Quantum entanglement, initialization and readout of nuclear spin qubits with an electric current




Stemeroff, Noah

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The ability to control the evolution of quantum systems would open the door to a new world of information processing. Nuclear spin qubits in the solid state offer the longest coherence times, of the order of a few seconds, however their initialization, readout and coupling are yet to be demonstrated. This thesis addresses the physical manipulation of nuclear spin qubits with a classical electric current. Our main result is the development of a mechanism that provides high contrast initialization and readout of nuclear spin qubits using their interaction with conduction electrons. However, we also show that conduction electrons can not be used to entangle nuclear spin qubits without destroying the nuclear spin qubit coherence. We show this by demonstrating that the quality factor of a Ruderman-Kittel-Kasuya-Yosida (RKKY) gate is always low for electron as well as nuclear spin qubits. In conclusion, we establish the viability of a quantum computer architecture based on nuclear spins that relies on conduction electrons for quantum read-out and initial- ization. For coherent entanglement, we argue that the usual direct exchange interac- tion is still the best option.



quantum, systems, qubit, nuclear