Detection of virtual photons in ultrastrongly coupled quantum systems
Light-matter interaction,and understanding of the fundamental physics behind it,is the scenario of emerging quantum technologies.Solid state devices may ex- plore new regimes where coupling strengths are”ultrastrong”,i.e.comparable to the energies of the subsystems.New exotic phenomena occur as the entangled vacuum contains virtual photons.Despite more than a decade of research,the detection of ground-state virtual photons still awaits demonstration.In this work,we provide a solution for this long-standing problem.We find a design of a super- conducting quantum circuit and a protocol of coherent amplification yielding
a highly efficient,faithful and selective conversion of virtual photons of a ”false”
ground state[2,3] to real ones enabling their detection with state-of-the-art quan-
tum hardware.Supplemented by advanced control,our multilevel design can be
exploited for further quantum tasks in the USC regime. P.Forn-Diaz,et al.,RMP
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