Experimental demonstration of coherent feedback control on optical field squeezing

Understand

Coherent feedback is a non-measurement based, hence a back-action free, method of control for quantum systems.

• A typical application of this control scheme is squeezing enhancement, a purely non-classical effect in quantum optics.
• In this paper we report its first experimental demonstration that well agrees with the theory taking into account time delays and losses in the coherent feedback loop.
• The results clarify both the benefit and the limitation of coherent feedback control in a practical situation.