Entanglement in optical parametric down-conversion with losses and noise

A. Gatti, E. Brambilla, Ottavia Jedrkiewicz +1 more

Yousef K. Chahine, Evan J. Katz, Adam Fallon +1 more

We present several techniques for high-rate entanglement generation through heralded, multiplexed parametric down-conversion (PDC), generalizing previous cascaded PDC and zero-added-loss multiplexing (ZALM) schemes. Closed form expressions for the heralding rate and fidelity extend previous analyses.

Roman V. Zakharov, Olga V. Tikhonova

Vladimir V. Kornienko, Semyon Germanskiy, G. Kh. Kitaeva +1 more

We examine the features of parametric down-conversion for generating non-classical optical-terahertz biphoton fields. The calculations were performed for a second-order correlation function and noise reduction factor (NRF), which were selected as measures of non-classicality of the field states. NRF measurement schemes were found to be less advantageous. Overall system temperature at which non-classical effects are still observable has been estimated as about 10 K. The priority of the main complicating factors for the quantum-optical measurements in the terahertz range has been determined. Thus, the most important parameter is the temperature of the system, after that come the absorption losses at terahertz frequencies, and the parametric conversion efficiency has the lowest impact. Increasing the pump radiation power has been found to be inefficient for "noise" suppression in this case. The calculations performed were based on lithium niobate dispersion properties due to its outstanding nonlinear optical properties and because it is frequently used for optical-to-terahertz frequency conversion.

Yen-Ju Chen, Chun-Yuan Cheng, Tien-Dat Pham +4 more

Quantum fluctuation plays a key role in the parametric down-conversion in the Langevin regime. In this paper, we report the experimental realization of optical parametric down-conversion in the Langevin regime on a chip. By precisely controlling the loss inherently tied to fluctuation, we observe the asymmetric Hong-Ou-Mandel dip - a hallmark of quantum fluctuation in the fluctuation-driven PDC, and the fluctuation-induced compression of single photons by nearly one order of magnitude. These findings pave the way for the manipulation of quantum fluctuation, quantum states, and system-reservoir interaction.

Manfred Eibl, Sascha Gaertner, Christian Kurtsiefer +2 more