We explore the stability of flapping flight in a model system that consists of a pyramid-shaped object hovering in a vertically oscillating airflow. Such a flyer not only generates sufficient aerodynamic force to keep aloft but also robustly maintains balance during free flight. Flow visualization r...

[Phys. Rev. Lett. 108, 068103] Published Thu Feb 09, 2012

Synchronized oscillations are of critical functional importance in many biological systems. We show that such oscillations can arise without centralized coordination in a disordered system of electrically coupled excitable and passive cells. Increasing the coupling strength results in waves that lea...

[Phys. Rev. Lett. 108, 068102] Published Thu Feb 09, 2012

We observe that photon cooling after big bang nucleosynthesis but before recombination can remove the conflict between the observed and theoretically predicted value of the primordial abundance of ⁷Li. Such cooling is ordinarily difficult to achieve. However, the recent realization that dark matter ...

[Phys. Rev. Lett. 108, 061304] Published Thu Feb 09, 2012

In rhombohedral CaMn₇O₁₂, an improper ferroelectric polarization of magnitude 2870  μC m^-2 is induced by an incommensurate helical magnetic structure that evolves below T_N1=90  K. The electric polarization was found to be constrained to the high symmetry threefold rotation axis of the crystal struc...

[Phys. Rev. Lett. 108, 067201] Published Mon Feb 06, 2012

From detailed angle-resolved NMR and Meissner measurements on a ferromagnetic (FM) superconductor UCoGe (T_Curie∼2.5  K and T_SC∼0.6  K), we show that superconductivity in UCoGe is tightly coupled with longitudinal FM spin fluctuations along the c axis. We found that magnetic fields along the c axis (...

[Phys. Rev. Lett. 108, 066403] Published Mon Feb 06, 2012

When a star is tidally disrupted by a supermassive black hole (SMBH), the streams of liberated gas form an accretion disk after their return to pericenter. We demonstrate that Lense-Thirring precession in the spacetime around a rotating SMBH can produce significant time evolution of the disk angular...

[Phys. Rev. Lett. 108, 061302] Published Mon Feb 06, 2012

Efflorescence refers to crystallized salt structures that form at the surface of a porous medium. The challenge is to understand why these structures do not form everywhere at the surface of the porous medium but at some specific locations and why there exists an exclusion distance around an efflore...

[Phys. Rev. Lett. 108, 054502] Published Fri Feb 03, 2012

The Nernst coefficient for the quasi-one-dimensional metal, Li_0.9Mo₆O₁₇, is found to be among the largest known for metals (ν≃500  μV/KT at T∼20  K), and is enhanced in a broad range of temperature by orders of magnitude over the value expected from Boltzmann theory for carrier diffusion. A comparat...

[Phys. Rev. Lett. 108, 056604] Published Thu Feb 02, 2012

We observed, for the first time, solar neutrinos in the 1.0–1.5 MeV energy range. We determined the rate of pep solar neutrino interactions in Borexino to be 3.1±0.6_stat±0.3_syst  counts/(day·100  ton). Assuming the pep neutrino flux predicted by the standard solar model, we obtained a constraint on ...

[Phys. Rev. Lett. 108, 051302] Published Thu Feb 02, 2012

Inferring on the geometry of an object from its frequency spectrum is highly appealing since the object could then be imaged noninvasively or from a distance (as famously put by Kac, “can one hear the shape of a drum?”). In nuclear magnetic resonance of porous systems, the shape of the drum is repre...

[Phys. Rev. Lett. 108, 058103] Published Tue Jan 31, 2012

The first direct mass measurement of ⁶He has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the mass of ⁸He was determined with improved precision over our previous measurement. The obtained masses are m(⁶He)=6.018 885 883(57)  u and m(⁸He)=8.033 934 ...

[Phys. Rev. Lett. 108, 052504] Published Tue Jan 31, 2012

We show results on the vortex core dissipation through current-voltage measurements under applied pressure and magnetic field in the superconducting phase of CeCoIn₅. We find that as soon as the system becomes superconducting, the vortex core resistivity increases sharply as the temperature and magn...

[Phys. Rev. Lett. 108, 056401] Published Mon Jan 30, 2012

Despite the sphericity of the collapsing stellar core, the birth conditions of neutron stars can be highly nonspherical due to a hydrodynamical instability of the shocked accretion flow. Here we report the first laboratory experiment of a shallow water analogue, based on the physics of hydraulic jum...

[Phys. Rev. Lett. 108, 051103] Published Mon Jan 30, 2012

We demonstrate that 100% light absorption can take place in a single patterned sheet of doped graphene. General analysis shows that a planar array of small particles with losses exhibits full absorption under critical-coupling conditions provided the cross section of each individual particle is comp...

[Phys. Rev. Lett. 108, 047401] Published Fri Jan 27, 2012

A classical one-time pad allows two parties to send private messages over a public classical channel—an eavesdropper who intercepts the communication learns nothing about the message. A quantum one-time pad is a shared quantum state which allows two parties to send private messages or private quantu...

[Phys. Rev. Lett. 108, 040504] Published Fri Jan 27, 2012

We investigate the lifetime of two-electron spin states in a few-electron Si/SiGe double dot. At the transition between the (1,1) and (0,2) charge occupations, Pauli spin blockade provides a readout mechanism for the spin state. We use the statistics of repeated single-shot measurements to extract t...

[Phys. Rev. Lett. 108, 046808] Published Thu Jan 26, 2012

We demonstrate experimentally the production of Rydberg positronium (Ps) atoms in a two-step process, comprising incoherent laser excitation, first to the 2 ³P state and then to states with principal quantum numbers ranging from 10 to 25. We find that excitation of 2 ³P atoms to Rydberg levels occur...

[Phys. Rev. Lett. 108, 043401] Published Thu Jan 26, 2012

Charge radii of all magnesium isotopes in the sd shell have been measured, revealing evolution of the nuclear shape throughout two prominent regions of assumed deformation centered on ²⁴Mg and ³²Mg. A striking correspondence is found between the nuclear charge radius and the neutron shell structure....

[Phys. Rev. Lett. 108, 042504] Published Thu Jan 26, 2012

We analyze the temperature dependence of CP violation effects in the standard model by determining the effective action of its bosonic fields, obtained after integrating out the fermions from the theory and performing a covariant gradient expansion. We find nonvanishing CP violating terms starting a...

[Phys. Rev. Lett. 108, 041601] Published Thu Jan 26, 2012

We study analytically the order statistics of a time series generated by the positions of a symmetric random walk of n steps with step lengths of finite variance σ². We show that the statistics of the gap d_k,n=M_k,n-M_k+1,n between the kth and the (k+1)th maximum of the time series becomes stationary,...

[Phys. Rev. Lett. 108, 040601] Published Thu Jan 26, 2012

We introduce a “water retention” model for liquids captured on a random surface with open boundaries and investigate the model for both continuous and discrete surface heights 0,1,…,n-1 on a square lattice with a square boundary. The model is found to have several intriguing features, including a no...

[Phys. Rev. Lett. 108, 045703] Published Wed Jan 25, 2012

The current emission noise of a carbon nanotube quantum dot in the Kondo regime is measured at frequencies ν of the order or higher than the frequency associated with the Kondo effect k_BT_K/h, with T_K the Kondo temperature. The carbon nanotube is coupled via an on-chip resonant circuit to a quantum n...

[Phys. Rev. Lett. 108, 046802] Published Tue Jan 24, 2012

Evidence for the neutron-rich hypernucleus _Λ⁶H is presented from the FINUDA experiment at DAΦNE, Frascati, studying (π⁺,π^-) pairs in coincidence from the K_stop^-+⁶Li→_Λ⁶H+π⁺ production reaction followed by _Λ⁶H→⁶He+π^- weak decay. The production rate of _Λ⁶H undergoing this two-body π^- decay is determine...

[Phys. Rev. Lett. 108, 042501] Published Tue Jan 24, 2012

In supersymmetric theories with a strong conformal sector, soft supersymmetry breaking at the TeV scale naturally gives rise to confinement and chiral symmetry breaking at the same scale. We consider two such scenarios, one where the strong dynamics induces vacuum expectation values for elementary H...

[Phys. Rev. Lett. 108, 041802] Published Tue Jan 24, 2012

On the example of exceptional families of viruses we (i) show the existence of a completely new type of matter organization in nanoparticles, in which the regions with a chiral pentagonal quasicrystalline order of protein positions are arranged in a structure commensurate with the spherical topology...

[Phys. Rev. Lett. 108, 038102] Published Thu Jan 19, 2012

Entanglement and nonlocality are both fundamental aspects of quantum theory, and play a prominent role in quantum information science. The exact relation between entanglement and nonlocality is, however, still poorly understood. Here we make progress in this direction by showing that, contrary to wh...

[Phys. Rev. Lett. 108, 030403] Published Thu Jan 19, 2012

We address the fundamental question: how are pair correlations and structure factors of hard-sphere fluids affected by confinement between hard planar walls at close distance? For this purpose, we combine x-ray scattering from colloid-filled nanofluidic channel arrays and first-principles inhomogene...

[Phys. Rev. Lett. 108, 037802] Published Wed Jan 18, 2012

We report the first observations of the spin-singlet bottomonium states h_b(1P) and h_b(2P). The states are produced in the reaction e⁺e^-→h_b(nP)π⁺π^- using a 121.4  fb^-1 data sample collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e⁺e^- collider. We de...

[Phys. Rev. Lett. 108, 032001] Published Wed Jan 18, 2012

Sequences of alternating-sign time-dependent electric field pulses lead to coherent interference effects in Schwinger vacuum pair production, producing a Ramsey interferometer, an all-optical time-domain realization of the multiple-slit interference effect, directly from the quantum vacuum. The inte...

[Phys. Rev. Lett. 108, 030401] Published Wed Jan 18, 2012

In this Letter we use resolved sideband laser cooling to cool a mesoscopic mechanical resonator to near its quantum ground state (phonon occupancy 2.6±0.2), and observe the motional sidebands generated on a second probe laser. Asymmetry in the sideband amplitudes provides a direct measure of the dis...

[Phys. Rev. Lett. 108, 033602] Published Tue Jan 17, 2012