Decoherence and Spin Echo in Biological Systems

The spin echo approach is extended to include bio-complexes for which the interaction with dynamical noise is strong. Significant restoration of the free induction decay signal due to homogeneous (decoherence) and inhomogeneous (dephasing) broadening is demonstrated analytically and numerically, for both an individual dimer of interacting chlorophylls and for an ensemble of dimers. This approach is based on an exact and closed system of ordinary differential equations that can be easily solved for a wide range of parameters that are relevant for bio-applications.Comment: 5 pages, 5 figure

Time-domain THz spectroscopy reveals coupled protein-hydration dielectric response in solutions of native and fibrils of human lyso-zyme

Here we reveal details of the interaction between human lysozyme proteins, both native and fibrils, and their water environment by intense terahertz time domain spectroscopy. With the aid of a rigorous dielectric model, we determine the amplitude and phase of the oscillating dipole induced by the THz field in the volume containing the protein and its hydration water. At low concentrations, the amplitude of this induced dipolar response decreases with increasing concentration. Beyond a certain threshold, marking the onset of the interactions between the extended hydration shells, the amplitude remains fixed but the phase of the induced dipolar response, which is initially in phase with the applied THz field, begins to change. The changes observed in the THz response reveal protein-protein interactions me-diated by extended hydration layers, which may control fibril formation and may have an important role in chemical recognition phenomena

Putting mechanics into quantum mechanics

Nanoelectromechanical structures are starting to approach the ultimate quantum mechanical limits for detecting and exciting motion at the nanoscale. Nonclassical states of a mechanical resonator are also on the horizon

Atomic Scale Magnetic Sensing and Imaging Based on Diamond NV Centers

The development of magnetic sensors simultaneously satisfying high magnetic sensitivity and high spatial resolution becomes more important in a wide range of fields including solid-state physics and life science. The nitrogen-vacancy (NV) center in diamond is a promising candidate to realize nanometer-scale magnetometry due to its excellent spin coherence properties, magnetic field sensitivity, atomic-scale size and versatile operation condition. Recent experiments successfully demonstrate the use of NV center in various sensing and imaging applications. In this chapter, we review the basic sensing mechanisms of the NV center and introduce imaging applications based on scanning magnetometry and wide field-of-view optics