Erlangen 2022 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 12: Quantum Optics (Miscellaneous) II

Q 12.4: Talk

Monday, March 14, 2022, 17:15–17:30, Q-H14

A stepwise approach to the BSV description — •Dennis Scharwald and Polina Sharapova — Paderborn University, Department of Physics, Warburger Str. 100, D-33098 Paderborn, Germany

The bright squeezed vacuum state of light (BSV) is a macroscopic state generated by unseeded parametric down-conversion (PDC). Its large photon number and strong correlations between the signal and idler photons make it an interesting candidate for applications and theoretical investigations. One of the prominent theoretical frameworks for the BSV description is the “regular” Schmidt-mode theory, which describes the BSV in terms of Schmidt modes. This provides a fully analytical description but fails to explain the broadening of the itensity spectrum with increasing gain [1]. Another purely numerical approach involves the solution of integro-differential equations in order to obtain the output state of the PDC section [2]. This approach is in good agreement with the experiment even with increasing gain.

In our work, we combine both approaches by splitting the PDC section into small segments which are connected via the input/output relations for the plane-wave operators. As a result, we can observe the evolution of the Schmidt-modes as they propagate through a nonlinear crystal, as well as the broadening in the intensity spectrum which matches the prediction of the integro-differential equation method and the experimental results.

[1] P. Sharapova et al., Phys. Rev. A 91, 043816 (2015)
[2] P. R. Sharapova et al., Phys. Rev. Research 2, 013371 (2020)