Speaker
Description
A system that can combine the complementary strengths of trapped ions and photons as carriers of quantum information is an appealing prospect. Ions provide long coherence times, high levels of quantum control and high-fidelity state readout, while photons are a natural choice for transmitting information over anything but very short distances. To interface these two platforms we use calcium ions, trapped close to the mode centre of a high-finesse optical cavity. The resulting ion-photon coupling allows us to produce single photons via a Raman transition. To study the properties of single photons produced via this method we use a linear Paul trap with macroscopic mirrors installed in its endcaps. With this weakly-coupled system we are able to compare the indistinguishability of the photons that are produced by two different schemes [1]. Alongside this work, we utilise a specialised endcap trap with an integrated fibre Fabry–Pérot cavity [2]. After optimisation of the position and localisation of the ion inside this cavity we have obtained a cavity coupling rate of 16.7 MHz, which is greater than both the rate of photon loss from the cavity, and the decay rate of the relevant excited state of the ion [3]. As a next step we have designed and are in the process constructing a next-generation, flexible, multi-zone trap system with strongly coupled ion-photon interface. This will act as a node of a distributed quantum computer, and allow for increased rates of remote ion-ion entanglement than can be achieved in free space systems.
References
[1] T. Walker et al., Phys. Rev. A 102, 032616 (2020)
[2] H. Takahashi et al., Phys. Rev. Lett. 124, 013602 (2020)
[3] C. Christoforou et al., Scientific Reports volume 10, 15693 (2020)
