Single-shot quantum nondemolition measurement of a quantum-dot electron spin using cavity exciton-polaritons

摘要: We propose a scheme to perform single-shot quantum non-demolition (QND) readout of the spin an electron trapped in semiconductor dot (QD). Our proposal relies on interaction QD with optically excited, well (QW) microcavity exciton-polaritons. The spin-dependent Coulomb exchange between and cavity polaritons causes phase intensity response left circularly polarized light be different that right light, such way electron's can inferred from linearly probe. show that, by careful design sample coupled QW, it is possible eliminate spin-flip Raman transitions. Thus, QND measurement performed within few 10's nanoseconds fidelity $\sim 99.9$%. This improves upon current optical techniques across multiple metrics, including speed scalability.