Local Detection of Quantum Correlations and Energy Transport in Trapped Ions
Usually, detection of quantum correlations between two systems requires access to both of those systems. We present a method for detecting correlations between an open quantum system and its environment by acting only locally on the open system and apply it to a single trapped ion, where local system is the electronic state and the environment is the motional states. The method involves removing the correlations with a dephasing operation on the electronic degree-of-freedom using an induced ac-Stark shift. By comparing the subsequent time evolution of the local system with and without the correlations, we are able to witness the correlations of the initial state. We can identify these correlations as quantum discord in the case of mixed states and entanglement for pure states. We explore the dynamics with the increasing size of the environment and relate the results to how energy propagates in ion chains.