Grant: Alliance Grants

A cup of hot tea cools down to ambient temperature when you leave it on the table for long enough. A drop of water evaporates into the air when left alone. Any object is connected and influenced by its surroundings. Very tiny objects, for which the physical laws of quantum theory are applicable, are dramatically influenced by minimal interaction with their surroundings. Indeed, merely observing such an object changes its state entirely. The theory which describes the influence of surroundings is called the theory of open quantum systems. This theory is very important because it explains fundamental scientific phenomena. This theory is also crucial to applied modern quantum sciences, in particular in quantum computing and quantum chemistry and biology. An important goal in applications is to take advantage of quantum properties. These properties, such as 'coherence' and 'entanglement', are unique to the quantum world. Nature is taking advantage of them in plants and bacteria, as they are at the root of a dramatic speedup and increased efficiency of chemical processes. In a quantum computer they can be used to radically outperform classical computers. Unfortunately, the degree of quantum behaviour of a system is hampered by the interaction with its surroundings. It is as if shaking a quantum system (effect of the surroundings) would destroy its useful quantum properties. It is plausible that if the surroundings act 'slowly' on the system, which one can quantify by a long 'memory time', then the loss of quantum properties would be slow as well, and one could still exploit the quantumness. In this project, we create and analyze theoretical models describing the loss of quantum properties, and how that loss depends on the memory time of the surroundings. Once this relation is known, one can optimize it and find out how one might influence the surroundings (heat it, cool it, apply a magnetic field...) in order to preserve the system quantum properties for as long as possible. Our work is theoretical, involving analytical and numerical analysis. The hope is that it might eventually become useful in practical, experimental and ultimately industrial applications.