Quantum Optics Laboratory

Abstract: 

Quantum nondemolition measurements are a critical element of feedback-based quantum error correction, as well as a powerful building block in more general quantum information processing and metrology protocols. Trapped ions are one of the most promising technologies for realising quantum information processing and quantum simulation. We have used beryllium and calcium ions to implement the basic toolbox for quantum information processing. Additionally, we have carried  out a nondemolition parity measurement of two beryllium ions via a calcium ion in the same trap, relying on mixed-species entangling gates and local operations implemented using global laser beams. We have characterized the operation of the technique by preparing the beryllium ions in a range of Bell states. Our work offers several advantages over standard methods as hybrid trapped-ion quantum information processing systems grow in complexity.