For the first time, in-gas-cell laser spectroscopy study of the ${}^{57,59,63,65}\mathrm{Cu}$ isotopes has been performed using the 244.164 nm optical transition from the atomic ground state of copper. The nuclear magnetic dipole moments for ${}^{57,59,65}\mathrm{Cu}$ relative to that of ${}^{63}\mathrm{Cu}$ have been extracted. The new value for ${}^{57}\mathrm{Cu}$ of $\mu ({}^{57}\mathrm{Cu})=+2.582(7){\mu }_N$ is in strong disagreement with the previous literature value but in good agreement with recent theoretical and systematic predictions.

We report a demonstration and quantitative characterization of one-dimensional cavity cooling of a single trapped ${}^{88}\mathrm{Sr}^{+}$ ion in the resolved-sideband regime. We measure the spectrum of cavity transitions, the rates of cavity heating and cooling, and the steady-state cooling limit. The cavity cooling dynamics and cooling limit of 22.5(3) motional quanta, limited by the moderate coupling between the ion and the cavity, are consistent with a simple model [Phys. Rev. A 64, 033405 (2001)] without any free parameters, validating the rate equation model for cavity cooling.

We present experiments on slow shear flow in granular materials. Under appropriate conditions shear localizes in narrow shear zones. We demonstrate that when the shear zone crosses a material boundary, it refracts in accordance with Snell’s law in optics—an effect first found in simulations [Phys. Rev. Lett. 98, 018301 (2007)]. The shear zone is the one that minimizes the dissipation rate upon shearing, i.e., a manifestation of the principle of least dissipation. We have prepared the materials as to form a granular lens. Shearing through the lens is shown to give a very broad shear zone, which corresponds to fulfilling Snell’s law for a continuous range of paths through the cell.

We implement the proof of principle for the quantum walk of one ion in a linear ion trap. With a single-step fidelity exceeding 0.99, we perform three steps of an asymmetric walk on the line. We clearly reveal the differences to its classical counterpart if we allow the walker or ion to take all classical paths simultaneously. Quantum interferences enforce asymmetric, nonclassical distributions in the highly entangled degrees of freedom (of coin and position states). We theoretically study and experimentally observe the limitation in the number of steps of our approach that is imposed by motional squeezing. We propose an altered protocol based on methods of impulsive steps to overcome these restrictions, allowing to scale the quantum walk to many, in principal to several hundreds of steps.

We report the observation of Sommerfeld-Brillouin optical precursors generated from a long square-modulated laser pulse propagating through a cold atomic ensemble with electromagnetically induced transparency. The optical depth (${\alpha }_{0}L$) of the medium can be varied from 0 up to 50. We demonstrated that the step-on rising and step-off falling edges propagate with the speed of light in vacuum without a slow light effect. At high ${\alpha }_{0}L$, the precursor is separated from the delayed main pulse at the rising edge, while at the falling edge, we observe damped oscillatory structures resulting from the interference between the precursor and main field.

We report results from a search for strangelets (small chunks of strange quark matter) in lunar soil using the Yale WNSL accelerator as a mass spectrometer. We have searched over a range in mass from $A=42$ to $A=70\mathrm{amu}$ for nuclear charges 5, 6, 8, 9, and 11. No strangelets were found in the experiment. For strangelets with nuclear charge 8, a concentration in lunar soil higher than ${10}^{-16}$ is excluded at the 95% confidence level. The implied limit on the strangelet flux in cosmic rays is the most sensitive to date for the covered range and is relevant to both recent theoretical flux predictions and a strangelet candidate event found by the AMS-01 experiment.

The fluctuation-dissipation theorem is a central result of statistical physics, which applies to any system at thermodynamic equilibrium. Its violation is a strong signature of nonequilibrium behavior. We show that for any system with Markovian dynamics, in a nonequilibrium steady state, a proper choice of observables restores a fluctuation-response theorem identical to a suitable version of the equilibrium fluctuation-dissipation theorem. This theorem applies to a broad class of dynamical systems. We illustrate it with linear stochastic dynamics and examples borrowed from the physics of molecular motors and Hopf bifurcations. Finally, we discuss general implications of the theorem.

Recently Hořava proposed a nonrelativistic renormalizable theory of gravitation, which reduces to Einstein’s general relativity at large distances, and that may provide a candidate for a UV completion of Einstein’s theory. In this Letter, we derive the full set of equations of motion, and then we obtain spherically symmetric solutions and discuss their properties. We also obtain solutions for the Friedmann-Lemaître-Robertson-Walker cosmological metric.

We report observation of the electroweak production of single top quarks in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ based on $2.3{\mathrm{fb}}^{-1}$ of data collected by the D0 detector at the Fermilab Tevatron Collider. Using events containing an isolated electron or muon and missing transverse energy, together with jets originating from the fragmentation of $b$ quarks, we measure a cross section of $\sigma (p\overline{p}\to tb+X,tqb+X)=3.94\pm 0.88\mathrm{pb}$. The probability to measure a cross section at this value or higher in the absence of signal is $2.5\times {10}^{-7}$, corresponding to a 5.0 standard deviation significance for the observation.

We report the observation of single top-quark production using $3.2{\mathrm{fb}}^{-1}$ of $p\overline{p}$ collision data with $\sqrt{s}=1.96\mathrm{TeV}$ collected by the Collider Detector at Fermilab. The significance of the observed data is 5.0 standard deviations, and the expected sensitivity for standard model production and decay is in excess of 5.9 standard deviations. Assuming $m_t=175\mathrm{GeV}/c^2$, we measure a cross section of ${2.3}_{-0.5}^{+0.6}(\mathrm{stat}+\mathrm{syst})\mathrm{pb}$, extract the CKM matrix-element value $|V_{tb}|=0.91\pm 0.11(\mathrm{stat}+\mathrm{syst})\pm 0.07(\mathrm{\text{theory}})$, and set the limit $|V_{tb}|>0.71$ at the 95% C.L.

We demonstrate single-site addressability in a two-dimensional optical lattice with 600 nm lattice spacing. After loading a Bose-Einstein condensate in the lattice potential, we use a focused electron beam to remove atoms from selected sites. The patterned structure is subsequently imaged by means of scanning electron microscopy. This technique allows one to create arbitrary patterns of mesoscopic atomic ensembles. We find that the patterns are remarkably stable against tunneling diffusion. Such microengineered quantum gases are a versatile resource for applications in quantum simulation, quantum optics, and quantum information processing with neutral atoms.

We propose the use of a superconducting transmission line formed from an array of direct-current superconducting quantum interference devices for investigating analogue Hawking radiation. Biasing the array with a space-time varying flux modifies the propagation velocity of the transmission line, leading to an effective metric with a horizon. Being a fundamentally quantum mechanical device, this setup allows for investigations of quantum effects such as backreaction and analogue space-time fluctuations on the Hawking process.

We develop the continuum mechanics of quantum many-body systems in the linear response regime. The basic variable of the theory is the displacement field, for which we derive a closed equation of motion under the assumption that the time-dependent wave function in a locally comoving reference frame can be described as a geometric deformation of the ground-state wave function. We show that this equation of motion is exact for systems consisting of a single particle, and for all systems at sufficiently high frequency, and that it leads to an excitation spectrum that has the correct integrated strength. The theory is illustrated by simple model applications to one- and two-electron systems.

The arrow-of-time dilemma states that the laws of physics are invariant for time inversion, whereas the familiar phenomena we see everyday are not (i.e., entropy increases). I show that, within a quantum mechanical framework, all phenomena which leave a trail of information behind (and hence can be studied by physics) are those where entropy necessarily increases or remains constant. All phenomena where the entropy decreases must not leave any information of their having happened. This situation is completely indistinguishable from their not having happened at all. In the light of this observation, the second law of thermodynamics is reduced to a mere tautology: physics cannot study those processes where entropy has decreased, even if they were commonplace.

We describe the construction of the complete four-loop four-particle amplitude of $\mathcal{N}=8$ supergravity. The amplitude is ultraviolet finite, not only in four dimensions, but in five dimensions as well. The observed extra cancellations provide additional nontrivial evidence that $\mathcal{N}=8$ supergravity in four dimensions may be ultraviolet finite to all orders of perturbation theory.

Some microorganisms, such as spermatozoa, synchronize their flagella when swimming in close proximity. Using a simplified model (two infinite, parallel, two-dimensional waving sheets), we show that phase locking arises from hydrodynamics forces alone, and has its origin in the front-back asymmetry of the geometry of their flagellar waveform. The time evolution of the phase difference between coswimming cells depends only on the nature of this geometrical asymmetry, and microorganisms can phase lock into conformations which minimize or maximize energy dissipation.

Atomic parity violation has been observed in the $6s^2{}^{1}S_0\to 5d6s{}^{3}D_1$ 408-nm forbidden transition of ytterbium. The parity-violating amplitude is found to be 2 orders of magnitude larger than in cesium, where the most precise experiments to date have been performed. This is in accordance with theoretical predictions and constitutes the largest atomic parity-violating amplitude yet observed. This also opens the way to future measurements of neutron distributions and anapole moments by comparing parity-violating amplitudes for various isotopes and hyperfine components of the transition.

We present an experimental study of the thermodynamics of free, size-selected water cluster anions consisting of 48 and 118 molecules. The measured caloric curves of the clusters are bulklike at low temperatures but show a well-defined, particle-size specific transition at $93\pm 3\mathrm{K}$ for $({\mathrm{H}}_2\mathrm{O}{)}_{48}^{-}$ and $118\pm 3\mathrm{K}$ for $({\mathrm{H}}_2\mathrm{O}{)}_{118}^{-}$. At the transition temperature the heat capacity strongly increases, which marks the onset of melting.

We present a solution to a long-standing basic problem encountered in the theory of structure determination of crystalline media from x-ray diffraction experiments; namely, the problem of determining phases of the diffracted beams.

The momentum transfer $\Delta k$ required for a photon to scatter from a target and emerge as a ${\rho }^0$ decreases as the photon energy $k$ rises. For $k>3\times {10}^{14}\mathrm{eV}$, $\Delta k$ is small enough that the interaction cannot be localized to a single nucleus. At still higher energies, photons may coherently scatter elastically from bulk matter and emerge as a ${\rho }^0$, in a manner akin to kaon regeneration. Constructive interference from the different nuclei coherently raises the cross section and the interaction probability rises linearly with energy. At energies above ${10}^{23}\mathrm{eV}$, coherent conversion is the dominant process; photons interact predominantly as ${\rho }^0$. We compute the coherent scattering probabilities in slabs of lead, water, and rock, and discuss the implications of the increased hadronic interaction probabilities for photons on ultrahigh energy shower development.