Materials Engineering
Principal Investigator: Douglas Chrisey
Novel Laser and Photonic Material Processing: My research interests are largely centered on the novel approaches to laser and photonic microfabrication and nanostructuring and their applications to solve technical problems. These techniques exploit the laser-material interaction in novel ways. Testing the resulting films involved various techniques, including circuit or tissue design and surface patterning. The final film or prototype device properties frequently exceeded those of conventional techniques.
Materials and Devices Fabricated With Soft Materials: In biology, chemistry, and medicine there are applications where traditional silicon approaches are limited. Compared to silicon, soft materials have many attributes allowing the low cost non-lithographic fabrication for fluidic, mechanical, and electronic devices spanning the micro- to nano-scale. One property that is particularly unique - their elastic modulus can be varied over two orders of magnitude by controlling the amount of cross-linking between polymer chains. Significant research opportunities exist to expand the capabilities of soft materials by using specially functionalized elastomers or other polymers processed in different ways and this will have a tremendous impact on both soft material research and practical commercialization of micro- to nanoscale devices.
Glass/Polymer and Ceramic Electronics: There is an exciting trend in research that aims fundamental research towards a transition pathway to commercial innovation. In this project area we have demonstrated a low cost approach to fabrication of glass/polymer and ceramic composites to achieve high capacitive energy storage. Though this is just one example, there are many more opportunities for glass and ceramic materials to be utilized such as all classes of ceramic electronic materials such as ferroelectrics, ferrites, transparent conducting layers, high temperature superconductors, piezoelectrics, and so on. The possible combinations and fabrication requirements in the ceramic or glass and ceramic system is enormous and will last for generations.
Layer-By-Layer CAD/CAM Patterns of Biomaterials: In conventional tissue engineering, a three-dimensional porous scaffold is homogeneously seeded with cells. Ideally, through the controlled release of various growth stimulation and differentiation biomolecules from the scaffold, the cells will proliferate in a bioreactor and differentiate into a tissue that demonstrates characteristic biological function. Laser printing allows the near cell-by-cell re-construction of biological tissue by a CAD design. This approach is superior to conventional tissue engineering because it can create a construct that is orders of magnitude more heterogeneous and, thus, representative of the desired tissue or organ to be created. The instantaneous heterogeneity only achievable by this technique is akin to the desired long-term differentiation obtained through conventional tissue engineering approaches. The more precise replication of natural tissue by direct writing will result in advanced tissue development and function and; it better utilizes nature’s genetic machinery for directed self-assembly. There are many applications for precise biomaterial patterns and robust tissue constructs including: basic studies of intercellular communication, biocompatibility studies for new materials and scaffolds, hybrid microfluidic and bioMEMs devices, tissue and organ regeneration, tissue-based biosensors, computer-aided surgery, and living microdissection and culturing.
Nanotechnology and Self-Assembly: Beyond just the use of raw nanoparticle materials, it is my belief that the area of nanotechnology having the greatest potential for applications are those processed by directed self-assembly. Self-assembly is a bottom-up approach using materials of complementary functionalities that will spontaneously assemble themselves into periodic structures at the molecular scale; it is inexpensive, routine and seen on an enormous range of length scales. While this miraculous construction does not occur in typical synthetic molecules, it does occur in nature, partly because of the stereospecificity, homodispersity, periodicity and complementarity of the molecules built by the machinery of the cell. Directed self-assembly has features that offer the promise for novel electronic applications such as quantum computing, physical and chemical sensing, and integration with biotechnology. Realization of these applications will require the successful integration of both top-down and bottom-up methodologies.
Materials Engineering
Principal Investigator: Douglas Chrisey
Our research interests are wide ranging and include the novel laser fabrication of thin films and coatings of advanced materials for electronics, sensors, biomaterials, and for energy storage. The new materials were used in device configurations for testing and typically had an improved figure-of-merit. He is considered one of the pioneers in the field of Pulsed Laser Deposition and was the lead inventor of MAPLE processing technique (matrix assisted pulsed laser evaporation). He is currently publishing in areas of metallic nanoparticle fabrication, biosensing, bionanotechnology, tissue engineering, stem cell processing, ceramics, and polyamorphism.
Experimental Solid State Physics
Principal Investigator: David L. Ederer (Emeritus)
Professor David L. Ederer was a senior staff scientist in the Center for Atomic, Molecular and Optical Physics at the National Institute of Standards and Technology (NIST), for almost thirty years. He came to Tulane in January 1992 to launch a new program in experimental solid state physics with the Center for Advanced Microstructures and Devices (CAMD) in Baton Rouge, as a focal point. Ederer carries out research on transition metals and rare earth materials at the Advanced Light Source as well, using soft x-rays to elucidate the electronic properties of complex and highly correlated materials such as high Tc superconductors. Ederer, a fellow of the American Physical Society, is an internationally recognized expert in the use of synchrotron radiation for research in atomic, molecular, and solid state physics. His research in atomic, and condensed matter physics, as well as instrument design has resulted in over one hundred and fifty papers.
Recent topics of research have included doped manganate systems, the superconducting perovskite Sr2RuO4 system and multi-layered variants, and magnetically doped semiconductors with particular focus on half-metallic behaviour.
Photonic Materials & Devices
Principal Investigator: Matthew Escarra
The Escarra group explores novel photonic materials and devices with applications in solar energy conversion, sensing, integrated photonics, and more. On the fundamental end, we are exploring nanoscale photonic materials and devices, where quantum phenomena and sub-wavelength behavior tend to dominate. On the applied end, we are developing unique material, device, and system architectures for high efficiency or high-power density solar energy conversion.
Active project thrusts include:
- In collaboration with academic and industry partners, the group is developing a new hybrid solar energy converter that allows for high efficiency cogeneration of process heat and electricity. This system features a photovoltaic module designed to work in tandem with solar thermal energy capture and storage.
- The group is exploring nanophotonics from low-loss and phase change materials. These nanostructures are able to sculpt the flow of light in an ultra-thin/compact form factor for use in integrated photonics.
- The group is studying two-dimensional transition metal chalcogenides for use as semiconductor materials in ultra-thin optoelectronic devices. We have a particular interest in large scale synthesis and photovoltaic applications of these materials.
The research in this group involves multi-physics simulations, materials synthesis, micro/nanofabrication, and optoelectronic material and device characterization..
Quantum Information and Nonlinear Optics
Principal Investigator: Ryan T. Glasser
The Glasser group's research includes several directions surrounding the fields of quantum information technologies, machine learning, and optical communications. Some examples include developing and applying neural networks to classical and quantum communications, multi-party quantum networks, and quantum state estimation. One core aspect of this research is to improve our understanding of the fundamental physics surrounding quantum entanglement and quantum states of light, which are integral to the creation of future quantum networks. A second aspect involves utilizing these concepts in various computation, communication, and measurement protocols to enhance performance beyond classical limits. We are also developing machine learning tools for enhancing a variety of classical and quantum optical systems and protocols.
One experimental tool used in this research is four-wave mixing in warm atomic vapor. This process generates pairs of photons in separate spatial modes that exhibit stronger correlations than allowed by classical physics, in multiple degrees of freedom. When a laser is used to seed the process, bright “twin beams” of light are created. The correlations in these twin beam states are exploited to enhance, for example, interferometric measurements and the resolution of imaging systems. Investigating novel methods to generate highly multimode “squeezed” and entangled light is an important aspect of this research area, applicable to quantum networks.
We also have several projects involving the combination of machine learning, optical communications (both classical and quantum), and quantum measurement. This includes advancing current state-of-the-art free-space optical communications systems, enhancing quantum state estimation protocols, and the development of quantum networks.
The group is also interested in the generation of novel high-dimensional entangled states of light. This work involves creating robust continuous-variable states that are applicable to real-world systems in which scattering and decoherence are present. The fundamental behavior of the quantum information present in these states is a key theme in this research.
Novel Energy Materials
Principal Investigator: Michael Naguib
The need for reliable energy conversion and storage systems is continuously growing, especially with recent efforts to further develop renewable energy and the explosive growth of portable device technologies. Thus, the development of novel materials for energy conversion and storage is of critical importance. Thus, the research in our group has the general theme of Novel Energy Materials. This involves developing new 2D materials for applications in the next generation of batteries beyond Li-ion, supercapacitors and electrocatalysis. In addition to discovering and creating new materials, another important thrust is developing inexpensive materials for the commercially available electrochemical energy storage systems (e.g. Li-ion batteries and supercapacitors), that contributing to environmentally friendly and sustainable technologies.
Polymer Physics & Biophysics
Principal Investigator: Wayne Reed
Research in my group centers on fundamental and applied aspects of Polymer Science, with an increasing emphasis on private sector liaison. We study biological and synthetic polymers in solution, with an aim towards discovering basic physical principals involved in their structures and interactions, as well as solving practical problems of immediate interest to such industries as pharmaceuticals, biotechnology, food, paints, adhesives, resins, coating, water purification, etc. To this end we are also strongly involved in developing new characterization techniques and instrumentation for polymers, especially those involving light scattering.
Efforts are concentrated on innovative ways of monitoring processes occurring in polymer solutions in real time. We make extensive use of light scattering and other optical techniques, viscometry, size exclusion chromatography, and other auxiliary techniques (DSC, electron-microscopy, etc.). We have interests in the fundamental areas of polymer reaction kinetics and mechanisms, conformations, interactions and hydrodynamics, with a special focus on polyelectrolytes.
Femtosecond & Teraherz Spectroscopy
Principal Investigator: Diyar Talbayev
We are interested in optical and electrical properties of complex materials, which include materials with strong electronic correlations (e.g. magnetic and superconducting transition metal oxides), multiferroic materials that combine ferroelectricity with magnetism, and artificial THz plasmonic structures. We use time-resolved optical and terahertz spectroscopy to probe low-energy magnetic, lattice, and electronic excitations that reveal the microscopic physics governing a material. Time-resolved spectroscopy employs femtosecond light pulses to perturb and manipulate the equilibrium state of solids and adds another dimension, the time domain, to expose the relationships between the fundamental interactions in a material.
Current research topics include:
- Time-resolved studies of coupled spin and charge dynamics in multiferroic materials. The motivation for this work is the exploration of THz-frequency switching magnetic and ferroelectric domains and the understanding of the basic physics that governs the switching dynamics.
- Time resolved and THz spectroscopy of quasiparticle dynamics in strong correlated electron systems, specifically magnetic and superconducting materials.
- Properties of surface plasmons at THz frequencies, THz plasmonics. Plasmonics studies electromagnetic waves interacting with electrons inside materials, the interaction that is governed by Maxwell's equations. Out of this simplicity have emerged such fascinating phenomena as negative refraction and sub-wavelength light focusing. We are focusing on the most immediate uses of THz surface plasmons in high-sensitivity chemical and biological sensing.
Nanodevice Physics
Principal Investigator: Jiang Wei
The Wei group's research interest focuses on nanoscale condensed matter physics, particularly on the underlying physics of the emerging quantum phenomena in nanostructures. Nanodevice physics fascinates us because when the characteristic length of physical systems approaches to nanoscale, quantum mechanical effects start to appear or even dominate. We are primarily interested in two groups of nanostructured materials: 1D and 2D quantum materials, and strongly correlated materials. We utilize our state-of-the-art micro-nano fabrication facilities to transform these materials into measureable nanoscale devices. Because low-dimensional material exhibits different physical properties from those of bulk material, we investigate the electrical, magnetic, and optical properties of low-dimensional structures to understand the fundamental physics. The nanostructured devices of strongly correlated material can be used as a research vehicle to explore the unknown territory of phase diagram, to investigate the collective many-body behavior, and to manipulate the phase transition by applying electric field, magnetic field, strain, and chemical doping. We also explore the technological applications of these nanodevices.
Current research directions:
- Quantum transport study of 1D and 2D materials
- Investigation of the phase transition on nanostructured strongly correlated materials modulated by mesoscopic strain and chemical doping engineering.
- Scanning photocurrent and surface enhanced Raman spectroscopy on nanodevices.
- Development of fabrication technique of ultra-small nanostructures.
Experimental Nuclear Physics
Principal Investigator: Fred Wietfeldt
My group is engaged in experimental nuclear physics research using cold and ultracold neutrons. This work falls into three related, but distinct categories:
- Tests of the Electroweak Standard Model with precision measurements of neutron decay parameters
- Studies of the hadronic weak interaction by measuring parity-violating parameters in neutron interactions with matter
- Tests of nucleon forces and fundamental quantum mechanics using neutron interferometery. Our main focus right now is on categories (1) and (3).
Cold neutrons are free neutrons that are moving so slowly (less than 2000 m/s) that their deBroglie wavelengths are larger than the spacing between atoms in matter, typically in the range 0.2 to 2.0 nm. In this regime the neutron-matter interaction is coherent, the neutron interacts with many atoms simultaneously, and so it is more wave-like than particle-like. Cold neutrons can be manipulated optically, in many ways similar to light optics. They can be reflected, refracted, and diffracted in matter. Neutron guides, analogous to fiber optic guides, can be used to transport cold neutrons long distances with very little losses.
Ultracold neutrons (UCN's) are neutrons whose kinetic energy is less than about 300 neV. This energy is comparable to three important energy scales:
- The neutron's optical potential in certain materials;
- The neutron's potential energy in a strong magnetic field (~ 5 Tesla);
- The neutron's gravitational potential energy at a height of several meters. Therefore UCN's can be trapped optically, magnetically, and gravitationally. A free neutron will decay into a proton, electron, and antineutrino with a lifetime of about 15 minutes. This is the simplest nuclear beta decay and the prototype semi-leptonic weak decay. The measurable parameters of neutron decay such as its lifetime and angular correlations can be directly related to fundamental parameters in the Electroweak Standard Model. Precision experiments can test the self-consistency of the theory and possibly point to new physics related to grand unification. In this way neutron decay plays an important role in the low-energy frontier of particle physics.
Precise measurements of neutron scattering lengths using a neutron interferometer can be used to improve our understanding of the nucleon-nucleon potential and other parameters such as the charge radius of the neutron. The neutron interferometer is also used for fundamental tests of quantum mechanics. These experiments are carried out at the National Institute of Standards and Technology (NIST) (Center for Neutron Research). In addition to comprehensive instrumentation for neutron scattering research, this facility supports and operates a suite of neutron beams (both monochromatic and polychromatic) dedicated to fundamental neutron physics. It also operates the most sensitive Neutron Interferometer in the world.
We design and develop experiments in our laboratories at Tulane, usually in collaboration with groups at other institutions, and then bring experiments to NIST for data collection. We usually spend summers at NIST and students in my group often spend one or more years full time at NIST, after completing their Tulane course-work, to complete their dissertation research.
Upcoming experiments:
- A measurement of the radiative decay branch of the neutron (never before observed)
- A precision measurement of the electron-antineutrino correlation (little "a") in neutron decay
- A precision measurement of the neutron-electron scattering length. This will lead to a determination of the charge radius of the neutron
- An improved measurement of the neutron scattering length in polarized 3He gas. This will provide important and unique information about nucleon-nucleon forces.
- A new measurement of gravitationally-induced quantum interference in a neutron interferometer. This tests the weak equivalence principle at the quantum limit.
Nano-Optics in 2D Materials
Principle Investigator: Xin Lu
The discovery of superconductivity in twisted bilayer graphene has triggered another wave of interest in layered materials and van der Waals (vdW) heterostructure since the rise of graphene in 2004. Layered materials offer a novel and rich platform for fundamental physics and device application, which include but not limited to the 2D superconductivity, 2D magnet, spin-valley physics (spin-/valley-tronics) and moiré physics. The Lu group’s research interests lie at the interface of quantum optics and material science in 2D vdW structure. We will use light as the main tool to investigate the lattice vibrational modes (phonons), excitonic physics and exciton-phonon interaction in the low-dimensional materials. Major equipment in Dr. Lu’s group includes:
- An HRS-750 spectrometer (Teledyne Princeton Instruments).
- A continuous wave Ti:Sapphire Tunable laser (M Squared), 700 – 1000 nm.
- A closed-cycle, cryogen-free cryostat (~4 K) with a 9 T superconducting magnet (attocube).
- A source measure unit (Keithley 2400).
- A home-built optical setup, capable for polarization-resolved, angle-resolved and ultra-low frequency (~10 cm-1) Raman scattering measurements at room temperature.
- A home-built optical setup for low-temperature measurements (including Raman scattering and photoluminescence).
