Entangled states are a key resource in fundamental quantum physics, quantum cryptography, and quantum computation . To date, controlled unitary interactions applied to a quantum system, so-called "quantum gates'', have been the most widely used method to deterministically create entanglement . These processes require minimal decoherence that inevitably arises from coupling of the system to the environment and imperfect control of the system parameters. Here, on the contrary, we combine unitary processes with engineered dissipation to deterministically produce and stabilize a Bell state of two trapped ions independent of their initial state. This strategy was also demonstrated in  but in contrast to that work, here we do not employ standard entangling gates and we implement the process in a continuous or near-continuous fashion to achieve steady state entanglement, analogous to optical pumping of atomic states. Engineered coupling to the environment can be applied to a broad range of experimental systems to achieve desired quantum dynamics or steady states. Indeed, concurrently with this work, a maximally entangled steady state of two superconducting qubits was demonstrated using dissipation .
Pub Type: Journals
Entanglement, Quantum Information, Trapped Ions