We report the observation of tunable spin-orbit coupling (SOC) for ultracold $^{87}$Rb atoms in hyperfine spin-1 states. Different from most earlier experiments where atomic SOC pseudo-spin-1/2 are synthesized with Raman lasers, scheme we demonstrate employs a gradient magnetic field (GMF) ground state and is immune to spontaneous emission. The effect confirmed through studies of: 1) collective dipole oscillation an condensate harmonic trap after abruptly turned on; 2) minimum energy at...

Based upon an over-one-month frequency comparison of two $^{40}{\mathrm{Ca}}^{+}$ optical clocks, the difference between clocks is measured to be $3.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$ with a measurement uncertainty $5.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$, considering both statistic ($1.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$) and systematic ($5.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$) uncertainties. This...

We propose how to prepare four remote logical qubits, with each in a separate cavity and encoded the decoherence-free subspace by two atoms, into various entangled states. By means of cavity-assisted photon scattering, we can link qubits different cavities be, respectively, $W$ state, Greenberger-Horne-Zeilinger cluster which are important view distributed quantum information processing. The generation latter states be theoretically generalized many-qubit cases. Because our defined...

We propose schemes to create cluster states and $W$ by many superconducting quantum-interference-device qubits in cavities under the influence of cavity decay. Our do not require auxiliary qubits, excited levels are only virtually coupled throughout scheme, which could much reduce experimental challenge. consider decay our model analytically demonstrate its detrimental on prepared entangled states.

We report a frequency measurement of the clock transition single ^40Ca^+ ion trapped and laser cooled in miniature ring Paul trap with 10^-15 level uncertainty. In measurement, we used an optical comb referenced to Hydrogen maser, which was calibrated SI second through Global Positioning System (GPS). Two rounds measurements were taken May June 2011, respectively. The measured be 411 042 129 776 393.0(1.6) Hz fractional uncertainty 3.9{\times}10^-15 total averaging time > 2{\times}10^6 s...

We determine the phase diagram of strongly correlated fermions in crossover from Bose-Einstein condensates molecules (BEC) to Cooper pairs (BCS) utilizing an artificial neural network. By applying advanced image recognition techniques momentum distribution fermions, a quantity which has been widely considered as featureless for providing information about condensed state, we measure critical temperature and show that it exhibits maximum on bosonic side crossover. Additionally, backanalyze...

A simple scheme is proposed to generate an $n$-qubit $W$ state in cavity QED. Conditioned on no photon leakage from the cavity, can be generated by resonant interaction between atoms and if initially prepared single-photon all are ground states. We check time evolution of system involving decay, show that, since required very short, with present QED techniques, success probability our almost unity.

In this paper, cooperative self-assembly (CSA) of colloidal spheres with different sizes was studied. It found that a complicated jamming effect makes it difficult to achieve an optimal self-assembling condition for construction well-ordered stacking in relatively short growth time by CSA. Through the use characteristic infrared (IR) technique significantly accelerate local evaporation on growing interface without changing bulk environment, concise three-parameter (temperature, pressure, and...

We recently reported a $^{40}{\mathrm{Ca}}^{+}$ optical clock comparison with an uncertainty at $5.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$, mainly limited by the excess micromotion shift. Here we report progress made to reduce this shift and its below $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}18}$ precise measurement of ``magic'' rf drive frequency ${\mathrm{\ensuremath{\Omega}}}_{0}$ which micromotion-induced scalar Stark second-order Doppler cancel each...

A simple scheme is presented to generate $N$-qubit $W$ states with rf superconducting quantum interference devices (SQUIDs) in cavity QED through adiabatic passage. Because of the achievable strong coupling for SQUID qubits embedded QED, we can get desired state high success probability. Furthermore, insensitive position inaccuracy SQUID. Numerical simulation shows that, by using present experimental techniques, achieve our very probability, and fidelity could eventually be unity help dissipation.

By virtue of single-photon interference, we present how to realize a nonlocal $N$-qubit conditional phase gate, which might be quite useful for the synthesis arbitrary entangled quantum states remote qubits required by distributed information processing. Without considering photon loss, our scheme would work in repeat-until-success fashion with an automatic feedback line added. Even taking loss into consideration, only success probability is affected, not gate fidelity.

Quantum cluster states and entangled-state analyzers are essential to measurement-based quantum computing. We propose generate a state make multipartite entanglement analyzer by using noninteracting free electrons or conduction in dots, based on polarizing beam splitters, charge detectors, single-spin rotations. Our schemes deterministic without the need of qubit-qubit interaction.

In this paper, we present a detailed method for rapidly and effectively loading single 40Ca+ ion into miniature linear Paul trap. Calcium atoms are generated by laser ablation, the is loaded specific isotopes selected two-step photo-ionization method. Compared to traditional in which typically emitted from resistively heated oven, advantages of ablation that it can be precisely controlled, avoid problem fluxed calcium deposition on trap electrodes, restricts generation dark ions, influence...

Following the proposal by F. Yamaguchi et al.[Phys. Rev. A 66, 010302 (R) (2002)], we present an alternative way to implement two-qubit Grover search algorithm in cavity QED. Compared with al.'s proposal, a strong resonant classical field added, our method is insensitive both decay and thermal field, doesn't require that remain vacuum state throughout procedure. Moreover, qubit definitions are same for atoms, which makes experiment easier. The strictly numerical simulation shows good enough...

Recent work is presented on the development of an optical frequency standard, based /sup 2/S/sub 1/2/-/sup 2/D/sub 5/2/ "clock" transition at 674 nm in two isotopes strontium. A/spl ap/200 Hz linewidth laser has been frequency-stabilised to centre 88/Sr/sup +/ ions, separately confined RF traps. The locking algorithm for control using ions described. mean difference observed 34(33) Hz, where number parenthesis standard uncertainty. Allan deviation stability was range from 10 50 30 s. In...

The hyperfine structure of the ${}^{2}{S}_{1/2}{\ensuremath{-}}^{2}{D}_{5/2}$ quadrupole transition at 674 nm in ${}^{87}{\mathrm{Sr}}^{+}$ has been observed. ion was confined a Paul trap and cooled using laser radiation 422 1092 nm. observed by monitoring quantum jumps 422-nm fluorescence. odd isotope strontium ``clock'' transitions independent first-order Zeeman shift ${}^{2}{D}_{5/2}$ state constants have determined as ${A}_{{D}_{5/2}}=2.1743(14)\mathrm{MHz}$...

We present a high-precision measurement of the $3d\phantom{\rule{4pt}{0ex}}^{2}D_{3/2}$--state lifetime in single trapped $^{40}\mathrm{Ca}^{+}$. The was performed using high-efficiency quantum-state detection technique to monitor quantum jumps and highly synchronous sequence for laser control. A feature our is pumping rate 729-nm that corrected real-time way. obtained through spontaneous decay after incoherent shelving ion $3d\phantom{\rule{4pt}{0ex}}^{2}D_{3/2}$ state with wait time....

In situ observations of evaporation-induced colloidal self-assembly and in measurement mass transfer process were carried out under a temperature pressure controlling system. The growth processes crystals different cuvettes recorded by direct video revealed that solvent flow around the pore space crystal played key role. By changing circumstances (temperature pressure) system properties fluid (viscosity), evaporation rate measured directly. It turned both as functions fit Stefan's law well....

We report the first experimental determination of $4s \ ^{2}S_{1/2} $ $\leftrightarrow $3d ^{2}D_{5/2}$ quadrupole transition matrix element in $^{40}$Ca$^+$ by measuring branching ratio ^{2}D_{5/2} state decaying into ground and lifetime state, using a technique highly synchronized measurement sequence for laser control efficient quantum detection jumps. The measured improved are, respectively, 0.9992(80) 1.1652(46) s, which yield value (in absolute value) 9.737(43)~$ea_{0}^{2}$ with...

Ultracold quantum gases are usually prepared in conservative traps for simulation experiments. The atomic density inhomogeneity, together with the consequent position-dependent energy and time scales of cold atoms traditional harmonic traps, makes it difficult to manipulate detect sample at a higher level. These problems partially solved by optical box made blue-detuned hollow beams. However, generating high-quality beam high light efficiency trap is challenging. Here, we present scheme that...

Recent progresses on quantum control of cold atoms and trapped ions in both the scientific technological aspects greatly advance applications precision measurement. Thanks to exceptional controllability versatility these massive systems, unprecedented sensitivity has been achieved clocks, magnetometers interferometers based ions. Besides, systems also feature many characteristics that can be employed facilitate different scenarios. In this review, we briefly introduce principles optical atom...

The authors investigate the response of a strongly-interacting superfluid Fermi gas to spin-flip and corresponding change interaction strength. They observe decay revival condensed fraction shape oscillations gas.