Speaker
Description
Quantum networks are an important part of the future infrastructure that will allow transmission of quantum information between quantum computers. There are many promising hardware platforms for realising quantum networks including light-matter interactions in atomic systems (Kimble, Nature, 453, 2008) or solid-state systems (Chou et al, Nature, 561, 2018). Trivalent rare-earths embedded in crystals, for example, have demonstrated state-of-the-art performance due to their narrow optical linewidths and long coherence times. However, one drawback of these materials is their weak interactions with light (small transition dipole moment $\mu$) which can reduce the fidelity of the entanglement that links two quantum systems together.
Engineering the crystal to modify the electrostatic potential (crystal field) the rare-earth experiences is a potential avenue to enhance its interaction with light. But how much of an enhancement could be obtained with this novel approach? This paper will cover the numerical results obtained from attempting to increase the magnetic transition dipole moment ($\mu_\text{MD}$) in trivalent erbium (Er$^{3+}$) by engineering the crystal field of the host crystal. A computational optimisation of $\mu_\text{MD}$ for the $Z_1 \to Y_1$ transition of erbium was performed with respect to the crystal field parameters ($B^k_q$), which define the field's strength and symmetry in the crystal field Hamiltonian $\hat{H}_\text{CF} = \sum_{k,q} B^k_q \hat{C}^{(k)}_q$. As such, the results are independent of the crystal material.
The optimisation reveals minimal increases in $\mu_\text{MD}$ are possible when erbium is placed in a crystal. However, crystals with high axial symmetry will exhibit the highest $\mu_\text{MD}$ when compared against different crystal structures, opening up avenues for increasing $\mu_\text{MD}$ in existing materials. This approach is also discussed for the rare-earths Praseodymium, Europium, and Ytterbium due to their significance for developing quantum technologies, and optimisation of the electric transition dipole moment with potential increases due to its dependence on the local electronic environment.
| I am the presenting author | Yes |
|---|