Welcome to the Research Group Hybrid Quantum Systems
Quantum emitters are nanometer-scale objects, such as molecules or atoms, that absorb and re-emit light. Despite their small size, they can be reliably detected under a microscope thanks to their fluorescence emission. Furthermore, their optical properties, such as the wavelength of the emitted light, depend on their immediate surroundings: temperature, pressure, and electric fields all measurably alter the behavior of a single emitter. Therefore, the quantum emitters can serve as an optical “bridge”, making it possible to study and affect their nano-environment using light.
In our research group “Hybrid Quantum Systems”, we use organic dye molecules as single quantum emitters. We embed them in crystalline solids, such as anthracene and naphthalene, and cool them down to cryogenic temperatures. Under these conditions, their exact wavelengths can be determined with very high accuracy, turning them into precision sensors of their immediate surrounds. At the same time, their small size enables us to achieve a spatial resolution in the nanometer range, which surpasses traditional optical methods by a factor of ten to a hundred. Importantly, the interaction between the emitter and its environment proceeds in both directions with emitters reporting on their surroundings whilst also generating local changes in temperature or pressure when stimulated by light. Measurement and manipulation on the nanoscale thus intertwine. We investigate the physics of this coupling and use it to develop approaches for novel quantum systems.
Our Projects
Hybrid molecular optomechanical systems
Quantum emitters can be functionally enhanced by coupling them to excitations in their environment. One such excitation is localized high-frequency mechanical vibrations – trapped sound waves. To engineer this coupling, we create nanocrystals doped with single organic dye molecules serving as quantum emitters. The strain created by localized vibrations in such a system distorts the molecules and changes their transition frequencies. A kind of optomechanical coupling arises: the molecules can act as an optical interface for the local high-frequency vibrations in the crystal. Due to the laws of quantum mechanics, this coupling is bidirectional – it can be used both to detect and to excite the mechanical vibrations. This opens up two possibilities: The mechanical modes can serve as a shared medium that connects several molecules, or as a quantum memory that expands the utility of single molecules as quantum technology building blocks.
Sensing heat on the nanoscale
Heat generation and propagation at low temperatures and the nanometer scale differ significantly from standard thermal transport, as the quantum and wave nature of the heat carriers, phonons, must be taken into account. A deeper understanding of this regime is relevant to the design of cryogenic microscopic optical and microwave devices such as superconducting qubits, in which uncontrolled heating often limits performance. Until now, it has not been possible to map experimentally how temperature is spatially distributed around a point heat source in this regime. To address this, we use molecules both as point heat sources and as optical cryogenic temperature sensors. Through a combination of sensitive optical intensity measurements and subdiffraction localization, we achieve millikelvin temperature sensitivity and nanometer spatial resolution. This allows us to image temperature very close to the heat source, shedding light on the behavior of phonons in these unusual circumstances.
Contact
Research Group Alexey Shkarin
Max Planck Institute for the Science of Light
Staudtstr. 2
91058 Erlangen, Germany
+49 9131 7133 323
Research team leader Dr. Alexey Shkarin
