Quantum Information Processing Based On Spin System In Carbon Material

Quantum information is a new interdiscipline based on quantum mechanics and information science.Quantum information exploits fundamental features of(hybrid)quantum systems to realize the measurement,processing and storage of information.Over the past decade,a lot of research has been done with many exciting achievements in the field of quantum information science and technology.Among all the physical systems that can realize quantum information processing,nitrogen-vacancy centers in diamond with excellent coherent properties and carbon-nanotube double quantum dots with scalability become two of the promising candidates for the implementation of quantum devices.In this thesis,we propose new schemes for quantum sensing and quantum computing based on nitrogen-vacancy centers in diamond and carbon-nanotube double quantum dot.The main results of this thesis are summarized as follows:1.We propose a magnetic scanning microscopy scheme using a hybrid quantum system that consists of nitrogen-vacancy center in diamond and radical pair molecule.In this scheme the radical pair spins interact with the target spin,resulting in the change in the spin dynamics of the radical pair,which is detected by the highly sensitive nitrogen-vacancy center spin sensor.The radical pair molecule with a sub-nanometer dimension plays the role of signal amplification,and facilitates the achievable high spatial resolution.With detailed numerical simulation,we demonstrate that our scheme is able to detect single spin and to implement magnetic scanning imaging with high spatial resolution under ambient conditions.2.We propose a scheme for quantum sensing based on a carbon nanotube double quantum dot by applying continuous electrical driving.We show that the scheme can be used to measure the spectrum of a weak oscillating magnetic field,and to implement nanoscale magnetic resonance spectroscopy on the single-molecule level.The high sensitivity of the scheme is due to the unique features of a large valley g-factor of the carbon nanotube double quantum dot and ultra-small dimension of the single-wall carbon nanotube.The scheme provides a new way towards the realization of integrated on-chip quantum sensing devices.3.We present a hybrid quantum system consisting of nitrogen-vacancy center in diamond and carbon-nanotube double quantum dots.Based on such a hybrid quantum system,we propose a scheme to achieve steady-state entanglement between nitrogen-vacancy center spins in diamond with spatial separations over micrometers.The steady-state entanglement between the electron spins of distant nitrogen-vacancy centers can be used to realize an entangling gate between the nuclear spins associated with the nitrogen-vacancy centers via the hyperfine coupling.Furthermore,we propose a scheme to prepare two-dimentional cluster states in a scalable manner,which represent a universal resource for one-way quantum computing.The scheme offers a new approach towards scalable solid-state spin based quantum computing.