Deterministic single photon subtraction with a cascade of waveguide-coupled atoms.

We present a specialized photon subtraction scheme that allows for the deterministic extraction of single photons from multiphoton states while preserving the input single-photon states unaltered. The proposed device integrates two Λ-type emitters with transitions selectively coupled to a single chiral waveguide through single photon Raman interaction (SPRINT). We develop a comprehensive theoretical model for the system using the input-output formalism within the SLH framework and conduct numerical simulations to analyze its interaction with traveling few-photon pulses of coherent light.

Detecting Single Microwave Photons with NV Centers in Diamond.

We propose a scheme for detecting single microwave photons using dipole-induced transparency (DIT) in an optical cavity resonantly coupled to a spin-selective transition of a negatively charged nitrogen-vacancy (NV) defect in diamond crystal lattices. In this scheme, the microwave photons control the interaction of the optical cavity with the NV center by addressing the spin state of the defect. The spin, in turn, is measured with high fidelity by counting the number of reflected photons when the cavity is probed by resonant laser light.