The Entanglement Frontier

Information encoded in quantum systems is different than information expressed in terms of ordinary classical bits. For example, if you read ten pages of an ordinary hundred-page book, you learn about 10% of the content of the book. But if you read ten pages of a hundred-page quantum book, you learn almost nothing about the content of the book. That's because nearly all the information in a quantum book is encoded in the correlations among the pages; you can't access it if you read the book one page at a time. This unusual feature of quantum information is called "quantum entanglement," and it is the reason we expect large-scale quantum computers to be more powerful than ordinary digital computers. I will discuss why the quest for precisely controllable highly entangled quantum systems is important, and also why it is very difficult.