Dmytro Dubyna

Observation of Genuine Tripartite Non-Gaussian Entanglement from a Superconducting Three-Photon Spontaneous Parametric Down-Conversion Source

  1. Benjamin Jarvis-Frain,
  2. Andy Schang,
  3. Fernando Quijandría,
  4. Ibrahim Nsanzineza,
  5. Dmytro Dubyna,
  6. C.W. Sandbo Chang,
  7. Franco Nori,
  8. and C.M. Wilson
The generation of entangled photons through Spontaneous Parametric Down-Conversion (SPDC) is a critical resource for many key experiments and technologies in the domain of quantum optics.
Historically, SPDC was limited to the generation of photon pairs. However, the use of the strong nonlinearities in circuit quantum electrodynamics has recently enabled the observation of Three-Photon SPDC (3P-SPDC). Despite great interest in the entanglement structure of the resultant states, entanglement between photon triplets produced by a 3P-SPDC source has still has not been confirmed. Here, we report on the observation of genuine tripartite non-Gaussian entanglement in the steady-state output field of a 3P-SPDC source consisting of a superconducting parametric cavity coupled to a transmission line. We study this non-Gaussian tripartite entanglement using an entanglement witness built from three-mode correlation functions, and observe a maximum violation of the bound by 23 standard deviations of the statistical noise. Furthermore, we find strong agreement between the observed and the analytically predicted scaling of the entanglement witness. We then explore the impact of the temporal function used to define the photon mode on the observed value of the entanglement witness.
arxiv pdf

Cavity quantum electrodynamics with dressed states of a superconducting artificial atom

  1. Yu-Han Chang,
  2. Dmytro Dubyna,
  3. Wei-Chen Chien,
  4. Chien-Han Chen,
  5. Cen-Shawn Wu,
  6. and Watson Kuo
We experimentally studied the microwave response of a transmon artificial atom coupled to two closely spaced resonant modes. When the atom is under driven with one of the modes, the
atom state and mode photons are superposed, forming the dressed states. Dressed states with 1st, 2nd and 3rd excited states of the atom were prepared and probed via the strong coupling to the other resonant mode from the point of view of cavity quantum electrodynamics. The transmission of the probe tone is modulated by the driving microwave amplitude, displaying multi-photon process associated with the inter-atomic level transitions. Our system provides an easy method to study the dressed states by driving one mode and probing the Landau-Zener transition of the other.
arxiv pdf