Figure 1
From: Quantum illumination reveals phase-shift inducing cloaking
Pictorial diagram of the quantum protocol for the detection of cloaked targets. (a) A two-mode squeezed state is generated in the lab. The idler beam stays in a controlled transmission line while the signal is emitted toward a highly reflective background, η ≈ 1, where is mixed with thermal noise. When the signal comes back, it either can be directly received by the measurement device (b) or it can pass before through a metamaterial-cloak which covers a target we want to detect (c) In the latter case, a phase shift is introduced due to the imperfection in current cloaking elements. In any case, a bipartite operation is performed with a Josephson mixer onto the signal and idler beams. Finally the number of photons in the idler beam is measured, which gives the information about the presence of the cloaked object with a gain up to 3 dB over the classical protocol.
