Phys.org December 15, 2022
In previous research, only one waveguide has been coupled to the qubit with limited access to its symmetries. Researchers in Sweden used two waveguides. They demonstrated a novel coupling scheme between an artificial molecule comprising two identical, strongly coupled transmon qubits and two microwave waveguides. The coupling was engineered so that transitions between states of the same symmetry, with respect to the permutation operator, are predominantly coupled to one waveguide. The coupling selectivity exceeded by a factor of 30 for both waveguides in their device. They showed that it can be used to coherently couple states of different symmetry in the single-excitation manifold of the molecule. Using that process, they implemented frequency conversion across the waveguides, mediated by the molecule, with efficiency of about 95%. They also showed that this coupling arrangement made it possible to generate spatially separated Bell states propagating across the waveguides. According to the researchers further applications may include quantum thermodynamics, microwave photodetection, and photon-photon gates… read more. Open Access TECHNICAL ARTICLEÂ
Device architecture and experimental setup…Credit: Phys. Rev. Lett. 129, 123604, 15 September 2022