The quantum behavior ofa precooled cantilever can be probed highly efficiently by electrostatically coupling to a trapped ultracold ion, in which a fast cooling of the cantilever down to the ground vibrational state ...The quantum behavior ofa precooled cantilever can be probed highly efficiently by electrostatically coupling to a trapped ultracold ion, in which a fast cooling of the cantilever down to the ground vibrational state is possible. Within a simple model with an ultracold ion coupled to a cantilever with only few vibrational quanta, we solve the dynamics of the coupling system by a squeezed-state expansion technique, and can in principle obtain the exact solution of the time-evolution of the coupling system in the absence of the rotating-wave approximation. Comparing to the treatment under the rotating-wave approximation, we present a more accurate description of the quantum behavior of the cantilever.展开更多
The Jaynes-Cummings model （JCM） is studied in the absence of the rotating-wave approximation （RWA） by a coherent-state expansion technique. In comparison with the previous paper in which the coherent-state expansi...The Jaynes-Cummings model （JCM） is studied in the absence of the rotating-wave approximation （RWA） by a coherent-state expansion technique. In comparison with the previous paper in which the coherent-state expansion was performed only to the third order, we carry out in this paper a complete expansion to demonstrate exactly the dynamics of the JCM without the RWA. Our study gives a systematic method to solve the non-RWA problem, which would be useful in various physical systems, e.g., in a system with an ultracold trapped ion experiencing the running waves of lasers.展开更多
The effect of double frequency oftrap fieldφ=U-V1 cosΩt-V2 cos 2Ωt in a Paul trap can be described exactly by using a function series expansion to solve the corresponding Mathieu equation.The stability regions of a...The effect of double frequency oftrap fieldφ=U-V1 cosΩt-V2 cos 2Ωt in a Paul trap can be described exactly by using a function series expansion to solve the corresponding Mathieu equation.The stability regions of a trapped ion are plotted and some meaningful physical results are shown.展开更多
The spatial manipulation of ionic qubits in a fast and precise fashion is one of the foremost issues in scalable quantum information processing with trapped ions.We report our recent efforts toward precise manipulatio...The spatial manipulation of ionic qubits in a fast and precise fashion is one of the foremost issues in scalable quantum information processing with trapped ions.We report our recent efforts toward precise manipulation of trapped ions,including separation,recombination and reordering of the ions,in our home-made microscopic surface-electrode trap.We also demonstrate the micromotion compensation for the trapped ions by rf-photon cross-correlation,which ensures the cooling of the ions down to the temperature 23.3 mK.展开更多
In this paper we try to develop a scalable surface-electrode architecture for ion trap quantum information processing.The confinement of the ions by the rf pseudopotential and the movement of the ions by changing the ...In this paper we try to develop a scalable surface-electrode architecture for ion trap quantum information processing.The confinement of the ions by the rf pseudopotential and the movement of the ions by changing the rf pseudopotential are investigated by numerical simulation.Particular concern is paid to the+-shaped junction,which is the connection of different components of the architecture,and also on the place which yields heat and escaping ions.We show the feasibility of fabricating and operating on the architecture for quantum information processing with currently available technology.展开更多
We propose a scheme to purify entanglement of two atoms from not-too-impure entangled states by checking the parity of the two atoms through the cavity input-output process. As the parity check is made by measurement ...We propose a scheme to purify entanglement of two atoms from not-too-impure entangled states by checking the parity of the two atoms through the cavity input-output process. As the parity check is made by measurement on single-photon polarization, which would not affect the entanglement of the two atoms, our scheme has the successful probability double of that in a previous well-known scheme with linear optical elements [Nature （London） 410 （2001） 1067], and is insensitive to the photon loss and the detection inefficieney. Experimental feasibility of our scheme with current technology is discussed.展开更多
^(40)Ca^(+) ions are successfully confined,under the cooling of a red-detuned laser,in a home-built microscopic surface-electrode(MSE)trap.With all electrodes deposited on a low-rf-loss substrate,our 500-μm-scale MSE...^(40)Ca^(+) ions are successfully confined,under the cooling of a red-detuned laser,in a home-built microscopic surface-electrode(MSE)trap.With all electrodes deposited on a low-rf-loss substrate,our 500-μm-scale MSE trap is designed involving three potential wells and manufactured by the standard technique of the printed circuit board.Both linear and two-dimensional crystals of ^(40)Ca^(+) are observed in the trap after preliminary micromotion compensation is carried out.The development of the MSE trap aims at large-scale trapped-ion quantum information processing.展开更多
We demonstrate experimentally the Doppler cooling of ^(40)Ca^(+) ions using the S_(1/2)→D_(3/2) electric quadrupole transition,in which the scattering light that is much different from the exciting light makes it pos...We demonstrate experimentally the Doppler cooling of ^(40)Ca^(+) ions using the S_(1/2)→D_(3/2) electric quadrupole transition,in which the scattering light that is much different from the exciting light makes it possible to collect background-free fluorescence.The idea excluding 397 nm excitation has the advantage of high-sensitivity detection and only employs lasers in red and infrared wavelengths,which should be practical for trapped-ion quantum information processing.展开更多
The stable confinement of ions in an electromagnetic trap is a prerequisite of sideband cooling and quantum information processing.For a string of ions in a linear ion trap,we report our recent efforts of compensating...The stable confinement of ions in an electromagnetic trap is a prerequisite of sideband cooling and quantum information processing.For a string of ions in a linear ion trap,we report our recent efforts of compensating for micromotion of the ions by three methods,which yields narrower fluorescence spectra and lower temperature.We also achieve a photoionization scheme that loads the ions deterministically into the linear trap from an atomic beam.展开更多
Superpositional wave function oscillations for the implementation of quantum algorithms modify the desired interference required for the quantum computation. We propose a scheme with trapped ultracold ion-pairs being ...Superpositional wave function oscillations for the implementation of quantum algorithms modify the desired interference required for the quantum computation. We propose a scheme with trapped ultracold ion-pairs being qubits to diminish the detrimental effect of the wave function oscillations, which is applied to the two-qubit Grover's search. It can be also found that the qubits in our scheme are more robust against the decoherence caused by the environment, and the model is scalable.展开更多
A scheme is presented for realizing quantum logic gate in an ion trap.In the scheme the state of the mth ion is Grst replicated onto the collective motion.Then a transformation,conditional on the motional state,is per...A scheme is presented for realizing quantum logic gate in an ion trap.In the scheme the state of the mth ion is Grst replicated onto the collective motion.Then a transformation,conditional on the motional state,is performed on the nth ion.Finally the motional state is replicated back onto the mth ion.By this way the quantum logic gate between the mth and the nth ions is realized.The scheme does not put any requirement on the Lamb-Dicke parameter.展开更多
The Schrödinger equation of two ultracold ions confined in xy plane of the Penning trap is exactly solved and the analytical form of the wave function of the system is obtained.A numerical calculation for a conti...The Schrödinger equation of two ultracold ions confined in xy plane of the Penning trap is exactly solved and the analytical form of the wave function of the system is obtained.A numerical calculation for a continued fraction presents the relation among the beigenenergies,the Coulomb interaction and the azimuthal number.展开更多
Taking two identical ions in a Paul trap,we solved the SchrÖdinger equation for one-,two-,and three-dimensional harmonically bound two-body Coulomb models,in which the eigenfunctions are written in a series form ...Taking two identical ions in a Paul trap,we solved the SchrÖdinger equation for one-,two-,and three-dimensional harmonically bound two-body Coulomb models,in which the eigenfunctions are written in a series form and the eigenenergies are obtained from a continued fraction.Numerical calculations are made for specific discussion of two-and three-dimensional case.The comparison with a former one-dimensional approximate work shows that our result is more general and accurate.展开更多
The energy levels and the E2 transition probabilities B(E2)of uranium isotopes ^(230-238)U are calculated by the 1/N expansion technique with the consistent Q framework in sdIBMl.The energy spectra for the five isotop...The energy levels and the E2 transition probabilities B(E2)of uranium isotopes ^(230-238)U are calculated by the 1/N expansion technique with the consistent Q framework in sdIBMl.The energy spectra for the five isotopes and B(E2)of ^(236)U can be reproduced quite well with a few number of parameters only.展开更多
A scheme of teleportation of two unknown quantum states via quantum computation is proposed.The comparison with the former proposals shows that our scheme is more in tune with the original teleportation proposal and t...A scheme of teleportation of two unknown quantum states via quantum computation is proposed.The comparison with the former proposals shows that our scheme is more in tune with the original teleportation proposal and the efficiency is higher.The teleportation of an unknown entangled state is also discussed.展开更多
The pulse sequences of the logic operations used in quantum discrete Fourier transform are designed for the experiment of nuclear magnetic resonance(NMR), and 2-qubit discrete Fourier transforms are implemented experi...The pulse sequences of the logic operations used in quantum discrete Fourier transform are designed for the experiment of nuclear magnetic resonance(NMR), and 2-qubit discrete Fourier transforms are implemented experimentally with NMR. The experimental errors are examined and methods for reducing the errors are proposed.展开更多
The motional trembling(‘zitterbewegung’)of a relativistic electron governed by Dirac equation was originally predicted by Schr¨odinger in the early days of quantum mechanics and simulated in a recent experiment...The motional trembling(‘zitterbewegung’)of a relativistic electron governed by Dirac equation was originally predicted by Schr¨odinger in the early days of quantum mechanics and simulated in a recent experiment with a single trapped ultracold ion.We investigate stable and instable confinements of a single trapped ion in a Paul trap under different conditions relevant to parity.Since our treatment involves neither restriction of Lamb-Dicke limit nor rotating-wave approximation,we may demonstrate different quantum dynamics of the single trapped ion in a wide range of the trapping parameters.We discuss the origin of the zitterbewegung which is relevant to the stability of the ion trapping.展开更多
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10474118 and 10274093 and the National Fundamental Research Program of China under Grant No. 2005CB724502
文摘The quantum behavior ofa precooled cantilever can be probed highly efficiently by electrostatically coupling to a trapped ultracold ion, in which a fast cooling of the cantilever down to the ground vibrational state is possible. Within a simple model with an ultracold ion coupled to a cantilever with only few vibrational quanta, we solve the dynamics of the coupling system by a squeezed-state expansion technique, and can in principle obtain the exact solution of the time-evolution of the coupling system in the absence of the rotating-wave approximation. Comparing to the treatment under the rotating-wave approximation, we present a more accurate description of the quantum behavior of the cantilever.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10474118 and 10274093, the National Fundamental Research Program of China under Grant No. 2005CB724502, and the Foundation from Educational Department of Sichuan Province of China under Grant No. 2004C017
文摘The Jaynes-Cummings model （JCM） is studied in the absence of the rotating-wave approximation （RWA） by a coherent-state expansion technique. In comparison with the previous paper in which the coherent-state expansion was performed only to the third order, we carry out in this paper a complete expansion to demonstrate exactly the dynamics of the JCM without the RWA. Our study gives a systematic method to solve the non-RWA problem, which would be useful in various physical systems, e.g., in a system with an ultracold trapped ion experiencing the running waves of lasers.
基金The project supported by National Natural Science Foundation of China under Grant Nos 19904013 and 1904014
文摘The effect of double frequency oftrap fieldφ=U-V1 cosΩt-V2 cos 2Ωt in a Paul trap can be described exactly by using a function series expansion to solve the corresponding Mathieu equation.The stability regions of a trapped ion are plotted and some meaningful physical results are shown.
基金Supported by the National Basic Research Program of China under Grant No 2012CB922102the National Natural Science Foundation of China under Grants Nos 11274352 and 11104325.
文摘The spatial manipulation of ionic qubits in a fast and precise fashion is one of the foremost issues in scalable quantum information processing with trapped ions.We report our recent efforts toward precise manipulation of trapped ions,including separation,recombination and reordering of the ions,in our home-made microscopic surface-electrode trap.We also demonstrate the micromotion compensation for the trapped ions by rf-photon cross-correlation,which ensures the cooling of the ions down to the temperature 23.3 mK.
基金Supported by the National Natural Science Foundation of China under Grant No 10974225the Fund from WIPM.
文摘In this paper we try to develop a scalable surface-electrode architecture for ion trap quantum information processing.The confinement of the ions by the rf pseudopotential and the movement of the ions by changing the rf pseudopotential are investigated by numerical simulation.Particular concern is paid to the+-shaped junction,which is the connection of different components of the architecture,and also on the place which yields heat and escaping ions.We show the feasibility of fabricating and operating on the architecture for quantum information processing with currently available technology.
基金supported by National Natural Science Foundation of China under Grant Nos.10774163,10774042,and 10747167the State Key Basic Research Program of China under Grant Nos.2005CB724502 and 2006CB921203
文摘We propose a scheme to purify entanglement of two atoms from not-too-impure entangled states by checking the parity of the two atoms through the cavity input-output process. As the parity check is made by measurement on single-photon polarization, which would not affect the entanglement of the two atoms, our scheme has the successful probability double of that in a previous well-known scheme with linear optical elements [Nature （London） 410 （2001） 1067], and is insensitive to the photon loss and the detection inefficieney. Experimental feasibility of our scheme with current technology is discussed.
基金Supported by the National Basic Research Program of China under Grant No 2012CB922102the National Natural Science Foundation of China under Grants Nos 10974225 and 11104325.
文摘^(40)Ca^(+) ions are successfully confined,under the cooling of a red-detuned laser,in a home-built microscopic surface-electrode(MSE)trap.With all electrodes deposited on a low-rf-loss substrate,our 500-μm-scale MSE trap is designed involving three potential wells and manufactured by the standard technique of the printed circuit board.Both linear and two-dimensional crystals of ^(40)Ca^(+) are observed in the trap after preliminary micromotion compensation is carried out.The development of the MSE trap aims at large-scale trapped-ion quantum information processing.
基金Supported by the National Basic Research Program of China under Grant No 2012CB922102the National Natural Science Foundation of China under Grant Nos 10974225,11104325。
文摘We demonstrate experimentally the Doppler cooling of ^(40)Ca^(+) ions using the S_(1/2)→D_(3/2) electric quadrupole transition,in which the scattering light that is much different from the exciting light makes it possible to collect background-free fluorescence.The idea excluding 397 nm excitation has the advantage of high-sensitivity detection and only employs lasers in red and infrared wavelengths,which should be practical for trapped-ion quantum information processing.
基金by the National Natural Science Foundation of China under Grant No 10974225.
文摘The stable confinement of ions in an electromagnetic trap is a prerequisite of sideband cooling and quantum information processing.For a string of ions in a linear ion trap,we report our recent efforts of compensating for micromotion of the ions by three methods,which yields narrower fluorescence spectra and lower temperature.We also achieve a photoionization scheme that loads the ions deterministically into the linear trap from an atomic beam.
基金Supported by the National Natural Science Foundation of China under Grant No.19904013.
文摘Superpositional wave function oscillations for the implementation of quantum algorithms modify the desired interference required for the quantum computation. We propose a scheme with trapped ultracold ion-pairs being qubits to diminish the detrimental effect of the wave function oscillations, which is applied to the two-qubit Grover's search. It can be also found that the qubits in our scheme are more robust against the decoherence caused by the environment, and the model is scalable.
基金Supported by the National Natural Science Foundation of China under Grant No.19734060.
文摘A scheme is presented for realizing quantum logic gate in an ion trap.In the scheme the state of the mth ion is Grst replicated onto the collective motion.Then a transformation,conditional on the motional state,is performed on the nth ion.Finally the motional state is replicated back onto the mth ion.By this way the quantum logic gate between the mth and the nth ions is realized.The scheme does not put any requirement on the Lamb-Dicke parameter.
基金Supported by the National Natural Science Foundation of China under Grant No.19604013.
文摘The Schrödinger equation of two ultracold ions confined in xy plane of the Penning trap is exactly solved and the analytical form of the wave function of the system is obtained.A numerical calculation for a continued fraction presents the relation among the beigenenergies,the Coulomb interaction and the azimuthal number.
基金Supported by the National Natural Science Foundation of China under Grant No.19404004。
文摘Taking two identical ions in a Paul trap,we solved the SchrÖdinger equation for one-,two-,and three-dimensional harmonically bound two-body Coulomb models,in which the eigenfunctions are written in a series form and the eigenenergies are obtained from a continued fraction.Numerical calculations are made for specific discussion of two-and three-dimensional case.The comparison with a former one-dimensional approximate work shows that our result is more general and accurate.
基金Supported by the National Natural Science Foundation of China。
文摘The energy levels and the E2 transition probabilities B(E2)of uranium isotopes ^(230-238)U are calculated by the 1/N expansion technique with the consistent Q framework in sdIBMl.The energy spectra for the five isotopes and B(E2)of ^(236)U can be reproduced quite well with a few number of parameters only.
基金Supported partly by the National Natural Science Foundation of China under Grant No.19734060,and the special support for the fundamental research by National Commit tee of Science and Technology of China.
文摘A scheme of teleportation of two unknown quantum states via quantum computation is proposed.The comparison with the former proposals shows that our scheme is more in tune with the original teleportation proposal and the efficiency is higher.The teleportation of an unknown entangled state is also discussed.
文摘The pulse sequences of the logic operations used in quantum discrete Fourier transform are designed for the experiment of nuclear magnetic resonance(NMR), and 2-qubit discrete Fourier transforms are implemented experimentally with NMR. The experimental errors are examined and methods for reducing the errors are proposed.
基金supported by the National Natural Science Foundation of China(Grant Nos.11274352 and 11274351)
文摘The motional trembling(‘zitterbewegung’)of a relativistic electron governed by Dirac equation was originally predicted by Schr¨odinger in the early days of quantum mechanics and simulated in a recent experiment with a single trapped ultracold ion.We investigate stable and instable confinements of a single trapped ion in a Paul trap under different conditions relevant to parity.Since our treatment involves neither restriction of Lamb-Dicke limit nor rotating-wave approximation,we may demonstrate different quantum dynamics of the single trapped ion in a wide range of the trapping parameters.We discuss the origin of the zitterbewegung which is relevant to the stability of the ion trapping.
