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

TL;DR

This paper demonstrates a method to narrow the frequency spectrum of bright squeezed vacuum generated by high-gain parametric down-conversion using an SU(1,1) interferometer with a dispersive medium, enhancing single-mode applicability.

Contribution

The authors introduce a novel spectral engineering technique employing an SU(1,1) interferometer with a dispersive medium to control and narrow the frequency spectrum of bright squeezed vacuum.

Findings

Narrowed the spectrum from 56.5 THz to 1.22 THz

Reduced the number of frequency modes from ~50 to 1.82

Achieved control over the spectrum via pump timing

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 +- 0.1) to (1.22 +- 0.02) THz and, in doing so, the number of frequency modes is reduced from approximately 50 to 1.82 +- 0.02. Moreover, this method provides control and flexibility over the spectrum of the generated light through the timing of the pump.