Tunneling spectroscopy using a probe qubit

New paper published in Phys Rev B last week showing a very cool new technique for examining quantum effects in big quantum systems. Here’s the arxiv link.

Here is the abstract:

We describe a quantum tunneling spectroscopy technique that requires only low bandwidth control. The method involves coupling a probe qubit to the system under study to create a localized probe state. The energy of the probe state is then scanned with respect to the unperturbed energy levels of the probed system. Incoherent tunneling transitions that flip the state of the probe qubit occur when the energy bias of the probe is close to an eigenenergy of the probed system. Monitoring these transitions allows the reconstruction of the probed system eigenspectrum. We demonstrate this method on an rf SQUID flux qubit.

3 thoughts on “Tunneling spectroscopy using a probe qubit

  1. Question–
    Does this have a direct bearing on D-Wave’s method of computing?-Or-Does it provide more of a ‘proof of concept’ regarding producing quantum effects in general?

  2. Hi! The technique was developed to help characterize what’s going on in our processors — not to produce quantum effects, but to measure them. Measurement of properties of large-scale quantum systems is quite difficult, this is a new way to do some of that. It was specifically developed to measure things like entanglement. Currently that technique is being applied to look deep into the quantum mechanics of what happens when one of our processors is solving a problem. The technique is quite powerful and the results are fascinating. We’re going to submit a paper showing a really cool series of experiments looking at entanglement during computation shortly, this technique plays a key role.

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