The full blossoming of quantum technologies requires the availability of easy-to-prepare materials where quantum coherences can be effectively initiated, controlled, and exploited, preferably at ambient conditions. Solid-state multilayers of colloidally grown quantum dots (QDs) are highly promising for this task because of the possibility of assembling networks of electronically coupled QDs through the modulation of sizes, inter-dot linkers, and distances. To usefully probe coherence in these materials, the dynamical characterization of their collective quantum mechanically coupled states is needed. Here, we explore by two-dimensional electronic spectroscopy the coherent dynamics of solid-state multilayers of electronically coupled colloidally grown CdSe QDs and complement it by detailed computations. The time evolution of a coherent superposition of states delocalized over more than one QD was captured at ambient conditions. We thus provide important evidence for inter-dot coherences in such solid-state materials, opening up new avenues for the effective application of these materials in quantum technologies.

One of the most recent developments at the forefront of nanotechnology is the attempt to exploit quantum phenomena in nanometer scale materials, exploring novel applications of quantum effects. An effective exploitation of quantum phenomena must necessarily pass through a deep understanding of how to generate, manipulate, and characterize coherent superposition of quantum states in the nanosystems. However, despite the lively interest in this topic, the study of coherent effects in nanomaterials still represents relatively unexplored territory. Here we report an investigation on the ultrafast coherent dynamics of colloidal CdSe quantum dots (QDs) by the mean of two-dimensional electronic spectroscopy (2DES). The time evolution of specific coherent superpositions of fine structure levels in these nanomaterials is clearly demonstrated. The obtained results represent an important step forward toward a deeper understanding of quantum properties of nanomaterials.

We present a quantum-chemical investigation of the excited states of the complex [Re(CO)(Im)(Phen)] (Im = imidazole; Phen = 1,10-phenanthroline) in solution including spin-orbit couplings and vibrational sampling. To this aim, we implemented electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) in the Amsterdam Density Functional program suite, suitable for time-dependent density functional calculations including spin-orbit couplings. The new implementation is employed to simulate the absorption spectrum of the complex, which is compared to the results of implicit continuum solvation and frozen-density embedding. Molecular dynamics simulations are used to sample the ground state conformations in solution. The results demonstrate that any study of the excited states of [Re(CO)(Im)(Phen)] in solution and their dynamics should include extensive sampling of vibrational motion and spin-orbit couplings.