Resistively detected nuclear magnetic resonance is used to measure the Knight shift of the 75 As nuclei and determine the electron spin polarization of the fractional quantum Hall states of the second Landau level. We show that the 5/2 state is fully polarized within experimental error, thus confirming a fundamental assumption of the Moore-Read theory. We measure the electron heating under radio frequency excitation, and show that we are able to detect NMR at electron temperatures down to 30 mK.PACS numbers: 73.43.FjThe physics of interacting electrons at half integer filling factor has intrigued researchers over the past two decades. It was found that the behavior at the first Landau level can be understood in terms of non-interacting composite fermions (CF) at zero magnetic field [1]. Numerous experimental findings confirm this picture, and establish the formation of a non-gaped state at ν = 1/2. The behavior in the second Landau level is, however, fundamentally different. Early experiments, dating back to the late eighties, show the formation of a fractional quantum Hall (FQH) state at ν = 5/2 [2,3]. This observation has challenged the CF theory and triggered an intense theoretical effort. Early on Moore and Read (MR) have suggested that a weak residual attractive interaction in the second Landau level gives rise to pairing of the CFs, and to the formation of a gaped state [4]. One of the exciting aspects of MR theory is the predicted excitation spectrum of the ν = 5/2 state, which should consist of quasiparticles that obey non-Abelian braiding statistics. It was shown that this property may turn the 5/2 state into a platform for quantum computing by means of topological manipulations [5].The examination of MR theory has become the focus of intensive experimental effort in recent years. A major support for its validity has been provided by the measurement of the quasiparticle charge, found to be e/4, in agreement with the prediction of the MR theory [6,7]. However, this finding is also consistent with other competing theories [1], and further experimental support is needed. The determination of the electron spin polarization can provide this needed support. A central assumption of the MR theory is that the electrons in the second Landau level are fully-polarized, and can therefore form pairs with p-type symmetry. Hence, confirming this point would provide a strong experimental evidence for the validity of the MR theory. Unfortunately, the experiments realized so far to probe the polarization at ν = 5/2 have led to ambiguous results: Tilted field experiments have shown that the ν = 5/2 gap decreases with tilt angle [8,9], which could be interpreted in favor of a spin depolarized ground state. However, this behavior may also originate from the destruction of the 5/2 state induced by the orbital coupling to the parallel magnetic field [10][11][12]. Optical measurements also provided indications, which supported an unpolarized ground state. Raman experiments have shown diminishing of the spin flip mode, and were ...

We present an electrically driven plasmonic device consisting of a gold nanoparticle trapped in a gap between two electrodes. The tunneling current in the device generates plasmons, which decay radiatively. The emitted spectrum extends up to an energy that depends on the applied voltage. Characterization of the electrical conductance at low temperatures allows us to extract the voltage drop on each tunnel barrier and the corresponding emitted spectrum. In several devices we find a pronounced sharp asymmetrical dip in the spectrum, which we identify as a Fano resonance. Finite-difference time-domain (FDTD) calculations reveal that this resonance is due to interference between the nanoparticle and electrodes dipolar fields, and can be conveniently controlled by the structural parameters. Electrically driven plasmonic devices may offer unique opportunities as a research tool and for practical applications [1][2][3][4][5] . In such devices, current that flows across a metallic tunnel junction

We study the transition from fluid at rest to turbulence in a rotating tank. The energy is transported by inertial wave packets through the fluid volume. These high amplitude waves propagate at velocities consistent with those calculated from linearized theory [H. P. Greenspan, (Cambridge University Press, Cambridge, England, 1968)]. A "front" in the temporal evolution of the energy power spectrum indicates a time scale for energy transport at the linear wave speed. Nonlinear energy transfer between modes is governed by a different, longer, time scale. The observed mechanisms can lead to significant differences between rotating and two-dimensional turbulent flows.

We experimentally study the characteristics of an inverse energy cascade in deep rotating turbulence. Experiments were performed in a rotating cylindrical water tank with energy injection at a small scale. The steady state energy spectrum of the horizontal velocity field at scales larger than the injection scale is very well described by the 2D inverse energy cascade spectrum. Transient energy spectra evolve via 2D-like inverse cascade, with energy transfer from small to large scales. The measured energy transfer rates are in good quantitative agreement with the predictions for 2D turbulence.

In this work, we investigate the dynamics of a single electron surface trap, embedded in a self-assembly metallic double-dot system. The charging and discharging of the trap by a single electron is manifested as a random telegraph signal of the current through the double-dot device. We find that we can control the duration time that an electron resides in the trap through the current that flows in the device, between fractions of a second to more than an hour. We suggest that the observed switching is the electrical manifestation of the optical blinking phenomenon, commonly observed in semiconductor quantum dots.