A new paper on the arXiv today. In this work we describe how to make a scalable quantum computer using atomic ensembles – small gas samples, which can be manipulated using laser light. These ensembles make very attractive qubits since you don’t need to be able to address and manipulate single atoms. Instead you have a sample containing perhaps billions of atoms which can be collectively manipulated. They have very long decoherence times. Several experimental groups around the world have already demonstrated simple quantum information processing applications using atomic ensembles. However, none of the experiments to date are scalable, i.e. they cannot, even in principle, be scaled up to make a large quantum computer. In this paper we show to achieve scalability. All of the building blocks in our protocol are experimentally viable using present day technology, so hopefully at some stage in the near future someone will actually be able to demonstrate the elementary components of our protocol.
Rock. I am doing the weekly top ten at the group meeting today. Any paper that begins with the words “Scalable quantum computer” is sure to make it in.
Thanks, Sean, for this and many other lucid explanations.Although I have some phooaslphicil queasiness with the Many Worlds interpretation, my biggest problem is that I haven’t yet seen a convincing demonstration of the core claim: that a large quantum system settles over time into an observer-like portion that looks like a set of noninteracting classical possibilities and an environment-like portion that is correlated with the observer.I’ve seen a few papers claiming to prove this, but they fall into two categories: 1) completely impenetrable, and 2) making dubious assumptions that seem like they might be taking the desired conclusion as an axiom (a typical example is assuming that the observer system is localized in a small region of space).Can anyone recommend a good survey of Many Worlds, Decoherence, etc. at, say, the introductory graduate school level for those of us who are confused?