We utilize the general displacement operator proposed recently [C.Y. Chen, et al., Phys. Rev. A 74 （2006） 032328] to investigate a high-speed geometric quantum computation via vibrational mode decay of two trapped t...We utilize the general displacement operator proposed recently [C.Y. Chen, et al., Phys. Rev. A 74 （2006） 032328] to investigate a high-speed geometric quantum computation via vibrational mode decay of two trapped thermal ions. We find that, under some special conditions, the geometric phase gating is somewhat faster in the heating case than in the ideal case. We also investigate analytically the influence from the vibrational mode heating on the fidelity and the success probability of the implementation.展开更多
A scheme is presented for generating W states for three o()four trapped ions in thermal motion. The scheme works in the regime, where the Rabi frequency of the laser field is on the order of the trap frequency, result...A scheme is presented for generating W states for three o()four trapped ions in thermal motion. The scheme works in the regime, where the Rabi frequency of the laser field is on the order of the trap frequency, resulting a fast entanglement speed, which is of importance in view of decoherence.展开更多
Electromagnetic ion cyclotron (EMIC) waves,particularly their generation and excitation mechanisms,have been a subject of wide interest because of their potential importance in ion acceleration and heating.In this wor...Electromagnetic ion cyclotron (EMIC) waves,particularly their generation and excitation mechanisms,have been a subject of wide interest because of their potential importance in ion acceleration and heating.In this work,the parameter-dependence of EMIC instabilities is investigated with a combined loss-cone and temperature anisotropy distribution for suprathermal ions.The calculation of the linear growth rate of EMIC waves with an arbitrary propagation angle is presented.The results show that the growth rates of EMIC waves propagating quasi-perpendicular to the ambient magnetic field increase as the loss-cone parameter α increases,whereas the growth rates of EMIC waves propagating quasi-parallel to the ambient magnetic field increase as the temperature anisotropy parameter AT increases.This indicates that the free energies associated with the loss-cone and temperature anisotropic distributions are primarily responsible for the excitation of the quasi-perpendicular and parallel propagating EMIC waves,respectively,and provides us with a more comprehensive understanding of excitation and generation mechanisms for EMIC waves in space plasmas.展开更多
An alternative scheme is proposed for one-step generation of multiparticle cluster state with trapped ionsin thermal motion.In this scheme,the ions are simultaneously illuminated by a standing-wave laser tuned to the ...An alternative scheme is proposed for one-step generation of multiparticle cluster state with trapped ionsin thermal motion.In this scheme,the ions are simultaneously illuminated by a standing-wave laser tuned to the carrier.During the operations,the vibrational mode is virtually excited,thus the quantum operations are insensitive to theheating.It is shown that the high fidelity multiparticle entanglement could be generated in just one step even includingthe small fluctuations of parameters.In addition,the ion does not need to be exactly positioned at the node of thestanding wave,which is also important from the viewpoint of experiment.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No. 10774042the Natural Science Fondation of Hunan Province under Grant No. 09JJ3121the National Fundamental Research Program of China under Grant Nos. 2005CB724500 and60490280
文摘We utilize the general displacement operator proposed recently [C.Y. Chen, et al., Phys. Rev. A 74 （2006） 032328] to investigate a high-speed geometric quantum computation via vibrational mode decay of two trapped thermal ions. We find that, under some special conditions, the geometric phase gating is somewhat faster in the heating case than in the ideal case. We also investigate analytically the influence from the vibrational mode heating on the fidelity and the success probability of the implementation.
文摘A scheme is presented for generating W states for three o()four trapped ions in thermal motion. The scheme works in the regime, where the Rabi frequency of the laser field is on the order of the trap frequency, resulting a fast entanglement speed, which is of importance in view of decoherence.
基金supported by the National Natural Science Foundation of China (10973043,41074107)National Basic Research Program of China (2011CB811402)
文摘Electromagnetic ion cyclotron (EMIC) waves,particularly their generation and excitation mechanisms,have been a subject of wide interest because of their potential importance in ion acceleration and heating.In this work,the parameter-dependence of EMIC instabilities is investigated with a combined loss-cone and temperature anisotropy distribution for suprathermal ions.The calculation of the linear growth rate of EMIC waves with an arbitrary propagation angle is presented.The results show that the growth rates of EMIC waves propagating quasi-perpendicular to the ambient magnetic field increase as the loss-cone parameter α increases,whereas the growth rates of EMIC waves propagating quasi-parallel to the ambient magnetic field increase as the temperature anisotropy parameter AT increases.This indicates that the free energies associated with the loss-cone and temperature anisotropic distributions are primarily responsible for the excitation of the quasi-perpendicular and parallel propagating EMIC waves,respectively,and provides us with a more comprehensive understanding of excitation and generation mechanisms for EMIC waves in space plasmas.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10704017, 11074036National Fundamental Research Program of China under Grant No. 2007CB936300
文摘An alternative scheme is proposed for one-step generation of multiparticle cluster state with trapped ionsin thermal motion.In this scheme,the ions are simultaneously illuminated by a standing-wave laser tuned to the carrier.During the operations,the vibrational mode is virtually excited,thus the quantum operations are insensitive to theheating.It is shown that the high fidelity multiparticle entanglement could be generated in just one step even includingthe small fluctuations of parameters.In addition,the ion does not need to be exactly positioned at the node of thestanding wave,which is also important from the viewpoint of experiment.
