Quantum entanglement is the ‘fuel’ that will power future quantum technologies, enabling more secure communications, faster computations, and more precise measurement. As a result, the efficient generation of useful entanglement, its protection from damaging noise, and its exploitation for technological benefit are all topics of intense research. In particular, the generation of “thermally-robust” entanglement would be particularly advantageous, since it would make quantum technologies less susceptible to the detrimental effects of thermal noise and relax the demanding requirement for pure initial state preparation. Arguably, the fragility of entanglement to typical environmental noises sources is the key issue that has hampered the transition of quantum technologies from proof-of-concept lab-based experiments to wide-spread devices of clear practical benefit.
In this project, we consider the thermally-robust generation of entanglement between individual atomic pairs. The entanglement is generated via collisions between the atoms and then preserved by storing the entangled two-atom state in a "decoherence free subspace", a situation where damaging noise has opposite effects on the two atoms leading to no net effect on the pair. Experiments performed in the lab of Mikkel Andersen at the University of Otago have demonstrated long-lived spin correlations between thermal atom pairs in optical microtraps - a necessary (but not sufficient) condition for thermally-robust entanglement.
This project will develop models of spin-exchange collisions between two thermal atoms held in optical tweezers, and use these to theoretically demonstrate that incoherent thermal collisions can entangle two atoms, that the resulting entanglement is robust, and has applications (e.g. magnetometry).