We demonstrate site-resolved imaging of individual bosonic Yb 174 atoms in a Hubbard-regime twodimensional optical lattice with a short lattice constant of 266 nm. To suppress the heating by probe light with the 1 S 0 -1 P 1 transition of the wavelength λ=399 nm for high-resolution imaging and preserve atoms at the same lattice sites during the fluorescence imaging, we simultaneously cool atoms by additionally applying narrow-line optical molasses with the 1 S 0 -3 P 1 transition of the wavelength λ=556 nm. We achieve a low temperature of T 7.4 13 K ( ) m = , corresponding to a mean oscillation quantum number along the horizontal axes of 0.22(4) during the imaging process. We detect, on average, 200 fluorescence photons from a single atom within a 400 ms exposure time, and estimate a detection fidelity of 87(2)%. The realization of a quantum gas microscope with enough fidelity for Yb atoms in a Hubbard-regime optical lattice opens up the possibilities for studying various kinds of quantum many-body systems such as Bose and Fermi gases, and their mixtures, and also long-rangeinteracting systems such as Rydberg states.

eIF5B and eIF1A are two translation-initiation factors that are universally conserved among all kingdoms. They show a unique interaction in eukaryotes which is important for ribosomal subunit joining. Here, the structures of two isolated forms of yeast eIF5B and of the eIF5B-eIF1A complex (eIF1A and eIF5B do not contain the respective N-terminal domains) are reported. The eIF5B-eIF1A structure shows that the C-terminal tail of eIF1A binds to eIF5B domain IV, while the core domain of eIF1A is invisible in the electron-density map. Although the individual domains in all structures of eIF5B or archaeal IF5B (aIF5B) are similar, their domain arrangements are significantly different, indicating high structural flexibility, which is advantageous for conformational change during ribosomal subunit joining. Based on these structures, models of eIF5B, eIF1A and tRNAi(Met) on the 80S ribosome were built. The models suggest that the interaction between the eIF1A C-terminal tail and eIF5B helps tRNAi(Met) to bind to eIF5B domain IV, thus preventing tRNAi(Met) dissociation, stabilizing the interface for subunit joining and providing a checkpoint for correct ribosome assembly.

We observe magnetic Feshbach resonances in a collision between the ground and metastable states of two-electron atoms of ytterbium (Yb). We measure the on-site interaction of doubly occupied sites of an atomic Mott-insulator state in a three-dimensional optical lattice as a collisional frequency shift in a high-resolution laser spectroscopy. The observed spectra are well fitted by a simple theoretical formula, in which two particles with an s-wave contact interaction are confined in a harmonic trap. This analysis reveals a wide variation of the interaction with a resonance behavior around a magnetic field of about 1.1 G for the energetically lowest magnetic sublevel of 170Yb, as well as around 360 mG for the energetically highest magnetic sublevel of 174Yb. The observed Feshbach resonance can only be induced by an anisotropic interatomic interaction. This scheme will open the door to a variety of studies using two-electron atoms with tunable interaction.

Thick Si-doped AlN layers were homoepitaxially grown by hydride vapor phase epitaxy on AlN(0001) seed substrates. Following the removal of the seed substrate, an n-type AlN substrate with a carrier concentration of 2.4 × 1014 cm−3 was obtained. Vertical Schottky barrier diodes were fabricated by depositing Ni/Au Schottky contacts on the N-polar surface of the substrate. High rectification with a turn-on voltage of approximately 2.2 V was observed. The ideality factor of the diode at room temperature was estimated to be ∼8. The reverse breakdown voltage, defined as the leakage current level of 10−3 A/cm2, ranged from 550 to 770 V.

We successfully demonstrate a quantum gas microscopy using the Faraday effect which has an inherently non-destructive nature. The observed Faraday rotation angle reaches 3.0(2) degrees for a single atom. We reveal the non-destructive feature of this Faraday imaging method by comparing the detuning dependence of the Faraday signal strength with that of the photon scattering rate. We determine the atom distribution with deconvolution analysis. We also demonstrate the absorption and the dark field Faraday imaging, and reveal the different shapes of the point spread functions for these methods, which are fully explained by theoretical analysis. Our result is an important first step towards an ultimate quantum non-demolition site-resolved imaging and furthermore opens up the possibilities for quantum feedback control of a quantum many-body system with a single-site resolution.PACS numbers: 67.85. Hj, 07.60.Pb, 37.10.Jk, 78.20.Ls Measurement and manipulation of each single quantum object in a quantum many-body system lie at the heart of quantum information processing [1]. For ultracold atoms in an optical lattice, a technique of single-siteresolved imaging and single-site-addressing, called quantum gas microscope (QGM), is recently demonstrated for bosons [2][3][4][5] and fermions [6][7][8][9][10]. The development of QGM technique enables us to realize various fascinating experiments in the study of quantum many-body system [11][12][13][14][15][16], otherwise almost impossible to perform. In the currently developed QGM methods, however, atoms are measured by detecting fluorescent photons from atoms irradiated with near resonant probe light, resulting in the destruction of the quantum states of atoms such as internal spin states. In addition, the measurement inevitably induces considerable recoil heating, requiring elaborate cooling scheme in a deep optical lattice.An ultimate quantum measurement and control such as quantum non-demolition (QND) measurement and quantum feedback control is, on the one hand, demonstrated for a single mode of field state with a cavityquantum-electrodynamics (QED) system [17,18], for a collective spin ensemble by a dispersive atom-light interaction [19][20][21][22][23][24][25], and also for a superconducting quantum bit by a circuit QED system [26]. In order to realize an ultimate quantum measurement and control for each atom in an optical lattice, we need to develop a new detection method of QGM which does not rely on the destructive fluorescent measurement. Promising results along this line were already reported on the detection of a single atom trapped with a tightly-focused laser beam and a single ion in an ion-trap with a dispersive method in Ref.[27] and Ref. [28], respectively. Here we note that, although the use of an optical cavity provides an intriguing sensitivity for a single atom [29][30][31], this cannot be simply combined with a QGM technique because a cavity spatial mode determines the spatial resolution and therefore the single-site resolution is not expected.In this pap...

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A system of ultracold atoms in an optical lattice has been regarded as an ideal quantum simulator for a Hubbard model with extremely high controllability of the system parameters. While making use of the controllability, a comprehensive measurement across the weakly to strongly interacting regimes in the Hubbard model to discuss the quantum many-body state is still limited. Here we observe a great change in the excitation energy spectra across the two regimes in an atomic Bose–Hubbard system by using a spectroscopic technique, which can resolve the site occupancy in the lattice. By quantitatively comparing the observed spectra and numerical simulations based on sum rule relations and a binary fluid treatment under a finite temperature Gutzwiller approximation, we show that the spectra reflect the coexistence of a delocalized superfluid state and a localized insulating state across the two regimes.

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