Observation of Co-tunneling in Pairs of Coupled Flux Qubits

We report measurements of macroscopic resonant tunneling between the two lowest energy states of a pair of magnetically coupled rf-SQUID flux qubits. This technique provides a direct means of observing two-qubit dynamics and a probe of the environment coupled to the pair of qubits. Measurements of the tunneling rate as a function of qubit flux bias show a Gaussian line shape that is well matched to theoretical predictions. Moreover, the peak widths indicate that each qubit is coupled to a local environment whose fluctuations are uncorrelated with that of the other qubit.

Here’s the arxiv link: arXiv:1006.0028

3 thoughts on “Observation of Co-tunneling in Pairs of Coupled Flux Qubits

  1. You’re right Miles, this post deserves more comments. My comment will be : I generally find that posts about scientific results get less commentary than by-the-by blog posts.

    Personally I would find it interesting if skeptics/scientists commented about the papers here. Maybe whether some questions were answered, or if others were raised… Maybe that’s what arxiv needs: a comments thread for each of the papers…

    • Murray,
      “Maybe that’s what arxiv needs: a comments thread for each of the papers” is a nice idea. I could imagine that paper authors wouldn’t like this since it would generate content on their papers was more informal. I’m guessing they would want more effort for any comment like the current process of drafting and uploading comment papers. So, it may be a while before arxiv provides a discussion forum. That said, a phrase I use here only to annoy you Murray ;p , a forum hosted on a seperate website to discuss papers would work and in our Pank Rank driven world would aid searching.

      BTW what about a more Web 2.0 approach in which readers tag paper, or paper-versions? This would aid searching and provide a light level of feedback that is unordered, aggregatable and easier to make multi-lingual. Hmmm.

  2. Comment on the paper itself. It is highly significant b/c it shows persistent currents and qubit tunneling energies can be sync’ed across two devices. As well, here the noise is local to each qubit. If this result can be maintained as systems are “scaled” that is great news. Finally, a single qubit can be probed without the need for individual microwave. Something I can appreciate but don’t fully understand. I like the paper b/c it has some seriusly good looking data. Strictly an esthetic observation.

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