We report on the first experimental realization of the controlled-not (cnot) quantum gate and entanglement for two individual atoms of different isotopes and demonstrate a negligible cross talk between two atom qubits. The experiment is based on a strong Rydberg blockade for ^{87}Rb and ^{85}Rb atoms confined in two single-atom optical traps separated by 3.8  μm. The raw fidelities of the cnot gate and entanglement are 0.73±0.01 and 0.59±0.03, respectively, without any corrections for atom loss or trace loss. Our work has applications for simulations of many-body systems with multispecies interactions, for quantum computing, and for quantum metrology.

The Zhaoshan long-baseline Atom Interferometer Gravitation Antenna (ZAIGA) is a new type of underground laser-linked interferometer facility, and is currently under construction. It is in the 200-meter-on-average underground of a mountain named Zhaoshan which is about 80 km southeast to Wuhan. ZAIGA will be equipped with long-baseline atom interferometers, high-precision atom clocks, and large-scale gyros. ZAIGA facility will take an equilateral triangle configuration with two 1-km-apart atom interferometers in each arm, a 300-meter vertical tunnel with atom fountain and atom clocks mounted, and a tracking-and-ranging 1-km-arm-length prototype with lattice optical clocks linked by locked lasers. The ZAIGA facility will be used for experimental research on gravitation and related problems including gravitational wave detection, high-precision test of the equivalence principle of micro-particles, clock based gravitational red-shift measurement, rotation measurement and gravito-magnetic effect. arXiv:1903.09288v4 [physics.atom-ph]

We report the creation of ultracold bosonic 23 Na 87 Rb Feshbach molecules via magneto-association. By ramping the magnetic field across an interspecies Feshbach resonance (FR), at least 4000 molecules can be produced out of the near degenerate ultracold mixture. Fast loss due to inelastic atom-molecule collisions is observed, which limits the pure molecule number, after residual atoms removal, to 1700. The pure molecule sample can live for 21.8(8) ms in the optical trap, long enough for future molecular spectroscopy studies toward coherently transferring to the singlet ro-vibrational ground state, where these molecules are stable against chemical reaction and have a permanent electric dipole moment of 3.3 Debye. We have also measured the Feshbach molecule's binding energy near the FR by the oscillating magnetic field method and found these molecules have a large closed-channel fraction.The creation and manipulation of ultracold heteronuclear molecules have received intensive attentions in recent years due to the versatile and promising potential applications [1, 2] of these molecules. With controllable, anisotropic and long range dipole-dipole interactions, they could be used in quantum computation [3,4], quantum simulation [5], precision measurement [6,7] and controlled cold chemistry [8]. So far, the most successful scheme for producing ultracold ground-state dipolar molecule is by associating ultracold atoms near Feshbach resonances (FRs) [9, 10] to form weakly-bound molecules first, followed by a stimulated Raman adiabatic rapid passage (STIRAP) [11] to transfer them to a deeply bound state [12,13]. This has been successfully applied to the 40 K 87 Rb system [14], where near degenerate ground-state dipolar fermionic molecules are created. However, the chemical reaction 2 KRb→ K 2 + Rb 2 is an exoergic process which results in a large inelastic loss, severely limiting the trap lifetime of the KRb molecular gas [15][16][17].Currently, there is a great effort in generalizing the KRb production scheme to other heteronuclear alkali dimers. Creation of Feshbach molecules of RbCs [18], LiNa [19] and NaK [20] were already reported in 2012, and very recently ground-state RbCs molecules were successfully produced [21,22]. In this work, we focus on the bosonic NaRb molecule, which in the absolute ground state is stable against chemical reactions [23] and has a permanent electric dipole moment as large as 3.3 Debye [24]. The ground-state NaRb molecule can be readily polarized with a moderate electric field. For instance, at 5 kV cm −1 the induced dipole moment is already more than 2 Debye. Therefore, it is an appealing system for studying the bosonic quantum gas with strong dipolar interactions. Recently, the double species Bose-Einstein condensates (BECs) of 23 Na and 87 Rb atoms have been produced [25] and their interspecies FRs [26] were also investigated in our group. One of the s-wave resonances between atoms in their lowest hyperfine Zeeman state locates conveniently at a magnetic field B 0 = 347.7 G with a width ...

We demonstrate trapping a single rubidium atom in a blue detuned optical bottle beam trap. The trap was formed by a strongly focused blue detuned laser beam, which passes through a computer-generated circular pi phase hologram displayed on a spatial light modulator. Single atoms were loaded from a magneto-optical trap and stored in the optical trap for several seconds.

The highly organized microstructure of dental enamel is a result of protein-guided anisotropic growth of apatite nanofibers. It is established that amelogenin proteins, the main constituent of the developing enamel matrix, form nanospheres in vitro, but the amphiphilic nature of the full-length protein conveys the possibility of generating more complex structures as observed with other surfactant-like molecules. This study tested if the use of metastable oil-water emulsions can induce supramolecular assemblies of amelogenin. Recombinant full-length amelogenin, rH174, was mixed into octanol/ethyl acetate preparations of different ratios to form emulsions at pH 4.5 and 7.4. Atomic force and electron microscopy showed the formation of 16.7±1.0 nm wide nanoribbons which grew to several micrometer length over a period of days. Nanoribbons formed from reverse micelles by enabling hydrophobic tails of the molecules to interact while preventing the formation of amelogenin nanospheres. Ribbon formation required the presence of calcium and phosphate ions and may be localized at a dark central line along the amelogenin ribbons. The ribbons have a strong tendency to align in parallel maintaining 5 to 20nm space between each other. The growth rates and number of ribbons were significantly higher at pH 4.5 and related to the metastability of the emulsion. A model for ribbon extension proposes the addition of short segments or amelogenin dimers to the ends of the ribbon. The formation of self-aligning and uniaxially elongating amelogenin structures triggered by the presence of calcium and phosphate may represent a suitable new model for protein controlled mineralization in enamel.

Abstract-This paper presents the design, simulation and measurement of a dual-band terahertz metamaterial absorber with polarization-insensitivity and wide incident angle. The unit cell of the metamaterial consists of top resonator structures and low metallic ground plane, separated by an isolation material spacer to realize both electric and magnetic resonances. The physical mechanism of dual-band absorption and the sensitivity to the polarization direction and incident direction of the EM wave are theoretically investigated by simulating the x-component and normal component electric field distribution, current distribution on ERRs and metallic ground plane, and distribution of power flow and loss at the resonance frequencies as well as different modes EM waves, based the FDTD calculated method, respectively. The results show that the absorber is not only correctly coupling to the incident electric field and magnetic field, but also can trap the input power into specific positions of the devices and absorb it, besides insensitivity to the polarized angle and incident angle. Moreover, the experiment demonstrates that the absorber achieves two strong absorptions of 82.8% and 86.8% near 1.724 and 3.557 THz.

We report the observation of coherent heteronuclear spin dynamics driven by inter-species spinspin interaction in an ultracold spinor mixture, which manifests as periodical and well correlated spin oscillations between two atomic species. In particular, we investigate the magnetic field dependence of the oscillations and find a resonance behavior which depends on both the linear and quadratic Zeeman effects and the spin-dependent interaction. We also demonstrate a unique knob for controlling the spin dynamics in the spinor mixture with species-dependent vector light shifts. Our finds are in agreement with theoretical simulations without any fitting parameters.

Here, a high sensitivity gas sensing ink based on sulfonated rGO (S-rGO) decorated with SnS 2 is synthesized for room temperature NO 2 and NH 3 detection. This sensing ink demonstrated an excellent sensitivity to ppb-level NO 2 (17% response to 125 ppb) and sub-ppm-level NH 3 (11% response to 1 ppm). The unique absorption properties of SnS 2 improve the sensitivity of S-rGO 4.2 and 55 times to NO 2 and NH 3 , respectively. Besides, the superhydrophobicity of the SnS 2 endows the sensor with exceptional immunity to high relative humidity (RH). Furthermore, the sensors exhibit negligible degradation to NO 2 and less than 15% degradation to NH 3 in a wide range of RH from 30 (ambient humidity) to 90%. More importantly, the obtained full-written ink can be applied to common substrates, such as glass, clothes, and paper, and maintain excellent performance after being bent and twisted by 180°.