Polariton polarization-sensitive phenomena in planar semiconductor microcavities

Abstract

From a theoretical point of view, we discuss a variety of phenomena linked to the spin and polarization degree of freedom of exciton-polaritons in semiconductor microcavities. We start with linear optical effects including the optical spin Hall effect, formation of polarization vortices and ballistic propagation of polarized exciton-polaritons. Next, the interplay between spin-dependent dynamics and Bose condensation in the 2D system of microcavity polaritons is addressed. Theoretically, this many-body system of interacting particles is described by the spinor Gross-Pitaevskii equations. These equations provide a description of the time evolution of polarized polariton fields under different conditions of optical excitation as well as an understanding of the phenomena of superfluidity, multistability and hysteresis via renormalization of the dispersion of elementary excitations. The comprehension of polarization-sensitive dynamics can be made through the introduction of several effective fields of different nature acting on the polariton pseudospin. The theory of parametric scattering of exciton-polaritons is presented, using the second quantization formalism. It is found that the combination of nonlinearity and various mechanisms of spin reorientation leads to self-organization and the formation of polarized patterns such as polarization crosses, vortices and rings. The manipulation of polariton spins can lead to various applications in signal processing, including the construction of optical logic gates and spin memory elements; the creation of spin currents; and the control of polarized signal propagation in the microcavity plane. The concept of polariton neurons is discussed in this connection.

Nonclassical statistics from a polaritonic Josephson junction

“…The first experimental proof of NBEC [4] has been rapidly followed by the demonstration of superfluidity [9] and of a variety of related effects such as phase coherence [10] and the formation of topological defects [11,12]. The two spin projections of polaritons allow the generation of controllable spin currents [13,14] and the formation of a spinor condensate hosting exotic excitations [15,16] in the presence of spin-orbit interaction or artificial gauge fields [17,18].…”

Robustness and observability of rotating vortex lattices in an exciton-polariton condensate

“…The polarization degree of freedom of the polaritons provides additional possibilities in pattern and defect formation, 32 such as allowing for spatially separate vortices of left and right polarization. 7 Further possibilities for pattern formation arise in the presence of a magnetic field that favors circular polarization and therefore competes with the interactions, which favor equal densities of the polarization components, and also with any anisotropy resulting from strain fields induced by mechanical stress.…”

An exciton-polariton mediated all-optical router

“…Furthermore, a characteristic pseudospin structure of polaritons [17] together with the possibility of their lateral confinement [18] has opened a promising field of research called "spin-optronics", based on the spin transport of bosonic particles. Obviously, in such investigations the chip architecture based on quasi onedimensional artificial microwires conquers the attention of researchers [19][20][21].…”