Materials World Network: Quantum Electro-Mechanical Properties of Graphene

Cornell University, Ithaca NY

Investigators

Abstract

This Materials World Network award supports an experimental program to investigate whether the mechanical quality factor, Q, of graphene resonators can be made sufficiently large so that the thermal motion of these inherently low mass structures can be observed at low temperatures e.g. 50 mK. Our goal is to demonstrate a Q of 10,000 or discover why it is not possible to reach this Q value. New techniques for measuring the amplitude of motion will have to be implemented. Methods to obtain high Q such as tension, defect reduction and elimination of surface artifacts will have to be invented to achieve the goal of observing thermal motion. The technology to fabricate synthetic few-layer graphite has been developed at Cornell and the NRL, and will allow comparison to natural graphene. The Materials World team funded by this research program brings together expertise in nano-mechanics, synthetic growth of graphene (and few layer-graphite), high frequency signal recovery and low temperature physics, the latter two areas being important to probe the potential quantum nature of the material. Understanding non-linear behavior will also play a role in the success of the program, and non-linearities usually regarded as being undesirable, may actually be beneficial for future quantum information applications. The research program will be integrated with partner programs at Helsinki University and NRL. Graduate students will have the opportunity to work with their counterparts by spending a semester in Finland and by hosting counterparts at Cornell. Graphene is a unique material - a self supporting two-dimensional material that can be completely defect free. What are its mechanical properties? Particularly at low temperatures where the non-classical behavior is expected to become most apparent will graphene display mechanical behavior that is classical or quantum-mechanical? The Materials World team funded by this research program brings together expertise in nano-mechanics, synthetic growth of graphene (and few layer-graphite), high frequency signal recovery and low temperature physics. Quantum mechanics is usually associated with small objects (e.g. atoms) and classical behavior with large objects (e.g. baseballs). Somewhere between lies a no man's land, and the team at Cornell University, Helsinki University and the US Naval Research Laboratory seeks to answer whether a graphene sheet, consisting of approximately 10 to 100 billion atoms is quantum or classical in nature. This understanding will help to determine if the material properties will be useful for new types of electro-mechanical devices, which has implications for the future communications and electronics industries. This research provides a demanding experimental environment that will educate and train graduate students for successful careers in the Nation's scientific and technological infrastructure.