Narrow-band Multi-photon Generation for Quantum Information Applications

The harness of quantum mechanical phenomena allows for new quantum technology that holds the promise to advance a variety of information processing tasks. In particular, single photons are a promising quantum system due to their robustness and mobility. This project aims to develop a new single-photon source that emits multiple photons whose frequency is very well defined – the photons have an extreme narrow-bandwidth. This opens the path for using the frequency-spectrum and the associated coherence length of photons, i.e. the length of which photons can interfere, as additional and novel feature for complex quantum information tasks.

Within this project we will generate multiphoton states in a controlled manner, where each photon’s coherence length is in the order of meters for performing quantum computations that rely on complex interferometric networks. In addition we will perform so-called loophole-free quantum computations that are based on the superposition of the order of quantum gates. These experiments will not only provide new insights in complex quantum computations but also break the ground for boosting the applicability of optical quantum computing when using narrow-bandwidth photons.

The narrow linewidth of the generated multiphoton states is also suitable for resonant coupling to atomic transitions, which is important for tailored light matter interactions. We will build our source in a compact and portable arrangement for investigating two-photon quantum computer gates that use atoms as medium. This will be done in collaboration with the research group of Arno Rauschenbeutel at the Technische Universität.