We propose a scheme for realization a quantum Controlled-NOT gate operation using two four-level atoms through a selective atom cavity interaction in cavity quantum electrodynamics system. In our protocol, the quantum...We propose a scheme for realization a quantum Controlled-NOT gate operation using two four-level atoms through a selective atom cavity interaction in cavity quantum electrodynamics system. In our protocol, the quantum information is encoded on the stable ground states of the two atoms. During the interaction between atoms and single-mode vacuum cavity-field, the atomic spontaneous emission is negligible as the large atom-cavity detuning effectively suppresses the spontaneous decay of the atoms. The influences of the dissipation and the deviation of interaction time on fidelity and corresponding success probability of the quantum Controlled-NOT gate and the experimental feasibility of our proposal are also discussed.展开更多
A very simpJe theoretical scheme is proposed to implement two-and three-qubit controlled-phase gates firstly only using a single resonant interaction between ladder-type three-level atoms and the single-mode cavity. I...A very simpJe theoretical scheme is proposed to implement two-and three-qubit controlled-phase gates firstly only using a single resonant interaction between ladder-type three-level atoms and the single-mode cavity. In the presented protocol, the quantum information is encoded on the stable ground states of the atoms （as the controlling qubits） and the zero- and one-photon Fock states of cavity-field （as the target qubit）. Under the influence of the atomic spontaneous emission, the decay of the cavity-mode, and deviation of the coupling strength, the three-qubit controlled- phase gate may have a comparatively high fidelity. The experimental feasibility of controlled-phase gate and the ease that is extended to realize N-qubit controlled-phase gate are also discussed.展开更多
In recent years, we have entered a period of increasing impact of world affairs on national politics and international security. Notwithstanding, the present debate on national security and nuclear proliferation, Angl...In recent years, we have entered a period of increasing impact of world affairs on national politics and international security. Notwithstanding, the present debate on national security and nuclear proliferation, Anglo-American ＂special relations＂ continue to be a subject of vigorous discussion influenced by the impact of new international emergencies as unstable countries acquire nuclear power and refuse ＂to reign＂ in their nuclear programmes （The Globe and Mail, 12 January 2012）. Along these lines the 71st anniversary of the Anglo-American Manhattan Project presents a unique opportunity to reappraise the Anglo-American wartime collaboration （or lack of） in atomic energy developments that resulted in the tragedy of nuclear weapons escalation. The Quebec Agreements of 1943-1944 were crafted to address the controlled flow of scientific information. But did this mean a trend toward more effective collaboration or toward greater American control of the atomic project？ This study explores the subject of nuclear politics from an unique vantage point of Anglo-Canadian and American-Canadian atomic diplomacy. In doing so, it will show that both the American and British atomic policy makers violated the Quebec Agreements. It seeks to demonstrate that （1） in the tangle of competition replacing cooperation, Canada was more important to the American atomic monopolists than the Anglo-AmcTican partnership, （2） the US-Canada Trade and Defence Agreements contributed to United States retaining exclusive control of the ＂absolute weapon＂, and that （3） their post-war nuclear energy agenda delayed Britain＇s atomic venture and isolated Britain from full participation in Arctic research. In practical terms, the emerging atomic policy in Washington boiled down to maintaining the American edge, come what may, and reducing British prestige in the post-war world. The article concludes by raising the question： did the United States, Britain, and Canada really work for atomic control？展开更多
Parameters of the power source used to control PV-10 piezoelectric crystal valve are following DC output voltage： 0 - 120 V, continuously controllable, linear enlargement factor of input direct current voltage： appr...Parameters of the power source used to control PV-10 piezoelectric crystal valve are following DC output voltage： 0 - 120 V, continuously controllable, linear enlargement factor of input direct current voltage： approximate 25 times, the accuracy of DC output voltage： ±5%, manual control and automatic control.展开更多
This study reports the synthesis of size-controlled Fe-MFI （Fe-substituted zeolites with the MFI topology） and their catalytic performances for DTO （dimethyl ether-to-olefins） reaction. The amount of HC1 and aging...This study reports the synthesis of size-controlled Fe-MFI （Fe-substituted zeolites with the MFI topology） and their catalytic performances for DTO （dimethyl ether-to-olefins） reaction. The amount of HC1 and aging temperature were decisive factors to control the particle size of Fe-MFI in the range of 50 nm to 600 nm. The introduction of Fe3＋ ions into the zeolitic framework was confirmed by UV （ultraviolet）-visible spectroscopy. In addition, it was observed that the strength of acid site in prepared Fe-MFI was weaker than that of commercial ZSM-5. With decrease in the particle size, the amount of deposited coke decreased so that the catalyst life for the DTO reaction was well promoted. The present catalysts showed the higher light-olefin selectivity （C2= ＋ C3= ＋ C4=） than commercial ZSM-5 catalysts mainly due to the suppression of the formation of paraffins; however, the Fe-MFI catalysts were deactivated rapidly because of their low activity for the cracking of alkenes.展开更多
We review some recent progresses on the study of ultracold Fermi gases with synthetic spin-orbit coupling.In particular,we focus on the pairing superfluidity in these systems at zero temperature.Recent studies have sh...We review some recent progresses on the study of ultracold Fermi gases with synthetic spin-orbit coupling.In particular,we focus on the pairing superfluidity in these systems at zero temperature.Recent studies have shown that different forms of spin-orbit coupling in various spatial dimensions can lead to a wealth of novel pairing superfluidity.A common theme of these variations is the emergence of new pairing mechanisms which are direct results of spin-orbit-coupling-modified single-particle dispersion spectra.As different configurations can give rise to single-particle dispersion spectra with drastic differences in symmetry,spin dependence and low-energy density of states,spin-orbit coupling is potentially a powerful tool of quantum control,which,when combined with other available control schemes in ultracold atomic gases,will enable us to engineer novel states of matter.展开更多
We investigate the features of the spontaneous emission spectra in a cold five-level atomic system coupled by a single elliptically polarized control field. We use wave function approach to derive the explicit and ana...We investigate the features of the spontaneous emission spectra in a cold five-level atomic system coupled by a single elliptically polarized control field. We use wave function approach to derive the explicit and analytical expressions of atomic spontaneous emission spectra. It is shown that some interesting phenomena such as spectralline enhancement, spectral-line suppression, spectral-line narrowing, spectral-line splitting and dark fluorescence can be observed in the spectra by appropriately modulating the phase difference between the right-hand circularly (LHC) and left-hand circularly (RHC) polarized components of the elliptically polarized control field and the intensity of external magnetic field. The number of emission peaks, the positions of fluorescence-quenching points can be also controlled. Furthermore, we propose an ultracold 87Rb atomic system for experimental observation. These investigations may find applications in high-precision spectroscopy.展开更多
基金supported by the Natural Science Foundation of Hunan Province under Grant No.06JJ50118
文摘We propose a scheme for realization a quantum Controlled-NOT gate operation using two four-level atoms through a selective atom cavity interaction in cavity quantum electrodynamics system. In our protocol, the quantum information is encoded on the stable ground states of the two atoms. During the interaction between atoms and single-mode vacuum cavity-field, the atomic spontaneous emission is negligible as the large atom-cavity detuning effectively suppresses the spontaneous decay of the atoms. The influences of the dissipation and the deviation of interaction time on fidelity and corresponding success probability of the quantum Controlled-NOT gate and the experimental feasibility of our proposal are also discussed.
基金Supported by Key Scientific Research Fund of Hunan Provincial Education Department of China under Grant No. 09A013Natural Science Foundation of Hunan Province of China under Grant No. 08J J3001Normal and Science Foundation of Hengyang Normal University of China under Grant No. 09A28
文摘A very simpJe theoretical scheme is proposed to implement two-and three-qubit controlled-phase gates firstly only using a single resonant interaction between ladder-type three-level atoms and the single-mode cavity. In the presented protocol, the quantum information is encoded on the stable ground states of the atoms （as the controlling qubits） and the zero- and one-photon Fock states of cavity-field （as the target qubit）. Under the influence of the atomic spontaneous emission, the decay of the cavity-mode, and deviation of the coupling strength, the three-qubit controlled- phase gate may have a comparatively high fidelity. The experimental feasibility of controlled-phase gate and the ease that is extended to realize N-qubit controlled-phase gate are also discussed.
文摘In recent years, we have entered a period of increasing impact of world affairs on national politics and international security. Notwithstanding, the present debate on national security and nuclear proliferation, Anglo-American ＂special relations＂ continue to be a subject of vigorous discussion influenced by the impact of new international emergencies as unstable countries acquire nuclear power and refuse ＂to reign＂ in their nuclear programmes （The Globe and Mail, 12 January 2012）. Along these lines the 71st anniversary of the Anglo-American Manhattan Project presents a unique opportunity to reappraise the Anglo-American wartime collaboration （or lack of） in atomic energy developments that resulted in the tragedy of nuclear weapons escalation. The Quebec Agreements of 1943-1944 were crafted to address the controlled flow of scientific information. But did this mean a trend toward more effective collaboration or toward greater American control of the atomic project？ This study explores the subject of nuclear politics from an unique vantage point of Anglo-Canadian and American-Canadian atomic diplomacy. In doing so, it will show that both the American and British atomic policy makers violated the Quebec Agreements. It seeks to demonstrate that （1） in the tangle of competition replacing cooperation, Canada was more important to the American atomic monopolists than the Anglo-AmcTican partnership, （2） the US-Canada Trade and Defence Agreements contributed to United States retaining exclusive control of the ＂absolute weapon＂, and that （3） their post-war nuclear energy agenda delayed Britain＇s atomic venture and isolated Britain from full participation in Arctic research. In practical terms, the emerging atomic policy in Washington boiled down to maintaining the American edge, come what may, and reducing British prestige in the post-war world. The article concludes by raising the question： did the United States, Britain, and Canada really work for atomic control？
文摘Parameters of the power source used to control PV-10 piezoelectric crystal valve are following DC output voltage： 0 - 120 V, continuously controllable, linear enlargement factor of input direct current voltage： approximate 25 times, the accuracy of DC output voltage： ±5%, manual control and automatic control.
文摘This study reports the synthesis of size-controlled Fe-MFI （Fe-substituted zeolites with the MFI topology） and their catalytic performances for DTO （dimethyl ether-to-olefins） reaction. The amount of HC1 and aging temperature were decisive factors to control the particle size of Fe-MFI in the range of 50 nm to 600 nm. The introduction of Fe3＋ ions into the zeolitic framework was confirmed by UV （ultraviolet）-visible spectroscopy. In addition, it was observed that the strength of acid site in prepared Fe-MFI was weaker than that of commercial ZSM-5. With decrease in the particle size, the amount of deposited coke decreased so that the catalyst life for the DTO reaction was well promoted. The present catalysts showed the higher light-olefin selectivity （C2= ＋ C3= ＋ C4=） than commercial ZSM-5 catalysts mainly due to the suppression of the formation of paraffins; however, the Fe-MFI catalysts were deactivated rapidly because of their low activity for the cracking of alkenes.
基金supported by National Fundamental Research Program of China(Grant Nos.2011CB921200 and 2011CBA00200)National Key Basic Research Program(Grant No.2013CB922000)+4 种基金National Natural Science Foundation(Grant No.60921091)National Science Foundation of China(Grant Nos.10904172,11104158,11374177,11105134,1127409and 11374283)the Fundamental Research Funds for the Central Universities(Grant No.WK2470000006)the Research Funds of Renmin University of China(Grant No.10XNL016)the programs of Chinese Academy of Sciences
文摘We review some recent progresses on the study of ultracold Fermi gases with synthetic spin-orbit coupling.In particular,we focus on the pairing superfluidity in these systems at zero temperature.Recent studies have shown that different forms of spin-orbit coupling in various spatial dimensions can lead to a wealth of novel pairing superfluidity.A common theme of these variations is the emergence of new pairing mechanisms which are direct results of spin-orbit-coupling-modified single-particle dispersion spectra.As different configurations can give rise to single-particle dispersion spectra with drastic differences in symmetry,spin dependence and low-energy density of states,spin-orbit coupling is potentially a powerful tool of quantum control,which,when combined with other available control schemes in ultracold atomic gases,will enable us to engineer novel states of matter.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11275047, 11004069 and 91021011the Doctoral Foundation of the Ministry of Education of China under Grant No.20100142120081the National Basic Research Program of China under Grant No.2012CB922103
文摘We investigate the features of the spontaneous emission spectra in a cold five-level atomic system coupled by a single elliptically polarized control field. We use wave function approach to derive the explicit and analytical expressions of atomic spontaneous emission spectra. It is shown that some interesting phenomena such as spectralline enhancement, spectral-line suppression, spectral-line narrowing, spectral-line splitting and dark fluorescence can be observed in the spectra by appropriately modulating the phase difference between the right-hand circularly (LHC) and left-hand circularly (RHC) polarized components of the elliptically polarized control field and the intensity of external magnetic field. The number of emission peaks, the positions of fluorescence-quenching points can be also controlled. Furthermore, we propose an ultracold 87Rb atomic system for experimental observation. These investigations may find applications in high-precision spectroscopy.
