Rosario Lo Franco

Josephson Travelling Wave Parametric Amplifiers as Non-Classical Light Source for Microwave Quantum Illumination

  1. Luca Fasolo,
  2. Angelo Greco,
  3. Emanuele Enrico,
  4. Fabrizio Illuminati,
  5. Rosario Lo Franco,
  6. David Vitali,
  7. and Patrizia Livreri
Detection of low-reflectivity objects can be enriched via the so-called quantum illumination procedure. In order that this quantum procedure outperforms classical detection protocols,
entangled states of microwave radiation are initially required. In this paper, we discuss the role of Josephson Traveling Wave Parametric Amplifiers (JTWPAs), based on circuit-QED components, as suitable sources of a two-mode squeezed vacuum state, a special signal-idler entangled state. The obtained wide bandwidth makes the JTWPA an ideal candidate for generating quantum radiation in quantum metrology and information processing applications.
arxiv pdf

Entanglement dynamics in superconducting qubits affected by local bistable impurities

  1. Rosario Lo Franco,
  2. Antonio D'Arrigo,
  3. Giuseppe Falci,
  4. Giuseppe Compagno,
  5. and Elisabetta Paladino
We study the entanglement dynamics for two independent superconducting qubits each affected by a bistable impurity generating random telegraph noise (RTN) at pure dephasing. The relevant
parameter is the ratio g between qubit-RTN coupling strength and RTN switching rate, that captures the physics of the crossover between Markovian and non-Markovian features of the dynamics. For identical qubit-RTN subsystems, a threshold value gth of the crossover parameter separates exponential decay and onset of revivals; different qualitative behaviors also show up by changing the initial conditions of the RTN. We moreover show that, for different qubit-RTN subsystems, when both qubits are very strongly coupled to the RTN an increase in entanglement revival amplitude may occur during the dynamics.
arxiv pdf