Lattice gauge fields via modulation in circuit QED: The bosonic Creutz ladder

  1. Hadiseh Alaeian,
  2. Chung Wai Sandbo Chang,
  3. Mehran Vahdani Moghaddam,
  4. Christopher M. Wilson,
  5. Enrique Solano,
  6. and Enrique Rico
In this work we propose two protocols to make an effective gauge potential for microwave photons in circuit QED. The schemes consist of coupled transmons whose flux are harmonically
modulated in time. We investigate the effect of various types of capacitive and inductive couplings, and the role of the fixed phase offset of each site on the complex coupling rate between coupled qubits. These configurations can be directly realised in a superconducting circuit and is easily extendable to a scalable lattice. Due to the intrinsic non-linearity of the transmon qubits such lattices would be an ideal platform for simulating Bose-Hubbard Hamiltonians with non-trivial gauge fields.

Entanglement of superconducting qubits via acceleration radiation

  1. Laura García-Álvarez,
  2. Simone Felicetti,
  3. Enrique Rico,
  4. Enrique Solano,
  5. and Carlos Sabín
We show that simulated relativistic motion can generate entanglement between artificial atoms and protect them from spontaneous emission. We consider a pair of superconducting qubits
coupled to a resonator mode, where the modulation of the coupling strength can mimic the harmonic motion of the qubits at relativistic speeds, generating acceleration radiation. We find the optimal feasible conditions for generating a stationary entangled state between the qubits when they are initially prepared in their ground state. Furthermore, we analyze the effects of motion on the probability of spontaneous emission in the standard scenarios of single-atom and two-atom superradiance, where one or two excitations are initially present. Finally, we show that relativistic motion induces sub-radiance and can generate a Zeno-like effect, preserving the excitations from radiative decay.