Guido Menichetti

Experimental observation of dynamical blockade between transmon qubits via ZZ interaction engineering

  1. Marco Riccardi,
  2. Aviv Glezer Moshe,
  3. Guido Menichetti,
  4. Riccardo Aiudi,
  5. Carlo Cosenza,
  6. Ashkan Abedi,
  7. Roberto Menta,
  8. Halima Giovanna Ahmad,
  9. Diego Nieri Orfatti,
  10. Francesco Cioni,
  11. Davide Massarotti,
  12. Francesco Tafuri,
  13. Vittorio Giovannetti,
  14. Marco Polini,
  15. Francesco Caravelli,
  16. and Daniel Szombati
We report the experimental realization of strong longitudinal (ZZ) coupling between two superconducting transmon qubits achieved solely through capacitive engineering. By systematically
varying the qubit frequency detuning, we measure cross-Kerr inter-qubit interaction strengths ranging from 10 MHz up to 350 MHz, more than an order of magnitude larger than previously observed in similar capacitively coupled systems. In this configuration, the qubits enter a strong-interaction regime in which the excitation of one qubit inhibits that of its neighbor, demonstrating a dynamical blockade mediated entirely by the engineered ZZ coupling. Circuit quantization simulations accurately reproduce the experimental results, while perturbative models confirm the theoretical origin of the energy shift as a hybridization between the computational states and higher-excitation manifolds. We establish a robust and scalable method to access interaction-dominated physics in superconducting circuits, providing a pathway towards solid-state implementations of globally controlled quantum architectures and cooperative many-body dynamics.
arxiv pdf

Overcoming disorder in superconducting globally-driven quantum computing

  1. Riccardo Aiudi,
  2. Julien Despres,
  3. Roberto Menta,
  4. Ashkan Abedi,
  5. Guido Menichetti,
  6. Vittorio Giovannetti,
  7. Marco Polini,
  8. and Francesco Caravelli
We study the impact of static disorder on a globally-controlled superconducting quantum computing architecture based on a quasi-two-dimensional ladder geometry [R. Menta et al., Phys.
Rev. Research 7, L012065 (2025)]. Specifically, we examine how fabrication-induced inhomogeneities in qubit resonant frequencies and coupling strengths affect quantum state propagation and the fidelity of fundamental quantum operations. Using numerical simulations, we quantify the degradation in performance due to disorder and identify single-qubit rotations, two-qubit entangling gates, and quantum information transport as particularly susceptible. To address this challenge, we rely on pulse optimization schemes, and, in particular, on the GRAPE (Gradient Ascent Pulse Engineering) algorithm. Our results demonstrate that, even for realistic levels of disorder, optimized pulse sequences can achieve high-fidelity operations, exceeding 99.9% for the three quantum operations, restoring reliable universal quantum logic and robust information flow. These findings highlight pulse optimization as a powerful strategy to enhance the resilience to disorder of solid-state globally-driven quantum computing platforms.
arxiv pdf