Room-temperature high-speed nuclear-spin quantum memory in diamond

This is the authors' abstract. We don't add key points for this paper.

Quantum memories provide intermediate storage of quantum information until it is needed for the next step of a quantum algorithm or a quantum communication process. Relevant figures of merit are therefore the fidelity with which the information can be written and retrieved, the storage time, and also the speed of the read-write process. Here, we present experimental data on a quantum memory consisting of a single ¹³C nuclear spin that is strongly coupled to the electron spin of a nitrogen-vacancy (NV) center in diamond. The strong hyperfine interaction of the nearest-neighbor carbon results in transfer times of 300 ns between the register qubit and the memory qubit, with an overall fidelity of 88$%$ for the write-storage-read cycle. The observed storage times of 3.3 ms appear to be limited by the T₁ relaxation of the electron spin. We discuss a possible scheme that may extend the storage time beyond this limit.