Fig. 2
From: Fiber-coupled EPR-state generation using a single temporally multiplexed squeezed light source
Schematics of the experiment. Bright amplitude squeezed states of light are generated using type-0 parametric down-conversion in an optical resonator (OPO) at the wavelength of 1550 nm, seeded with a coherent beam for phase locks. The squeezed states of light are coupled into a single mode fiber network (marked by blue lines) in which the generation of two-mode squeezing takes place: Using a fiber switch, two consecutive temporal modes (marked by green and purple) are guided in different directions. Subsequently, the two modes are synchronized by a fiber delay of 200 m in one of the modes. Finally, the two spatial modes interfere in a 50:50 fiber coupler, thereby forming a two-mode squeezed state in the output as the phase difference of the two input modes are locked to π/2 (using active feedback to a fiber-stretching device described in Methods). The quadratures of the two-mode squeezed state are measured with two fiber-based homodyne detection stations, Alice and Bob. A typical measurement output in time-domain is shown in the inset together with illustrations of the corresponding states in phase space, alternating between two-mode squeezed states and vacuum states
