Control Over Frequency- and Angular Spectrum of Biphoton Field and its Possible Application for Quantum Communications
KTH Applied Physics seminars
Tuesday 07 June 2011
to 11:00 at
Prof Sergey Kulik (M.V. Lomonosov Moscow State University, Russia)
Basically we are focussing on multimode entanglement of bipartite systems. Several operational quantifiers that can be measured in experiment (Fedorov’s ratio, Schmidt number and subsystem purity) will be discussed. Based on Spontaneous Parametric Down-Conversion we consider generic multidimensional optical bipartite system with controllable dimension and entanglement degree. A concept of Schmidt decomposition plays a central role; some ways how to perform the measurements in Schmidt basis will be discussed. In particular we analyze experimental challenges with measurement of correlation properties of biphoton states characterised by angular and frequency degrees of freedom.
Adequate methods for selecting given spatial Schmidt modes of parametric down-conversion (PDC) have been developed for shaping its angular/frequency spectrum. For instance it can be realized with Spatial Light Modulators. The second technique relates to affecting upon optical properties of the emitting crystal via thermo- and electro-optical effects and leads to inhomogeneous broadening of the spectrum and its frequency/angular shaping.