Scalable entanglement stabilization with modular reservoir engineering

Abstract: Dissipation engineering is a powerful framework for quantum state preparation and autonomous error correction in few-qubit systems. In this work, we examine the scalability of this approach and give three criteria which any dissipative state stabilization protocol should satisfy to be truly scalable as the number of qubits grows. Besides the requirement that it can be constructed in a resource-efficient manner from simple-to-engineer building blocks, a scalable protocol must also exhibit favorable scaling of the stabilization time with the increase in system size. We present a family of protocols which employ fixed-depth qubit-qubit interactions alongside engineered linear dissipation to stabilize an $N$-qubit W state. We find that a modular approach to dissipation engineering, with several overlapping few-qubit dissipators rather than a single $N$-qubit dissipator, is essential for our protocol to be scalable. With this approach, as the number of qubits increases our protocol exhibits low-degree polynomial scaling of the stabilization time and linear growth of the number of control drives in the best case. While the proposed protocol is most easily accessible with current state-of-the-art circuit-QED architectures, the modular dissipation engineering approach presented here can be readily adapted to other platforms and for stabilization of other interesting quantum states.