Nanoscale Processes and Measurements Group

Our group develops measurement tools, methods, and theory that are required both for exploring quantum phenomena in new materials and devices and for harnessing these phenomena in sensing, computing, and metrology applications. The solid-state systems of interest include layered atomically-thin materials, topological materials, molecular systems, crystal defects, and correlated oxides. All these materials platforms offer opportunities for quantum information science (QIS). We pursue a two-prong approach: we build unique measurement instruments for exploring QIS phenomena, and we use quantum phenomena for new measurement methods. 

Some of our unique capabilities include:

• Atomic-scale microscopy and spectroscopy of interfaces and devices for nanoelectronics
  
  A suite of the state-of-the-art custom designed scanning probe systems (scanning tunneling microscopy / spectroscopy and atomic force microscopy) combined with transport characterization that operate in ultra-high vacuum, at ultra-low temperatures (down to 15 mK), and in ultra-high magnetic field (up to 15 T) environments. Supporting capabilities include in-situ material growth by MBE and device fabrication with nanostencil masks. The facility is used for atomic scale characterization of devices built of 2D materials, topological materials and atom-assembled quantum systems.
• Scanned probe electron spin resonance (EPR) 
  
  A custom system with tip-based excitation and detection of EPR provides a method to collect the spatial information of interacting/non-interacting spins. It is a high vacuum cryogenic atomic force microscope (AFM) with working temperature range spanning 10 K to 450 K, a 2 T superconducting magnet, two vacuum electrical probes, and 2 AFM measurement heads. The system provides a unique capability to examine the spatial and transport relationship of magnetic moments in virtually any materials system. This includes interacting spins in a variety of 2D materials systems, organic and inorganic semiconductors, and the magnetic domain motion in magnetoresistive layers. 
  
  While many of the current materials being studied for QIS applications rely on very low temperatures and complicated fabrication to extend the lifetimes and to enable state manipulation, our interest is also in exploring quantum phenomena that can function at room temperature for sensing and measurement purposes. Such systems include NV centers in diamond and defects in 2D insulators, excitons in hydrocarbons and 2D materials, and metal-insulator transition in oxides.
• Imaging magnetization dynamics with diamond NV centers
  
  The recent development of nitrogen-vacancy (NV) defects in diamond as a room-temperature, single-spin field sensors can address the needs to quantitatively characterize magnetic nanodevices relating materials properties and device geometry with fundamental spin transport physics. The unique properties of this defect including optical initialization and readout of the spin state and a long coherence time allow for room temperature measurements of magnetic field with a noise floor on the order of 10 nT/(Hz)1/2.  We intend to use this sensitivity to measure the stray fields from magnetic nanostructures and small shifts in those fields as ferromagnetic resonance is excited.    For comparison, 10 nT is approximately the field 50 nm away from a single Bohr magneton.
• Quantum processes in excitonic systems and correlated oxides for imaging and sensing
  
  Optical imaging offers a convenient and sensitive engineering platform for parallel data acquisition. However, many signals and processes that need to be monitored or measured, e.g. in novel electrical circuitry or signaling in in cells and tissues, do not have easily detectable optical signatures. The functionalities and capabilities of optical measurements can be enhanced by placing nanoscale quantum sensors transducing electrical or thermal activity to optical signatures in immediate proximity of a device or a circuit under study.