A quantum logic spectroscopy system for an ion trap configured to trap a primary ion and a detection ion, the quantum logic spectroscopy system configured to apply one or more conditioning operations, each of the one or more conditioning operations comprising applying a mapping operation to map a primary ion state of the primary ion on to a detection ion state of the detection ion, applying a state change operation comprising changing the detection ion state if the detection ion state has a first detection state value, and determine a probability of the detection ion state changing in response to the application of the state change operation, and determine the primary ion state using the determined probability or determine that the primary ion state is indeterminate using the determined probability.