Experimental quantum state engineering with time-separated heraldings from a continuous-wave light source: A temporal-mode analysis

Conditional preparation is a well-established technique for quantum state engineering of light. A general trend is to increase the number of heralding detection events in such a realization to reach larger photon-number states or their arbitrary superpositions. In contrast to pulsed implementations, where detections only occur within the pulse window, for continuous-wave light the temporal separation of the conditioning detections is an additional degree of freedom and a critical parameter. Based on a theoretical study by Nielsen and Mølmer [A. E. B. Nielsen and K. Mølmer, Phys. Rev. A 75, 043801 (2007)]PLRAAN1050-294710.1103/PhysRevA.75.043801 and on a continuous-wave two-mode squeezed vacuum from a nondegenerate optical parametric oscillator, we experimentally investigate the generation of two-photon state with tunable delay between the heralding events. The present work illustrates the temporal multimode features in play for conditional state generation based on continuous-wave light sources and quantifies the compromise between preparation rate and fidelity in this scenario.