Generation of optical coherent-state superpositions by number-resolved photon subtraction from the squeezed vacuum

We have created heralded coherent-state superpositions (CSSs) by subtracting up to three photons from a pulse of squeezed vacuum light. To produce such CSSs at a sufficient rate, we used our high-efficiency photon-number-resolving transition edge sensor to detect the subtracted photons. This experiment is enabled by and utilizes the full photon-number-resolving capabilities of this detector. The CSS produced by three-photon subtraction had a mean-photon number of $2.{75}_{\ensuremath{-}0.24}^{+0.06}$ and a fidelity of $0.{59}_{\ensuremath{-}0.14}^{+0.04}$ with an ideal CSS. This confirms that subtracting more photons results in higher-amplitude CSSs.