Quantum spin dynamics

Abstract:

For the past three decades nanoscience has widely affected many areas in physics, chemistry and engineering, and has led to numerous fundamental discoveries, as well as applications and products. Concurrently, quantum science and technology has developed into a cross-disciplinary research endeavour connecting these same areas and holds burgeoning commercial promise. Although quantum physics dictates the behaviour of nanoscale objects, quantum coherence, which is central to quantum information, communication and sensing, has not played an explicit role in much of nanoscience. This Review describes fundamental principles and practical applications of quantum coherence in nanoscale systems, a research area we call quantum-coherent nanoscience. We structure this Review according to specific degrees of freedom that can be quantum-coherently controlled in a given nanoscale system, such as charge, spin, mechanical motion and photons. We review the current state of the art and focus on outstanding challenges and opportunities unlocked by the merging of nanoscience and coherent quantum operations.

Abstract:

Resonant optical excitation of certain molecular vibrations in κ−(BEDT−TTF)2Cu[N(CN)2]Br has been shown to induce transient superconductinglike optical properties at temperatures far above equilibrium Tc. Here, we report experiments across the bandwidth-tuned phase diagram of this class of materials, and study the Mott insulator κ−(BEDT−TTF)2Cu[N(CN)2]Cl and the metallic compound κ−(BEDT−TTF)2Cu(NCS)2. We find nonequilibrium photoinduced superconductivity only in κ−(BEDT−TTF)2Cu[N(CN)2]Br, indicating that the proximity to the Mott insulating phase and possibly the presence of preexisting superconducting fluctuations are prerequisites for this effect.