Putting a spin on photon entanglement

Lixiang Chen, Weilong She

Single photons emerging from Pancharatnam-Berry phase optical elements (q plates) exhibit entanglement in the degrees of freedom of spin and orbital angular momentum. We put forward an experimental scheme for probing the spin-orbit correlations of single photons. It is found that the Clauser-Horne-Shimony-Holt parameter S for the single-photon spin-orbit entangled state could be as high as 2√2, evidently violating the Bell-like inequality and thus invalidating the noncontextual hidden variable theories.

Xiaojing Liu, Xiang-Yao Wu, Jingbin Lu +9 more

Mladen Pavičić

We present an experiment which prepare entanglement between photons that nowhere interacted and whose paths nowhere crossed. The experiment puts together two photons from two (non-maximal) singlet-like photon pairs and make them interfere at an asymmetrical beam splitter. As a result one finds polarization correlations between the other companion photons from the pairs whose paths nowhere crossed each other even when no polarization measurements have been carried out on the former photons. The latter set of photons that nowhere interacted are therefore event-ready prepared by their pair-companion photons. The result reveals nonlocality as a property of selection which can even be a preselection. It also reveals that one can predict spin-correlated behaviour of photons in space and at beam splitters by controlling a no-spin observable. [From the Book of Abstracts as appeared at the Workshop.]

Chao‐Yang Lu, Jian-Wei Pan

Krishna Thyagarajan

Evyatar Sabag, Shlomi Bouscher, Raja Marjieh +1 more

Here we propose a new efficient method to preform full Bell-state analysis based on photon-pair detection in a semiconductor quantum-well (QW) based structure in proximity to a superconductor. We show that for certain photon energies one-photon absorption is forbidden, and only two-photon absorption into Cooper-pairs can occur (Fig. 1.a), with rates enhanced by orders of magnitude compared to other nonlinear processes. Putting the device in proximity to a superconductor allows light-matter interactions only with a specific entangled photon-pair [6], due to the spin-entangled states in BCS. We theoretically demonstrate Bell-state analysis on polarization entangled photons tagged by different energies.