Physical Review Letters

We perform a quantitative analysis of extensive chess databases and show that the frequencies of opening moves are distributed according to a power law with an exponent that increases linearly with the game depth, whereas the pooled distribution of all opening weights follows Zipf’s law with unive...

Based on first-principles calculations, we demonstrate that magnetism impedes the formation of long chains in break junctions. We find a distinct softening of the binding energy of atomic chains due to the creation of magnetic moments that crucially reduces the probability of successful chain format...

Strained coherent film growth is commonly either limited to ultrathin films or low strains. Here, we present an approach to achieve high strains in thicker films, by using materials with inherent structural instabilities. As an example, 50 nm thick epitaxial films of the Fe₇₀Pd₃₀ magnetic shape mem...

A nonaxisymmetric stable magnetohydrodynamic (MHD) equilibrium within a prolate cylindrical conducting boundary has been produced experimentally. It has m=1 azimuthal symmetry, helical distortion, and flat λ profile, all in agreement with the computed magnetically relaxed minimum magnetic energy Ta...

We propose a method for optical nanoimaging in which the structure of a three-dimensional inhomogeneous medium may be recovered from far-field power measurements. Neither phase control of the illuminating field nor phase measurements of the scattered field are necessary. The method is based on the s...

We construct a general measure for the degree of non-Markovian behavior in open quantum systems. This measure is based on the trace distance which quantifies the distinguishability of quantum states. It represents a functional of the dynamical map describing the time evolution of physical states, an...

The charge flow from a single C₆₀ molecule to another one has been probed. The conformation and electronic states of both molecules on the contacting electrodes have been characterized using a cryogenic scanning tunneling microscope. While the contact conductance of a single molecule between two Cu ...

A variety of analytical techniques suggest that quantum fluctuations lead to a fundamental instability of the Fermi liquid that drives ferromagnetic transitions first order at low temperatures. We present both analytical and numerical evidence that, driven by the same quantum fluctuations, this firs...

We report Bose-Einstein condensation of ⁸⁴Sr in an optical dipole trap. Efficient laser cooling on the narrow intercombination line and an ideal s-wave scattering length allow the creation of large condensates (N₀∼3×10⁵) even though the natural abundance of this isotope is only 0.6%. Condensation...

We report on the attainment of Bose-Einstein condensation with ultracold strontium atoms. We use the ⁸⁴Sr isotope, which has a low natural abundance but offers excellent scattering properties for evaporative cooling. Accumulation in a metastable state using a magnetic-trap, narrowline cooling, and s...

We present a novel method to compute expectation values in the Lieb-Liniger model both at zero and finite temperature. These quantities, relevant in the physics of one-dimensional ultracold Bose gases, are expressed by a series that has a remarkable behavior of convergence. Among other results, we s...

We provide a feasible necessary and sufficient condition for when an unknown quantum operation (quantum device) secretly selected from a set of known quantum operations can be identified perfectly within a finite number of queries, and thus complete the characterization of the perfect distinguishabi...

Ultracompact minihalos have been proposed as a new class of dark matter structure. They would be produced by phase transitions in the early Universe or features in the inflaton potential, and constitute nonbaryonic massive compact halo objects today. We examine the prospects of detecting these minih...

We present an analysis of the decays B⁰→K^*0(892)γ and B⁺→K^*+(892)γ using a sample of about 383×10⁶ BB̅ events collected with the BABAR detector at the PEP-II asymmetric energy B factory. We measure the branching fractions B(B⁰→K^*0γ)=(4.47±0.10±0.16)×10^-5 and B(B⁺→K^*+γ)=(4.2...

To determine which nuclei may exhibit shape isomerism, we use a well-benchmarked macroscopic-microscopic model to calculate potential-energy surfaces as functions of spheroidal (ϵ₂), hexadecapole (ϵ₄), and axial-asymmetry (γ) shape coordinates for 7206 nuclei from A=31 to A=290. We analyze these ...

Fully differential data for H₂ dissociation in ultrashort (6 fs, 760 nm), linearly polarized, intense (0.44  PW/cm²) laser pulses with a stabilized carrier-envelope phase (CEP) were recorded with a reaction microscope. Depending on the CEP, the molecular orientation, and the kinetic energy rel...

We present experimental observations of strong electric and magnetic interactions between split ring resonators (SRRs) in metamaterials. We fabricated near-infrared planar metamaterials with different inter-SRR spacings along different directions. Our transmission measurements show blueshifts and re...

Identifying temporally invariant components in complex multivariate time series is key to understanding the underlying dynamical system and predict its future behavior. In this Letter, we propose a novel technique, stationary subspace analysis (SSA), that decomposes a multivariate time series into i...

The nonlinear wave pattern generated by a localized pressure source moving over a liquid free surface at speeds below the minimum phase speed (c_min⁡) of linear gravity-capillary waves is investigated experimentally and theoretically. At these speeds, freely propagating fully localized solitary wav...

We describe the breakup of a confined gas thread in a cross-flowing stream of liquid at capillary numbers Calt;10^-2. The breakup is initiated, not by a Plateau-Rayleigh instability, but by liquid that flows from the tip of the thread to the neck where pinch-off occurs. This flow, faster than previo...

Recent experiments have measured collisional frequency shifts in polarized fermionic alkaline-earth atoms using 1S0-3P0 Rabi spectroscopy. Here we provide a first-principles non-equilibrium theoretical description of the interaction frequency shifts starting from the microscopic many-body Hamiltonian. Our formalism describes the dependence of the frequency shift on excitation inhomogeneity, interactions,temperature, and many-body dynamics, provides a fundamental understanding of the effects of the measurement process, and explains the observed density shift data. We also propose a method to measure the second of the two 1S0-3P0 scattering lengths, whose knowledge is essential for quantum information processing and quantum simulation applications.

Optimal control theory is a promising candidate for adrastic improvement of the performance of quantum information tasks. We explore its ultimate limit in paradigmatic cases, and demonstrate that it coincides with the maximum speed limit allowed by quantum evolution.

I show that the usual model of the rotational response of a neutron star, which predicts rotation-induced neutronic vortices and no rotation-induced protonic vortices, does not hold (i) beyond a certain threshold of entrainment interaction strength nor (ii) in case of nonzero S- hyperon gap. I show that in both these cases the rotational response involves creation of phase windings in electrically charged condensate. Lattices of bound states of vortices which are caused these effects can (for a range of parameters) strongly reduce the interaction between rotation-induced vortices with magnetic-field carrying superconducting components.

Future weak lensing surveys will map the evolution of matter perturbations and gravitational potentials from the matter dominated epoch to today, yielding a new test of general relativity (GR) on cosmic scales. Along with constraining the expansion history, and thus the dark energy (DE) equation of state w(z), they will probe the relations between matter overdensities, local curvature, and the Newtonian potential. These relations, known in GR, can be modified in alternative gravity theories, or by the effects of massive neutrinos or exotic DE fluids. We introduce two functions of time and scale which account for any such modifications in the linear regime. We use a principal component analysis to find the eigenmodes of these functions that surveys like DES and LSST, along with CMB and SN data, will constrain. The number of constrained modes gives a model independent forecast of how many parameters describing deviations from GR could be constrained, along with w(z). The modes' scale and time dependence tell us which theoretical models will be better tested.

Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterises this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum -with turbulent fluctuations down by a factor of ~ 2 in power- provides a test of this invariance.

We present a direct measurement of the width of the W boson using the shape of the transverse mass distribution of \wen candidate events. Data from approximately 1 fb-1 of integrated luminosity recorded at s=1.96 TeV by the D0 detector at the Fermilab Tevatron p[`p] collider are analyzed. We use the same methods and data sample that were used for our recently published W boson mass measurement, except for the modeling of the recoil, which is done with a new method based on a recoil library. Our result, 2.028 0.072 GeV, is in agreement with the predictions of the standard model.

Excited states in 212Po were populated by a transfer using the 208Pb(18O, 14C) reaction and their deexcitation g-rays were studied with the Euroball array. Several levels were found to decay by a unique E1 transition (Eg < 1nbsp;MeV) populating the yrast state with the same spin value. Their lifetimes were measured by the DSAM method. The values, found in the range [0.1-1.4]nbsp;ps, lead to very enhanced transitions, B(E1) = 2times;10-2nbsp;-nbsp;1times;10-3 W.u.. These results are discussed in terms of an a-cluster structure which gives rise to states with non-natural parity values, provided that the composite system cannot rotate collectively, as expected in the 'a+208Pb' case. Such states due to the oscillatory motion of the a-core distance are observed for the first time.

A perfect invisibility cloak is commonly believed to be undetectable from electromagnetic (EM) detection because it is equivalent to a curved but empty EM space created from coordinate transformation. Based on the intrinsic asymmetry of coordinate transformation applied to motions of photons and charges, we propose a method to detect this curved EM space by shooting a fast moving charged particle through it. A broadband radiation generated in this process makes a cloak visible. Our method is the only known EM mechanism so far to detect an ideal perfect cloak (curved EM space) within its working band.

Interactions of nanoscale structures with fluids are of current interest both in the elucidation of fluid dynamics at these small scales, and in determining the ultimate performance of nanoelectromechanical systems outside of vacuum. We present a comprehensive study of nanomechanical damping in three gases (He, N2, CO2), and liquid CO2. Resonant dynamics in multiple devices of varying size and frequency, is measured over 10 decades of pressure (1 mPa - 20 MPa) using a specially built gas pressurization optical chamber and time-domain stroboscopic optical interferometry. The wide pressure range allows full exploration of the regions of validity of Newtonian and non-Newtonian flow damping models. Observing free molecular flow behavior extending above 1 atmosphere, we find a fluid relaxation time model to be valid throughout, but not beyond, the non-Newtonian regime, and a Newtonian flow vibrating spheres model to be valid in the viscous limit.

We report the study of femtosecond laser-induced air plasma fluorescence under the illumination of terahertz (THz) pulses. Semi-classical modeling and experimental verification indicate that time-resolved THz radiation-enhanced-emission-of-fluorescence (REEF) is dominated by the electron kinetics and electron-impact-excitation of gas molecules/ions. We demonstrate that the temporal waveform of the THz field could be retrieved from the transient enhanced fluorescence, making omni-directional, coherent detection available for THz time-domain spectroscopy.