E. Solano

Photon transfer in ultrastrongly coupled three-cavity arrays

  1. S. Felicetti,
  2. G. Romero,
  3. D. Rossini,
  4. R. Fazio,
  5. and E. Solano
We study the photon transfer along a linear array of three coupled cavities where the central one contains an interacting two-level system in the strong and ultrastrong coupling regimes.
We find that an inhomogeneously coupled array forbids a complete single-photon transfer between the external cavities when the central one performs a Jaynes-Cummings dynamics. This is not the case in the ultrastrong coupling regime, where the system exhibits singularities in the photon transfer time as a function of the cavity-qubit coupling strength. Our model can be implemented within the state-of-the-art circuit quantum electrodynamics technology and it represents a building block for studying photon state transfer through scalable cavity arrays.
arxiv pdf

Fast microwave beam splitters from superconducting resonators

  1. M. Haeberlein,
  2. D. Zueco,
  3. P. Assum,
  4. T. Weißl,
  5. E. Hoffmann,
  6. B. Peropadre,
  7. J.J. Garcia-Ripoll,
  8. E. Solano,
  9. F. Deppe,
  10. A. Marx,
  11. and R. Gross
Coupled superconducting transmission line resonators have applications in quantum information processing and fundamental quantum mechanics. A particular example is the realization of
fast beam splitters, which however is hampered by two-mode squeezer terms. Here, we experimentally study superconducting microstrip resonators which are coupled over one third of their length. By varying the position of this coupling region we can tune the strength of the two-mode squeezer coupling from 2.4% to 12.9% of the resonance frequency of 5.44GHz. Nevertheless, the beam splitter coupling rate for maximally suppressed two-mode squeezing is 810MHz, enabling the construction of a fast and pure beam splitter.
arxiv pdf

Quantum Simulations of Relativistic Quantum Physics in Circuit QED

  1. J. S. Pedernales,
  2. R. Di Candia,
  3. D. Ballester,
  4. and E. Solano
We present a scheme for simulating relativistic quantum physics in circuit quantum electrodynamics. By using three classical microwave drives, we show that a superconducting qubit strongly-coupled
to a resonator field mode can be used to simulate the dynamics of the Dirac equation and Klein paradox in all regimes. Using the same setup we also propose the implementation of the Foldy-Wouthuysen canonical transformation, after which the time derivative of the position operator becomes a constant of the motion.
arxiv pdf

Path Entanglement of Continuous-Variable Quantum Microwaves

  1. E. P. Menzel,
  2. R. Di Candia,
  3. F. Deppe,
  4. P. Eder,
  5. L. Zhong,
  6. M. Ihmig,
  7. M. Haeberlein,
  8. A. Baust,
  9. E. Hoffmann,
  10. D. Ballester,
  11. K. Inomata,
  12. T. Yamamoto,
  13. Y. Nakamura,
  14. E. Solano,
  15. A. Marx,
  16. and R. Gross
Path entanglement constitutes an essential resource in quantum information and communication protocols. Here, we demonstrate frequency-degenerate entanglement between continuous-variable
quantum microwaves propagating along two spatially separated paths. We combine a squeezed and a vacuum state using a microwave beam splitter. Via correlation measurements, we detect and quantify the path entanglement contained in the beam splitter output state. Our experiments open the avenue to quantum teleportation, quantum communication, or quantum radar with continuous variables at microwave frequencies.
arxiv pdf

Circuit Quantum Electrodynamics with a Superconducting Quantum Point Contact

  1. G. Romero,
  2. I. Lizuain,
  3. V. S. Shumeiko,
  4. E. Solano,
  5. and F. S. Bergeret
We consider a superconducting quantum point contact in a circuit quantum electrodynamics setup. We study three different configurations, attainable with current technology, where a
quantum point contact is coupled galvanically to a coplanar waveguide resonator. Furthermore, we demonstrate that the strong and ultrastrong coupling regimes can be achieved with realistic parameters, allowing the coherent exchange between a superconducting quantum point contact and a quantized intracavity field.
arxiv pdf