Single molecule optomechanical resonators with suspended DNA strings

The well-defined vibrational characteristics of microelectromechanical (MEMS) resonators have made them a powerful yet simple tool for sensing. Nanoscale and molecular structure exist in a much more complex regime. Biopolymers such as DNA are known to be highly entropic, exhibiting large thermal fluctuations among their many flexural modes. While the impact of these interactions is well-understood in highly-damped environments, how they affect under-damped single-molecule resonant strings is largely unexplored. Additionally, it is possible to rationally design complex structures involving controlled defects like stacking faults or hair-pins to localize masses and kinks into DNA strands using DNA origami. Understanding and controlling molecular phononic systems will help clarify important questions related to decoherence and may inspire a new class of integrated sensors. Here we report our progress in deterministic sub-micron interfacing of suspended DNA strings with nanoscale photonic crystal cavity to show broadband, real-time detection of their thermal fluctuations. We discuss the merits and challenges of performing these optoelectromechanical measurements in vacuum and cryogenic environments.