Dephasing for Good: Optimal Decoherence for Efficient Light Harvesting and Sensing

Waves acting in phase interfere. In the micro world, quantum interference strongly influences material properties. We will investigate such quantum materials including arrays of nanocrystals and nanowires.

The components of such arrays can act in phase, leading to collective phenomena where the action scales faster than the size of the system.

Clearly, such superlinear scaling must have a limit – beyond a certain length scale, the phase-relation will deteriorate due to decoherence effects.

Intuitively, one may think that such decoherence/dephasing is always detrimental for any quantum technology but for most of the tasks world without friction would not work – for many quantum applications there exists an optimal level of decoherence leading to the most efficient function.

Finding principles and mechanisms of optimal dephasing and how to control it, is the central task of the current proposal.We will use delocalization as a sensitive decoherence witness in coherent spectroscopies.

The influence of decoherence on long-distance energy and charge carrier transport in nanomaterials will be investigated at operational conditions. In this way, we will perform a “touch” of quantum dynamics, relevant to the functioning of light-harvesting.

Since we will study the spatial extent and dynamics of excitation delocalization with simultaneously high time and energy resolution beyond the usual Fourier limit, we will obtain a new look at optimal transport in time, energy and space.