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

Abstract

Chiral single photons are highly sought to enhance encoding capacities or enable propagation-dependent routing in nonreciprocal devices. Unfortunately, most semiconductor quantum emitters (QE) produce only linear polarized photons unless external magnets are applied. Magnetic proximity coupling utilizing 2D ferromagnets promises to make bulky external fields obsolete. Here we directly grow Fe-doped MoS2 (Fe:MoS2) via CVD that displays pronounced hard ferromagnetic properties even in monolayer form. This approach with monolayer ferromagnets enabled us to fully utilize the strain from the pillar stressor on the substrate to form QE in WSe2 deterministically. The Fe:MoS2/WSe2 heterostructures display strong hysteretic magneto-response and high-purity chiral single photons with a circular polarization degree of 92±1% without external magnetic fields. Furthermore, the chiral single photons are robust against uncontrolled external stray fields. This ability to manipulate quantum states and transform linear polarized photons into high-purity chiral photons on-chip enables nonreciprocal device integration in quantum photonics.

Solid‐State Single‐Photon Sources: Recent Advances for Novel Quantum Materials

“…Further interesting developments in terms of shaping the photonic environment of single photon emitters include magneto‐optical structures enabling single photon emission with well‐defined orbital angular momenta. [ 327–329 ] Heterostructures such as CrI 3 /WSe 2 and WSe 2 /NiPS 3 show chiral single photon emission due to built‐in magnetic fields, offering promising paths for single spin control. [ 330,331 ]…”

“…Further interesting developments in terms of shaping the photonic environment of single photon emitters include magneto-optical structures enabling single photon emission with well-defined orbital angular momenta. [327][328][329] Heterostructures such as CrI 3 /WSe 2 and WSe 2 /NiPS 3 show chiral single photon emission due to built-in magnetic fields, offering promising paths for single spin control. [330,331] On the quantum applications for these novel materials, we conclude that the lack of competent indistinguishability halts the experimentation on protocols that require photon interference (entanglement distribution); yet the moderate values of brightness in TMD QDs, and especially, in hBN defects, have triggered notable QKD tests.…”

Inducing Circularly Polarized Single-Photon Emission via Chiral-Induced Spin Selectivity

“…Significantly, while there are extensive examples of room-temperature chiral classical light-emitting devices, as well as some chiral single-photon sources operating at ultralow temperature, there remains a lack of chiral quantum-light sources operating at ambient conditions. ,,, Future optimization of the revealed mechanisms may present a viable means of realizing the on-demand generation of single photons with a known circular polarizationa key component for nonreciprocal quantum nanophotonic devices and chiral quantum sensing applications …”