Hollow-core photonic crystal fiber source for very bright twin beams

03.02.2016, 13:00

Copyright: MPL

Quantum optical experiments rely critically on well-designed sources for correlated photons and twin beams. The number of available sources is however very limited. While most experiments use crystal-based parametric down conversion, there is increasing interest in fiber-based systems, which have the advantages of a well-defined spatial mode as well as wide flexibility in the design of the temporal mode structure. The photon-number correlations in such systems are however corrupted by an inelastic light-scattering process, inherent to any molecular system: Raman scattering. We have recently demonstrated a novel source of twin-beams based on a noble-gas-filled hollow-core photonic crystal fiber. The nonlinearity in this system is provided by high-pressure argon gas, which intrinsically prevents deleterious Raman scattering. The source allows the central twin-beam frequencies to be pressure-tuned over 80 THz-something that is impossible in standard solid-core fiber sources. The flat dispersion of the waveguide leads to an exceptionally broad twin beam spectrum of ~50 THz, with less than 5 temporal modes. We observe twin-beam squeezing of up to 35% below the shot-noise level, for beams with brightness up to 2500 photons per mode. By eliminating Raman scattering, this system overcomes a central problem of fiber-based twin-beam sources and opens up new possibilities for applications in quantum metrology and quantum key distribution.

Contact: Martin Finger
Group: Russell Division
Reference:M. Finger et al., Phys. Rev. Lett. 115, 143602, 2015.
DOI: http://dx.doi.org/10.1103/PhysRevLett.115.143602