Most efforts in the fabrication of platforms for quantum information tasks have been mostly directed towards the increase of the number of units under control, their addressability and the achievement of strong coupling among their units in order to reach fast enough gates and operations within the coherence time. Decoherence from external noise has been fought against by better cooling methods, by dynamical decoupling techniques and by ever more perfected fabrication procedures. Methods of this kind have arguably reached their limits of improvement and new proposals need to appear if we are to harness the much promised advantages that quantum processing will unleash. Our approach will be two-fold: probe/study the characteristics of noise in a relevant platform and benchmark strategies to protect from it.
We propose to use functional embeddings for the protection of quantum information and energy, where the embedding serves as a filter for external noise, but is also an active player in the development of quantum coherence. In particular it is expected to be able to profit from protected frequency/momentum windows due to static features like for example engineered band-gaps, or from multi-scale embeddings (which filter the influence of external noise differently for different wavelengths due to renormalization effects). We will investigate the paradigm of noiseless paths inside vibrational scaffoldings, trying to inspire our research from naturally existing compounds such as, but not limited to, those found in the protein structures surrounding light-harvesting chromophores. At the same time, the microscopic origin of noise in experimental setups is sometimes poorly understood. An example is ions traps where diffusion, or phonon-induced fluctuation, of atoms adsorbed on electrodes, which act as noisy dipoles, are the two most plausible candidates for motional heating. We propose here to study two experimental configurations, based on the manipulation of a pair of trapped ions, where distance/frequency scalings can in principle discriminate between the two, and at the same time reach the unexplored regime
of correlated noise.
Finally, using the ideas from the theoretical study of structured embeddings we expect to propose designs of phonon-bandgapped electrodes such that adatom dipole fluctuations are strongly suppressed, in particular by multiple-layered designs or electrodes with modulated surfaces. Such designs could also help to experimentally discriminate the two kind of noises, by comparing heating in traps with and without phonon-bandgap. The project, of theoretical character but with a marked target towards applications, is divided in three main tasks: the creation of protection strategies through structures, the discrimination of the key noise source in ion traps, and the application of protection concepts for electrodes in traps.