W.-J. Lin

Deterministic loading and phase shaping of microwaves onto a single artificial atom

  1. W.-J. Lin,
  2. Y. Lu,
  3. P. Y. Wen,
  4. Y.-T. Cheng,
  5. C.-P. Lee,
  6. K.-T. Lin,
  7. K.-H. Chiang,
  8. M. C. Hsieh,
  9. J. C. Chen,
  10. C.-S. Chuu,
  11. F. Nori,
  12. A. F. Kockum,
  13. G.-D. Lin,
  14. P. Delsing,
  15. and I.-C. Hoi
Loading quantum information deterministically onto a quantum node is an important step towards a quantum network. Here, we demonstrate that coherent-state microwave photons, with anoptimal temporal waveform, can be efficiently loaded onto a single superconducting artificial atom in a semi-infinite one-dimensional (1D) transmission-line waveguide. Using a weak coherent state (average photon number N<<1 with an exponentially rising waveform, whose time constant matches the decoherence time of the artificial atom, we demonstrate a loading efficiency of above 94% from 1D semi-free space to the artificial atom. We also show that Fock-state microwave photons can be deterministically loaded with an efficiency of 98.5%. We further manipulate the phase of the coherent state exciting the atom, enabling coherent control of the loading process. Our results open up promising applications in realizing quantum networks based on waveguide quantum electrodynamics (QED).[/expand]
arxiv pdf

Mirror, mirror: Landau-Zener-Stuckelberg-Majorana interferometry of a superconducting qubit in front of a mirror

  1. P. Y. Wen,
  2. O. V. Ivakhnenko,
  3. M. A. Nakonechnyi,
  4. B. Suri,
  5. J.-J. Lin,
  6. W.-J. Lin,
  7. J. C. Chen,
  8. S. N. Shevchenko,
  9. Franco Nori,
  10. and I.-C. Hoi
We investigate the Landau-Zener-Stuckelberg-Majorana interferometry of a superconducting qubit in a semi-infinite transmission line terminated by a mirror. The transmon-type qubit is
at the node of the resonant electromagnetic (EM) field, hiding from the EM field. „Mirror, mirror“ briefly describes this system, because the qubit acts as another mirror. We modulate the resonant frequency of the qubit by applying a sinusoidal flux pump. We probe the spectroscopy by measuring the reflection coefficient of a weak probe in the system. Remarkable interference patterns emerge in the spectrum, which can be interpreted as multi-photon resonances in the dressed qubit. Our calculations agree well with the experiments.
arxiv pdf