Fundamental Limits of Practical Quantum Technology

Quantum technologies such as quantum computing have the potential of revolutionizing our lives. However, the inherent susceptibility of quantum systems to errors and noise effects in practical scenarios poses serious challenges to the implementation of quantum technologies. To put the theoretically blueprinted quantum advantages into use, scientists have devoted significant efforts to developing better and better methods for battling with noise. But meanwhile, our understanding about the theoretical limits to the performance of such methods under practical constraints, which may determine the ultimate efficiency of quantum technologies, is very limited.

Our work No-Go Theorems for Quantum Resource Purification addresses this urgent and fundamental issue, by mathematically proving a series of universal limits on the accuracy and efficiency of purifying all kinds of noisy quantum “resources” (such as quantum entanglement) that emerge from practical restrictions and play indispensable roles in all kinds of quantum technologies. Remarkably, these theorems allow us to establish the first rigorous understanding of the necessary resource costs of large-scale quantum computing. Our results represent advances on important practical problems as well as theoretical ones — they do not only shed light on the price of quantum technologies in a timely manner, but also push forward our understanding of the fundamental principles of quantum mechanics.