Chiral Photonic Circuits for Deterministic Spin Transfer

Abstract

Chiral quantum optics has attracted considerable interest in the field of quantum information science. Exploiting the spin-polarization properties of quantum emitters and engineering rational photonic nanostructures has made it possible to transform information from spin to path encoding. Here, compact chiral photonic circuits with deterministic circularly polarized chiral routing and beamsplitting are demonstrated using two laterally adjacent waveguides coupled with quantum dots. Chiral routing arises from the electromagnetic field chirality in waveguide, and beamsplitting is obtained via the evanescent field coupling. The spin-and position-dependent directional spontaneous emission are achieved by spatially selective micro-photoluminescence measurements, with a chiral contrast of up to 0.84 in the chiral photonic circuits. This makes a significant advancement for broadening the application scenarios of chiral quantum optics and developing scalable quantum photonic networks.

Revealing broken valley symmetry of quantum emitters in WSe2 with chiral nanocavities

“…1 a, the uncoupled transitions of QE are not perfectly circularly polarized for the two different channels between the defect states and two valence bands, which is also confirmed by the measured D C P as shown in Fig. 4 a, e. Even after overcoming the electron-hole exchange interaction at a higher magnetic field, the saturated D C P around 50% is still much lower that in In(Ga)As/(Al)GaAs quantum dots with a complete circular polarization 44 , 48 , 54 . Previous experiments 24 , 47 and density functional theory (DFT) calculations 29 also show similar results that a partial circular polarization with cross-circularly polarized components mixed in the emission spectra of WSe 2 QEs.…”

Chiral single photons from deterministic quantum emitter arrays via proximity coupling to van der Waals ferromagnets

“…Combining the chirality of light with single-photon emission has created a new forefront of research in quantum optics [1]. Optical chirality, classified by right-(σ + ) and left-(σ − ) circular polarization, provides advances in encoding capacities in quantum information [2][3][4] and quantum computing [5][6][7]. The chirality also enables propagation-dependent routing, i.e., nonreciprocity through time-reversal symmetry breaking [8].…”