In rhombohedral ${\mathrm{CaMn}}_7{\mathrm{O}}_{12}$, an improper ferroelectric polarization of magnitude $2870\mu \mathrm{C}{\mathrm{m}}^{-2}$ is induced by an incommensurate helical magnetic structure that evolves below $T_{\mathrm{N}1}=90\mathrm{K}$. The electric polarization was found to be constrained to the high symmetry threefold rotation axis of the crystal structure, perpendicular to the in-plane rotation of the magnetic moments. The multiferroicity is explained by the ferroaxial coupling mechanism, which in ${\mathrm{CaMn}}_7{\mathrm{O}}_{12}$ gives rise to the largest magnetically induced, electric polarization measured to date.

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 efflorescence where no new efflorescence forms. These are explained from a visualization experiment, pore-network simulations and a simple efflorescence growth model.

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 $3.1\pm {0.6}_{\mathrm{stat}}\pm {0.3}_{\mathrm{syst}}\mathrm{counts}/(\mathrm{day}·100\mathrm{ton})$. Assuming the $pep$ neutrino flux predicted by the standard solar model, we obtained a constraint on the CNO solar neutrino interaction rate of $<7.9\mathrm{counts}/(\mathrm{day}·100\mathrm{ton})$ ($95\%$ C.L.). The absence of the solar neutrino signal is disfavored at $99.97\%$ C.L., while the absence of the $pep$ signal is disfavored at $98\%$ C.L. The necessary sensitivity was achieved by adopting data analysis techniques for the rejection of cosmogenic ${}^{11}\mathrm{C}$, the dominant background in the 1–2 MeV region. Assuming the Mikheyev-Smirnov-Wolfenstein large mixing angle solution to solar neutrino oscillations, these values correspond to solar neutrino fluxes of $(1.6\pm 0.3)\times {10}^8{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ and $<7.7\times {10}^8{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ ($95\%$ C.L.), respectively, in agreement with both the high and low metallicity standard solar models. These results represent the first direct evidence of the $pep$ neutrino signal and the strongest constraint of the CNO solar neutrino flux to date.

The Nernst coefficient for the quasi-one-dimensional metal, ${\mathrm{Li}}_{0.9}{\mathrm{Mo}}_6{\mathrm{O}}_{17}$, is found to be among the largest known for metals ($\nu \simeq 500\mu \mathrm{V}/\mathrm{KT}$ at $T\sim 20\mathrm{K}$), and is enhanced in a broad range of temperature by orders of magnitude over the value expected from Boltzmann theory for carrier diffusion. A comparatively small Seebeck coefficient implies that ${\mathrm{Li}}_{0.9}{\mathrm{Mo}}_6{\mathrm{O}}_{17}$ is bipolar with large, partial Seebeck coefficients of opposite sign. A very large thermomagnetic figure of merit, $ZT\sim 0.5$, is found at high field in the range $T\approx 35–50\mathrm{K}$.

The first direct mass measurement of ${}^6\mathrm{He}$ has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the mass of ${}^8\mathrm{He}$ was determined with improved precision over our previous measurement. The obtained masses are $m({}^6\mathrm{He})=6.018885883(57)\mathrm{u}$ and $m({}^8\mathrm{He})=8.03393444(11)\mathrm{u}$. The ${}^6\mathrm{He}$ value shows a deviation from the literature of $4\sigma$. With these new mass values and the previously measured atomic isotope shifts we obtain charge radii of 2.060(8) and 1.959(16) fm for ${}^6\mathrm{He}$ and ${}^8\mathrm{He}$, respectively. We present a detailed comparison to nuclear theory for ${}^6\mathrm{He}$, including new hyperspherical harmonics results. A correlation plot of the point-proton radius with the two-neutron separation energy demonstrates clearly the importance of three-nucleon forces.

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 represented by the pore density function that bears all the information on the collective pore microstructure. So far, conventional magnetic resonance imaging (MRI) could only detect the pore autocorrelation function, which inherently obscures fine details on the pore structure. Here, for the first time, we report on a unique imaging mechanism arising from synergistic diffusion-diffractions that directly yields the pore density function. This mechanism offers substantially higher spatial resolution compared to conventional MRI while retaining all fine details on the collective pore morphology. Thus, using these unique synergistic diffusion-diffractions, the “shape of the drum” can be inferred.

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 jumps. Both the experiment and its shallow water modeling demonstrate a robust linear instability and nonlinear properties of symmetry breaking, in a system which is one million times smaller and about one hundred times slower than its astrophysical analogue.

We show results on the vortex core dissipation through current-voltage measurements under applied pressure and magnetic field in the superconducting phase of ${\mathrm{CeCoIn}}_5$. We find that as soon as the system becomes superconducting, the vortex core resistivity increases sharply as the temperature and magnetic field decrease. The sharp increase in flux-flow resistivity is due to quasiparticle scattering on critical antiferromagnetic fluctuations. The strength of magnetic fluctuations below the superconducting transition suggests that magnetism is complementary to superconductivity and therefore must be considered in order to fully account for the low-temperature properties of ${\mathrm{CeCoIn}}_5$.

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 quantum states over a public quantum channel. If the eavesdropper intercepts the quantum communication she learns nothing about the message. In the classical case, a one-time pad can be created using shared and partially private correlations. Here we consider the quantum case in the presence of an eavesdropper, and find the single-letter formula for the rate at which the two parties can send messages using a general quantum state as a quantum one-time pad. Surprisingly, the formula coincides with the distillable entanglement assisted by a symmetric channel, an important quantity in quantum information theory, but which lacked a clear operational meaning.

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 comparable to the area of the lattice unit cell. Specifically, arrays of doped graphene nanodisks display full absorption when supported on a substrate under total internal reflection and also when lying on a dielectric layer coating a metal. Our results are relevant for infrared light detectors and sources, which can be made tunable via electrostatic doping of graphene.

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 ${\sigma }^2$. We show that the statistics of the gap $d_{k,n}=M_{k,n}-M_{k+1,n}$ between the $k$th and the $(k+1)$th maximum of the time series becomes stationary, i.e., independent of $n$ as $n\to \infty$ and exhibits a rich, universal behavior. The mean stationary gap exhibits a universal algebraic decay for large $k$, $⟨d_{k,\infty }⟩/\sigma \sim 1/\sqrt{2\pi k}$, independent of the details of the jump distribution. Moreover, the probability density (pdf) of the stationary gap exhibits scaling, $\mathrm{Pr}(d_{k,\infty }=\delta )\simeq (\sqrt{k}/\sigma )P(\delta \sqrt{k}/\sigma )$, in the regime $\delta \sim ⟨d_{k,\infty }⟩$. The scaling function $P(x)$ is universal and has an unexpected power law tail, $P(x)\sim x^{-4}$ for large $x$. For $\delta \gg ⟨d_{k,\infty }⟩$ the scaling breaks down and the pdf gets cut off in a nonuniversal way. Consequently, the moments of the gap exhibit an unusual multiscaling behavior.

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 at the sixth order of the expansion, albeit only in the $C$-odd–$P$-even sector, with coefficients that depend on quark masses, Cabibbo-Kobayashi-Maskawa matrix elements, temperature and the magnitude of the Higgs field. The $CP$ violating effects are observed to decrease rapidly with temperature, which has important implications for the generation of a matter-antimatter asymmetry in the early Universe. Our results suggest that the cold electroweak baryogenesis scenario may be viable within the standard model, provided the electroweak transition temperature is at most of order 1 GeV.

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 ${}^{24}\mathrm{Mg}$ and ${}^{32}\mathrm{Mg}$. A striking correspondence is found between the nuclear charge radius and the neutron shell structure. The importance of cluster configurations towards $N=8$ and collectivity near $N=20$ is discussed in the framework of the fermionic molecular dynamics model. These essential results have been made possible by the first application of laser-induced nuclear orientation for isotope shift measurements.

We demonstrate experimentally the production of Rydberg positronium (Ps) atoms in a two-step process, comprising incoherent laser excitation, first to the $2{}^{3}P$ state and then to states with principal quantum numbers ranging from 10 to 25. We find that excitation of $2{}^{3}P$ atoms to Rydberg levels occurs very efficiently ($\sim 90\%$) and that the $\sim 25\%$ overall efficiency of the production of Rydberg atoms is determined almost entirely by the spectral overlap of the primary excitation laser and the Doppler broadened width of the $1{}^{3}S\mathrm{\text{−}}2{}^{3}P$ transition. The observed efficiency of Rydberg Ps production can be explained if stimulated emission back to the $2P$ states is suppressed, for example, by intermixing of the Rydberg state Stark sublevels. The efficient production of long-lived Rydberg Ps in a high magnetic field may make it possible to perform direct measurements of the gravitational free fall of Ps.

We report on the observation of quantum interference of the emission from two separate nitrogen vacancy (NV) centers in diamond. Taking advantage of optically induced spin polarization in combination with polarization filtering, we isolate a single transition within the zero-phonon line of the nonresonantly excited NV centers. The time-resolved two-photon interference contrast of this filtered emission reaches 66%. Furthermore, we observe quantum interference from dissimilar NV centers tuned into resonance through the dc Stark effect. These results pave the way towards measurement-based entanglement between remote NV centers and the realization of quantum networks with solid-state spins.

We investigate the lifetime of two-electron spin states in a few-electron $\mathrm{Si}/\mathrm{SiGe}$ 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 the lifetimes of multiple states simultaneously. When the magnetic field is zero, we find that all three triplet states have equal lifetimes, as expected, and this time is $\sim 10\mathrm{ms}$. When the field is nonzero, the $T_0$ lifetime is unchanged, whereas the $T_{-}$ lifetime increases monotonically with the field, reaching 3 sec at 1 T.

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 $0,1,\dots ,n-1$ on a square lattice with a square boundary. The model is found to have several intriguing features, including a nonmonotonic dependence of the retention on the number of levels: for many $n$, the retention is counterintuitively greater than that of an ($n+1$)-level system. The behavior is explained using percolation theory, by mapping it to a 2-level system with variable probability. Results in one dimension are also found.

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 Higgs fields, and another where the strong dynamics is solely responsible for electroweak symmetry breaking. In both cases, the mass of the Higgs boson can exceed the LEP bound without tuning, solving the supersymmetry naturalness problem. A good precision electroweak fit can be obtained, and quark and lepton masses are generated without flavor-changing neutral currents. In addition to standard supersymmetry signals, these models predict production of multiple heavy standard model particles ($t$, $W$, $Z$, and $b$) from decays of resonances in the strong sector.

Evidence for the neutron-rich hypernucleus ${}_{\Lambda }{}^6\mathrm{H}$ is presented from the FINUDA experiment at $\mathrm{DA}\Phi \mathrm{NE}$, Frascati, studying $({\pi }^{+},{\pi }^{-})$ pairs in coincidence from the $K_{\mathrm{stop}}^{-}+{}^6\mathrm{Li}\to {}_{\Lambda }{}^6\mathrm{H}+{\pi }^{+}$ production reaction followed by ${}_{\Lambda }{}^6\mathrm{H}\to {}^6\mathrm{He}+{\pi }^{-}$ weak decay. The production rate of ${}_{\Lambda }{}^6\mathrm{H}$ undergoing this two-body ${\pi }^{-}$ decay is determined to be $(2.9\pm 2.0)\times {10}^{-6}/K_{\mathrm{stop}}^{-}$. Its binding energy, evaluated jointly from production and decay, is $B_{\Lambda }({}_{\Lambda }{}^6\mathrm{H})=(4.0\pm 1.1)\mathrm{MeV}$ with respect to ${}^5\mathrm{H}+\Lambda$. A systematic difference of $(0.98\pm 0.74)\mathrm{MeV}$ between $B_{\Lambda }$ values derived separately from decay and from production is tentatively assigned to the ${}_{\Lambda }{}^6\mathrm{H}$ $0_{\mathrm{g}.\mathrm{s}.}^{+}\to 1^{+}$ excitation.

The current emission noise of a carbon nanotube quantum dot in the Kondo regime is measured at frequencies $\nu$ of the order or higher than the frequency associated with the Kondo effect $k_B{T}_K/h$, with $T_K$ the Kondo temperature. The carbon nanotube is coupled via an on-chip resonant circuit to a quantum noise detector, a superconductor-insulator-superconductor junction. We find for $h\nu \approx k_B{T}_K$ a Kondo effect related singularity at a voltage bias $eV\approx h\nu$, and a strong reduction of this singularity for $h\nu \approx 3k_B{T}_K$, in good agreement with theory. Our experiment constitutes a new original tool for the investigation of the nonequilibrium dynamics of many-body phenomena in nanoscale devices.