Thomas Aref

Nonexponential decay of a giant artificial atom

  1. Gustav Andersson,
  2. Baladitya Suri,
  3. Lingzhen Guo,
  4. Thomas Aref,
  5. and Per Delsing
In quantum optics, light-matter interaction has conventionally been studied using small atoms interacting with electromagnetic fields with wavelength several orders of magnitude larger
than the atomic dimensions. In contrast, here we experimentally demonstrate the vastly different giant atom regime, where an artificial atom interacts with acoustic fields with wavelength several orders of magnitude smaller than the atomic dimensions. This is achieved by coupling a superconducting qubit to surface acoustic waves at two points with separation on the order of 100 wavelengths. This approach is comparable to controlling the radiation of an atom by attaching it to an antenna. The slow velocity of sound leads to a significant internal time-delay for the field to propagate across the giant atom, giving rise to non-Markovian dynamics. We demonstrate the non-Markovian character of the giant atom in the frequency spectrum as well as nonexponential relaxation in the time domain.
arxiv pdf

Quantum Acoustics with Surface Acoustic Waves

  1. Thomas Aref,
  2. Per Delsing,
  3. Maria K. Ekström,
  4. Anton Frisk Kockum,
  5. Martin V. Gustafsson,
  6. Göran Johansson,
  7. Peter Leek,
  8. Einar Magnusson,
  9. and Riccardo Manenti
It has recently been demonstrated that surface acoustic waves (SAWs) can interact with superconducting qubits at the quantum level. SAW resonators in the GHz frequency range have also
been found to have low loss at temperatures compatible with superconducting quantum circuits. These advances open up new possibilities to use the phonon degree of freedom to carry quantum information. In this paper, we give a description of the basic SAW components needed to develop quantum circuits, where propagating or localized SAW-phonons are used both to study basic physics and to manipulate quantum information. Using phonons instead of photons offers new possibilities which make these quantum acoustic circuits very interesting. We discuss general considerations for SAW experiments at the quantum level and describe experiments both with SAW resonators and with interaction between SAWs and a qubit. We also discuss several potential future developments.
arxiv pdf