Regensburg 2016 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 23: Quantum Information Systems
(Joint session of HL, MA, O and TT organized by HL)

TT 23.1: Talk

Tuesday, March 8, 2016, 09:30–09:45, H15

Nuclear spins as quantum memories for quantum networks and repeaters — •Andreas Reiserer^{1, 2}, Norbert Kalb^{1, 2}, Machiel Blok^{1, 2}, Koen van Bemmelen^{1, 2}, Tim Taminiau^{1, 2}, and Ronald Hanson^{1, 2} — ¹Kavli Institute of Nanoscience, TU Delft, The Netherlands — ²QuTech, TU Delft, The Netherlands

A future quantum network will consist of quantum processors that are connected by quantum channels, just like conventional computers are wired up to form the Internet. To realize such network, we plan to use spin qubits in diamond, which combine access to few-qubit nuclear-spin registers with exceptional coherence properties. However, preserving the coherence of the register while generating entanglement between remote spins is an open challenge.

Here, we investigate the coherence of single ¹³C spins that occur in an otherwise spin-free diamond sample of natural isotope abundance. Five individual nuclear spins are controlled via the weak hyperfine interaction with the electronic spin of a nitrogen vacancy (NV) center in a strong magnetic field. We encode quantum bits in the nuclear spins and investigate the loss of coherence caused by repeated electron spin initialization, which is required for any quantum protocol that is subject to errors. Encoding the qubits in a decoherence-protected subspace of two rather than one nuclear spin increases the robustness of the protocol and enables the investigation of a large parameter space with a single sample. Our results open perspectives for the realization of large scale quantum networks and quantum repeaters using NV centers with weakly coupled nuclear spins.