Search

The long-range interaction between Rydberg-excited atoms endows a medium with large optical nonlinearity. Here, we demonstrate an optical switch to operate on a single photon from an entangled photon pair under a Rydberg electromagnetically induced transparency configuration. With the presence of the Rydberg blockade effect, we switch on a gate field to make the atomic medium nontransparent thereby absorbing the single photon emitted from another atomic ensemble via the spontaneous four-wave mixing process. In contrast to the case without a gate field, more than 50% of the photons sent to the switch are blocked, and finally achieve an effective single-photon switch. There are on average 1–2 gate photons per effective blockade sphere in one gate pulse. This switching effect on a single entangled photon depends on the principal quantum number and the photon number of the gate field. Our experimental progress is significant in the quantum information process especially in controlling the interaction between Rydberg atoms and entangled photon pairs. [ABSTRACT FROM AUTHOR]

Nowadays the most intriguing features of wave-particle complementarity of single-photons are exemplified by the famous Wheeler's delayed-choice experiment with linear optics, nuclear magnetic resonance, and integrated photonic device systems in the optical platform. Until now, the delayed-choice experiments are demonstrated by either massless photons or massive particles, such as atoms, however, there is no report demonstrating Wheeler's ideas in a hybrid system which consists of photons and atoms simultaneously. Here, we demonstrate a Wheeler's delayed-choice experiment in an interface of light and atomic memory, in which the cold atomic memory makes the heralded single-photon divided into a superposition of atomic collective excitation and leaked pulse, thus acting as memory-based beam-splitters. We observe the intermediate states between particle and wave behavior by changing the relative proportion of the quantum random number generator, the second memory efficiency, and the relative storage time of two memories. The reported results confirm Bohr's view that it makes no sense to illustrate the wave-like or particle-like behavior of light and matter before the measurement happens, and are helpful for improving our comprehension of the complementarity principle under the interface of light-atom interaction. [ABSTRACT FROM AUTHOR]

The complex interactions between orbital angular momentum (OAM) of light and atoms are particularly intriguing in the areas of quantum optics and quantum information. Building a versatile high-dimensional quantum network needs broad spiral-bandwidth for preparing higher-quanta OAM mode and resolving the bandwidth mismatch in spatial space. Here, we demonstrate a broad spiral-bandwidth quantum-interface between photon and memory. Through twisted fields of the writing and reading, the correlated OAM distribution between photon and memory is significantly broadened. This broad spiral-bandwidth quantum-interface could be spanned in multiplexing regime and could work in high-quanta scenario with capability of ∣ l ∣ = 30, and we demonstrate the entanglement within 2-D subspace with a fidelity of 80.5 ± 4.8% for high l . Such state-of-the-art technology to freely control the spatial distribution of OAM memory is very helpful to construct high-dimensional quantum networks and provides a benchmark in the field of actively developing methods to engineer OAM single photon from matters. The interaction between orbital angular momentum (OAM) of light and atoms can be used to store and retrieve high-dimensional information and hence has been proposed as an efficient way for quantum information networks. The authors present a scheme to store photons with a large OAM by implementing classical write and read pulses in higher OAM states. [ABSTRACT FROM AUTHOR]