The generalization of geometric phase from the pure states to the mixed states may have potential applications in constructing geometric quantum gates. We here investigate the mixed state geometric phases and visibili...The generalization of geometric phase from the pure states to the mixed states may have potential applications in constructing geometric quantum gates. We here investigate the mixed state geometric phases and visibilities of the trapped ion system in both non-degenerate and degenerate cases. In the proposed quantum system, the geometric phases are determined by the evolution time, the initial states of trapped ions, and the initial states of photons. Moreover, special periods are gained under which the geometric phases do not change with the initial states changing of photon parts in both non-degenerate and degenerate cases. The high detection efficiency in the ion trap system implies that the mixed state geometric phases proposed here can be easily tested.展开更多
Several schemes have been proposed to prepare two-mode squeezed state and entanglement state betweenmotional states of a single trapped ion and light.Preparation of two-mode squeezed state is based on interaction ofa ...Several schemes have been proposed to prepare two-mode squeezed state and entanglement state betweenmotional states of a single trapped ion and light.Preparation of two-mode squeezed state is based on interaction ofa trapped ion located in light cavity with cavity field.Preparation of entanglement state is based on interaction of atrapped ion located in light cavity with cavity field and a traveling wave light field.展开更多
We propose a scheme to implement two-qubit controlled quantum phase gate（CQPG） via a single trapped two-level ion located in the standing wave field of a quantum cavlty, in which the trap works beyond the Lamb--Dick...We propose a scheme to implement two-qubit controlled quantum phase gate（CQPG） via a single trapped two-level ion located in the standing wave field of a quantum cavlty, in which the trap works beyond the Lamb--Dicke limit. When the light field is resonant with the atomic transition ｜g） →← ｜e） of the ion located at the antinode of the standing wave, we can perform CQPG between the internal and external states of the trapped ion; while the frequency of the light field is chosen to be resonant with the first red sideband of the collective vibrational mode of the ion located at the node of the standing wave, we can perform CQPG between the cavity mode and the collective vibrational mode of the trapped ion. Neither the Lamb--Dicke approximation nor the assistant classical laser is needed. Also we can generate a GHZ state if assisted with a classical laser.展开更多
We describe a scheme for the generation of macroscopic quantum-interference states for a collection of trapped ions by a single geometric phase operation. In the scheme the vibrational mode is displaced along a circle...We describe a scheme for the generation of macroscopic quantum-interference states for a collection of trapped ions by a single geometric phase operation. In the scheme the vibrational mode is displaced along a circle with the radius proportional to the number of ions in a certain ground electronic state. For a given interaction time, the vibrational mode returns to the original state, and the ionic system acquires a geometric phase proportional to the area of the circle, evolving from a coherent state to a superposition of two coherent states. The ions undergo no electronic transitions during the operation. Taking advantage of the inherent fault-tolerant feature of the geometric operation, our scheme is robust against decoherence.展开更多
Based on squeezed operators this paper has implemented an ideal unconventional geometric quantum gate （GQG） in ion trap-optical cavity system by radiating the trapped ions with the cavity field of frequency ωc and ...Based on squeezed operators this paper has implemented an ideal unconventional geometric quantum gate （GQG） in ion trap-optical cavity system by radiating the trapped ions with the cavity field of frequency ωc and an external laser field of frequency ωL. It can ensure that the gate time is shorter than the coherence time for qubits and the decay time of the optical cavity by appropriately tuning the ionic transition frequency ω0, the frequencies of the cavity mode ωc and the vibrational mode v. It has also realized the unconventional GQG under the influence of the cavity decay based on the squeezed-like operators and found that the present scheme works well for the smaller cavity decay by investigating the corresponding fidelity and success probability.展开更多
We investigate the geometric phase and dynamic phase of a two-level fermionic system with dispersive interaction, driven by a quantized bosonic field which is simultaneously subjected to parametric amplification. It i...We investigate the geometric phase and dynamic phase of a two-level fermionic system with dispersive interaction, driven by a quantized bosonic field which is simultaneously subjected to parametric amplification. It is found that the geometric phase is induced by a counterpart of the Stark shift. This effect is due to distinct shifts in the field frequency induced by interaction between different states （｜e〉 and ｜g〉 ） and cavity field, and a simple geometric interpretation of this phenomenon is given, which is helpful to understand the natural origin of the geometric phase.展开更多
We have investigated the intensity squeezing of superposition of two photon-added coherent states and proposed a new method for preparation of photon-added coherent states and their superposition states.This method is...We have investigated the intensity squeezing of superposition of two photon-added coherent states and proposed a new method for preparation of photon-added coherent states and their superposition states.This method is based on interaction of the trapped ion with the traveling wave light fields with different frequencies.展开更多
基金The project supported by the Natural Science Foundation of Education Bureau of Jiangsu Province of China under Grant No. 05KJB140008. The author is grateful to Prof. Z.D. Wang, Dr. S.L. Zhu, and Prof. Z.C. Dong for critical reading of the manuscript and useful suggestions.
文摘The generalization of geometric phase from the pure states to the mixed states may have potential applications in constructing geometric quantum gates. We here investigate the mixed state geometric phases and visibilities of the trapped ion system in both non-degenerate and degenerate cases. In the proposed quantum system, the geometric phases are determined by the evolution time, the initial states of trapped ions, and the initial states of photons. Moreover, special periods are gained under which the geometric phases do not change with the initial states changing of photon parts in both non-degenerate and degenerate cases. The high detection efficiency in the ion trap system implies that the mixed state geometric phases proposed here can be easily tested.
基金Supported by the Natural Science Foundation of Anhui Province of China under Grant No.090412060 Natural Science Foundation of the Education Committee of Anhui Province of China under Grant No.KJ2008A029
文摘Several schemes have been proposed to prepare two-mode squeezed state and entanglement state betweenmotional states of a single trapped ion and light.Preparation of two-mode squeezed state is based on interaction ofa trapped ion located in light cavity with cavity field.Preparation of entanglement state is based on interaction of atrapped ion located in light cavity with cavity field and a traveling wave light field.
基金Project supported by the National Natural Science Foundation of China （Grant No 10374025）.
文摘We propose a scheme to implement two-qubit controlled quantum phase gate（CQPG） via a single trapped two-level ion located in the standing wave field of a quantum cavlty, in which the trap works beyond the Lamb--Dicke limit. When the light field is resonant with the atomic transition ｜g） →← ｜e） of the ion located at the antinode of the standing wave, we can perform CQPG between the internal and external states of the trapped ion; while the frequency of the light field is chosen to be resonant with the first red sideband of the collective vibrational mode of the ion located at the node of the standing wave, we can perform CQPG between the cavity mode and the collective vibrational mode of the trapped ion. Neither the Lamb--Dicke approximation nor the assistant classical laser is needed. Also we can generate a GHZ state if assisted with a classical laser.
基金Supported by Funds from the State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University
文摘We describe a scheme for the generation of macroscopic quantum-interference states for a collection of trapped ions by a single geometric phase operation. In the scheme the vibrational mode is displaced along a circle with the radius proportional to the number of ions in a certain ground electronic state. For a given interaction time, the vibrational mode returns to the original state, and the ionic system acquires a geometric phase proportional to the area of the circle, evolving from a coherent state to a superposition of two coherent states. The ions undergo no electronic transitions during the operation. Taking advantage of the inherent fault-tolerant feature of the geometric operation, our scheme is robust against decoherence.
基金Project supported by the National Natural Science Foundation of China (Grant No 60667001)the Science Foundation of Yanbian University in China (Grant No 2007-31)
文摘Based on squeezed operators this paper has implemented an ideal unconventional geometric quantum gate （GQG） in ion trap-optical cavity system by radiating the trapped ions with the cavity field of frequency ωc and an external laser field of frequency ωL. It can ensure that the gate time is shorter than the coherence time for qubits and the decay time of the optical cavity by appropriately tuning the ionic transition frequency ω0, the frequencies of the cavity mode ωc and the vibrational mode v. It has also realized the unconventional GQG under the influence of the cavity decay based on the squeezed-like operators and found that the present scheme works well for the smaller cavity decay by investigating the corresponding fidelity and success probability.
基金Supported by the National Natural Science Foundation of China under Grant No 10575040.
文摘We investigate the geometric phase and dynamic phase of a two-level fermionic system with dispersive interaction, driven by a quantized bosonic field which is simultaneously subjected to parametric amplification. It is found that the geometric phase is induced by a counterpart of the Stark shift. This effect is due to distinct shifts in the field frequency induced by interaction between different states （｜e〉 and ｜g〉 ） and cavity field, and a simple geometric interpretation of this phenomenon is given, which is helpful to understand the natural origin of the geometric phase.
基金Supported by the Natural Science Foundation of Anhui Province under Grant No. 090412060
文摘We have investigated the intensity squeezing of superposition of two photon-added coherent states and proposed a new method for preparation of photon-added coherent states and their superposition states.This method is based on interaction of the trapped ion with the traveling wave light fields with different frequencies.
