Preparing pure states with lossy beam splitters using quantum coherent absorption of squeezed light
Martijn Wubs, Ali Ü. C. Hardal · 2019
We investigate coherent perfect absorption (CPA) of squeezed coherent states of light by an absorbing beam splitter. First we derive the absorption coefficients for quantum coherence and for intensity, which generally differ. Secondly, we present the remarkable properties of a CPA-gate: two identical but otherwise arbitrary incoming squeezed coherent states can be completely stripped off their coherence, producing a pure entangled squeezed vacuum state at the output. Importantly, this output state of light is not entangled with the absorbing beam splitter by which it was produced. This makes the CPA gate potentially interesting for continuous-variable quantum state preparation.