Applied Physics Seminar

Abstract: Nanoscale systems offer new functionalities in quantum technologies, like single qubit control and detection, or extremely localized sensing. The ability to couple qubits with light is an attractive feature for these systems to enableinterfacing with photonic qubits, creating light matter entanglement or fast processing of quantum information. Rare earth ions are promising candidates for
this purpose1-3, as they can show record long optical and spin coherence lifetimes in bulk crystals4. However, maintaining these properties at the nanoscale can be challenging, as surface effects for example can cause strong dephasing.

In this talk, we will discuss recent results obtained in our group on europium doped nanoparticles. These materials show optical and spin coherence lifetimes of 7 μs 5 and 1.3 ms at low temperature6. Moreover, spin dephasing can be controlled by trains of optical pulses, resulting in coherence lifetimes up to 8 ms 6. This is the highest reported value for optically addressable spins in any nano-material. These particles could be placed in high-finesse fiber-based cavities to achieve efficient optical control and readout of nuclear spin qubits7. Combined with rare earths unique coherent properties, this
scheme opens the way to quantum memories with single ion processing capabilities, single photon sources or highly scalable quantum processors.