Integrated optical quantum circuits are increasingly gaining attention as a possible solution for scalable quantum technologies with important applications to quantum simulations. Quantum communication provides secure information transmission, but the distance over which quantum states of light can be distributed without significant disturbance is limited due to inescapable losses and noise in optical elements. Loss is the greatest challenge facing the implementation of integrated photonic technologies, and it is inescapable in experimental reality.

In recent years there has been growing interest in structures with spatially inhomogeneous losses. Light propagation in waveguiding structures with spatially distributed sections of loss can be used for implementation of quantum plasmonic circuits, which are able to strongly confine light to sub-wavelength dimensions, as well as for parity-time (PT) symmetric structures, with phase transition associated with PT-symmetry breaking that opens new possibilities for light manipulation.

In this seminar I will give a brief overview of my PhD research focused on the controllable classical and quantum dynamics of optical frequency conversion and photon-pair generation processes in quadratic nonlinear photonic integrated circuits in the presence of losses. I will discuss spontaneous parametric down-conversion (SPDC), sum-frequency generation (SFG) and optical parametric amplification (OPA) processes in nonlinear structures governed by non-Hermitian Hamiltonians, including but not limited to PT-symmetric systems.