Progress towards scalable quantum information systems using few-qubit electron-nuclear spin registers
Mikhail Lukin
Harvard University, US.
Abstract: It is generally believed that complex environment represents the main obstacle for realization of ideas from quantum information science in solid-state systems. This talk demonstrates that the environment of single electron spins can be understood and controlled and, under certain condition, can be used as a very useful resource.
Specifically we describe a technique that makes use of coherent manipulation of a single electron spin and individual nuclear spins in its local environment to create a controllable quantum register composed of a few quantum bits (qubits). Using optical and microwave manipulation of an electron spin associated with the Nitrogen-Vacancy (NV) color center in diamond, we demonstrate robust initialization of a two-qubit register at room temperature and transfer of arbitrary quantum states between individual electron and nuclear spin qubits. We further observe coherent interactions between individual nuclear spins, and demonstrate that they have excellent coherence properties on time scales approaching seconds.
We next describe how such few-qubit registers can be used as a basis for optically coupled quantum information systems. In analogy to recent ideas involving trapped ions, this hybrid approach combines the probabilistic and determistic techniques from quantum optics, mesoscopic physics and NMR to yeild robust, potentially scalable multi-qubit system. As an outlook we describe our recent work on developing efficient optical interconnects between qubits based on combining ideas of cavity QED with nanowire surface plasmons.