Demonstration of Heralded Optical Attenuation by Zero Photon Subtraction

Photon subtraction is widely employed for optical quantum state engineering with potential applications in quantum communication, and it can be accomplished by conditional measurements of single photons at the outputs of a beam splitter. Interestingly, conditioning on the detection of zero photons in a similar way also transforms optical states. In particular, this so-called "zero photon subtraction" reduces the mean photon number of any superposition of Fock states. Here we experimentally demonstrate this counterintuitive type of attenuation and observe an interesting dependence on the photon number statistics of the input state. These effects are analogous to that of typical single-photon subtraction and provide some additional insight into physical implementations of creation and annihilation operators in quantum optics.