Engineering the Frequency Spectrum of Bright Squeezed Vacuum via Group Velocity Dispersion in an SU(1,1) Interferometer

Abstract

Bright squeezed vacuum, a promising tool for quantum information, can be generated by high-gain parametric down-conversion. However, its frequency and angular spectra are typically quite broad, which is undesirable for applications requiring single-mode radiation. We tailor the frequency spectrum of high-gain parametric down-conversion using an SU(1,1) interferometer consisting of two nonlinear crystals with a dispersive medium separating them. The dispersive medium allows us to select a narrow band of the frequency spectrum to be exponentially amplified by high-gain parametric amplification. The frequency spectrum is thereby narrowed from $(56.5\pm 0.1)$ to $(1.22\pm 0.02)\mathrm{THz}$ and, in doing so, the number of frequency modes is reduced from approximately 50 to $1.82\pm 0.02$. Moreover, this method provides control and flexibility over the spectrum of the generated light through the timing of the pump.