All-optical switch and transistor gated by one photon

Wenlan Chen, Kristin M. Beck, Robert Bücker +4 more

The realization of an all-optical transistor, in which one "gate" photon controls a "source" light beam, is a long-standing goal in optics. By stopping a light pulse in an atomic ensemble contained inside an optical resonator, we realized a device in which one stored gate photon controls the resonator transmission of subsequently applied source photons. A weak gate pulse induces bimodal transmission distribution, corresponding to zero and one gate photons. One stored gate photon produces fivefold source attenuation and can be retrieved from the atomic ensemble after switching more than one source photon. Without retrieval, one stored gate photon can switch several hundred source photons. With improved storage and retrieval efficiency, our work may enable various new applications, including photonic quantum gates and deterministic multiphoton entanglement.

Hannes Gorniaczyk, Christoph Tresp, J. Schmidt +2 more

We report on the realization of an all-optical transistor by mapping gate and source photons into strongly interacting Rydberg excitations with different principal quantum numbers in an ultracold atomic ensemble. We obtain a record switch contrast of 40% for a coherent gate input with mean photon number one and demonstrate attenuation of source transmission by over ten photons with a single gate photon. We use our optical transistor to demonstrate the nondestructive detection of a single Rydberg atom with a fidelity of 0.72(4).

David F. P. Pile

Charles S. Adams

An all-optical transistor is a device in which a gate light pulse switches the transmission of a target light pulse with a gain above unity.The gain quantifies the change of the transmitted target photon number per incoming gate photon.We study the quantum limit of one incoming gate photon and observe a gain of 20.The gate pulse is stored as a Rydberg excitation in an ultracold gas.The transmission of the subsequent target pulse is suppressed by Rydberg blockade, which is enhanced by a Förster resonance.The detected target photons reveal in a single shot with a fidelity above 0.86 whether a Rydberg excitation was created during the gate pulse.The gain offers the possibility to distribute the transistor output to the inputs of many transistors, thus making complex computational tasks possible.