement allow us to reduce the noise floor in optically transduced sensors below the standard quantum limit, enabling greater signal to noise ratios than are possible in the best possible classical sensors.  I will present some of our recent results demonstrating quantum enhanced sensitivity for applications ranging from magnetometry to plasmonic sensing to atomic force microscopy. I will also discuss some of our recent research efforts exploring quantum nanophotonics with plasmonic nanostructures and single photon...

Quantum Information Processing with Spins in Diamond

Gurudev Dutt
Wednesday, October 16, 2019 - 12:00pm

A key feature of quantum physics is the existence of superpositions of single and many-particle quantum states, usually referred to as quantum coherence and entanglement respectively.  Famously, these aspects of quantum theory were also characterized by Einstein as "spooky" and caused him to reject many of its predictions. However, these principles are by now so well established that they have actually become tools in the growing field of quantum information science and technology to realize new paradigms for secure communication, enhanced computation, and precision sensing. 


Phase-change photonics for all-optical memory, computation, and beyond

Dr. Nathan Youngblood
Wednesday, October 2, 2019 - 12:00pm

Phase-change chalcogenides (such as AgInSbTe and Ge2Sb2Te5) have been used commercially as an optical storage medium in the last few decades owing to their high optical contrast and long-term stability, but only recently has a fully integrated photonic device been demonstrated. This approach not only enables all-optical memory on-chip, but also allows multilevel data storage with improved SNR, low switching energy, and high speed operation. In the first part of this talk, new innovations in phase-change, non-volatile photonic memory will be presented, including their use for “in-memory”...