Ion beam lithography for Fresnel zone plates in X-ray microscopy

Fresnel Zone Plates (FZP) are to date very successful focusing optics for X-rays. Established methods of fabrication are rather complex and based on electron beam lithography (EBL). Here, we show that ion beam lithography (IBL) may advantageously simplify their preparation. A FZP operable from the extreme UV to the limit of the hard X-ray was prepared and tested from 450 eV to 1500 eV. The trapezoidal profile of the FZP favorably activates its 2nd order focus. The FZP with an outermost zone width of 100 nm allows the visualization of features down to 61, 31 and 21 nm in the 1st, 2nd and 3rd order focus respectively. Measured efficiencies in the 1st and 2nd order of diffraction reach the theoretical predictions

On-chip phonon-magnon reservoir for neuromorphic computing

Reservoir computing is a concept involving mapping signals onto a high-dimensional phase space of a dynamical system called "reservoir" for subsequent recognition by an artificial neural network. We implement this concept in a nanodevice consisting of a sandwich of a semiconductor phonon waveguide and a patterned ferromagnetic layer. A pulsed write-laser encodes input signals into propagating phonon wavepackets, interacting with ferro-magnetic magnons. The second laser reads the output signal reflecting a phase-sensitive mix of phonon and magnon modes, whose content is highly sensitive to the write-and read-laser positions. The reservoir efficiently separates the visual shapes drawn by the write-laser beam on the nanodevice surface in an area with a size comparable to a single pixel of a modern digital camera. Our finding suggests the phonon-magnon interaction as a promising hardware basis for realizing on-chip reservoir computing in future neuro-morphic architectures

Coherent Phononics of van der Waals Layers on Nanogratings

Strain engineering can be used to control the physical properties of two-dimensional van der Waals (2D-vdW) crystals. Coherent phonons, which carry dynamical strain, could push strain engineering to control classical and quantum phenomena in the unexplored picosecond temporal and nanometer spatial regimes. This intriguing approach requires the use of coherent GHz and sub-THz 2D phonons. Here, we report on nanostructures that combine nanometer thick vdW layers and nanogratings. Using an ultrafast pump-probe technique, we generate and detect in-plane coherent phonons with frequency up to 40 GHz and hybrid flexural phonons with frequency up to 10 GHz. The latter arises from the periodic modulation of the elastic coupling of the vdW layer at the grooves and ridges of the nanograting. This creates a new type of a tailorable 2D periodic phononic nanoobject, a flexural phononic crystal, offering exciting prospects for the ultrafast manipulation of states in 2D materials in emerging quantum technologies

Protected Long-Distance Guiding of Hypersound Underneath a Nanocorrugated Surface

In nanoscale communications, high-frequency surface acoustic waves are becoming effective data carriers and encoders. On-chip communications require acoustic wave propagation along nanocorrugated surfaces which strongly scatter traditional Rayleigh waves. Here, we propose the delivery of information using subsurface acoustic waves with hypersound frequencies of ∼20 GHz, which is a nanoscale analogue of subsurface sound waves in the ocean. A bunch of subsurface hypersound modes are generated by pulsed optical excitation in a multilayer semiconductor structure with a metallic nanograting on top. The guided hypersound modes propagate coherently beneath the nanograting, retaining the surface imprinted information, at a distance of more than 50 μm which essentially exceeds the propagation length of Rayleigh waves. The concept is suitable for interfacing single photon emitters, such as buried quantum dots, carrying coherent spin excitations in magnonic devices and encoding the signals for optical communications at the nanoscale

Methoden zur Optimierung einer EZR-Ionenquelle auf die Produktion hochgeladener Ionen

Die vorliegende Arbeit befasst sich mit den gängigen Optimierungsmethoden von Elektron-Zyklotron-Resonanz-(EZR-)Ionenquellen und deren plasmaphysikalischen Grundlagen. Besonderes Augenmerk wurde bei den experimentellen Untersuchungen auf den Gasmischungseffekt, die vorgespannte Endplatte und den Aftergloweffekt gelegt. Mit Hilfe dieser Effekte kann der Ausstoß hochgeladener Ionen aus der Quelle signifikant gesteigert werden. Die von den Anwendern angeführten Erklärungsmodelle der obigen Effekte, wie z. B. die Ionenkühlung, weisen vom plasmaphysikalischen Standpunkt erhebliche Mängel auf und werden daher in dieser Arbeit eigenen Erklärungsansätzen wie Plasmawandwechselwirkungen und der Simondiffusion gegenübergestellt. Die Auswirkungen niederfrequenter Plasmawellen, die durch parametrischen Zerfall der eingespeisten Mikrowelle entstehen, auf die Formierung der Ladungszustandsverteilung werden am Beispiel der sog. Isotopenanomalie untersucht

SSB Binding to Single-Stranded DNA Probed Using Solid-State Nanopore Sensors

Single-stranded DNA (ssDNA) binding protein plays an important role in the DNA replication process in a wide range of organisms. It binds to ssDNA to prevent premature reannealing and to protect it from degradation. Current understanding of SSB/ssDNA interaction points to a complex mechanism, including SSB motion along the DNA strand. We report on the first characterization of this interaction at the single-molecule level using solid-state nanopore sensors, namely without any labeling or surface immobilization. Our results show that the presence of SSB on the ssDNA can control the speed of nanopore translocation, presumably due to strong interactions between SSB and the nanopore surface. This enables nanopore-based detection of ssDNA fragments as short as 37 nt, which is normally very difficult with solid-state nanopore sensors, due to constraints in noise and bandwidth. Notably, this fragment is considerably shorter than the 65 nt binding motif, typically required for SSB binding at high salt concentrations. The nonspecificity of SSB binding to ssDNA further suggests that this approach could be used for fragment sizing of short ssDNA

Hybrid coherent control of magnons in a ferromagnetic phononic resonator excited by laser pulses

We propose and demonstrate the concept of hybrid coherent control (CC) whereby a quantum or classical harmonic oscillator is excited by two excitations: one is quasi-harmonic (i.e. harmonic with a finite lifetime) and the other is a pulsed broadband excitation. Depending on the phase relation between the two excitations, controlled by the detuning of the oscillator eigenfrequencies and the waveforms of the quasi-harmonic and broadband excitations, it is possible to observe Fano-like spectra of the harmonic oscillator due to the interference of the two responses to the simultaneously acting excitations. Experimentally, as an example, the hybrid CC is implemented for magnons in a ferromagnetic grating where GHz coherent phonons act as the quasi-harmonic excitation and the broadband impact arises from pulsed optical excitation followed by spin dynamics in the ferromag-netic nanostructure. Coherent control (CC) is well established as a powerful method to manipulate the amplitude and phase of quantum states. First used for chemical reactions [1, 2], CC has been demonstrated for single electrons [3], spins [4, 5], nanoelectromechanical oscillators [6], magnons [7, 8] and other systems [9]. The basic phenomenon governing CC is the interference of the responses of a quantum system to specific excitations, which determine the phase of the wavefunction. One of the common technical solutions for realizing CC is to use two optical pulses from ultrafast lasers with adjustable time separation or more sophisticated laser pulse shaping [10]. For CC of magnons, two microwave pulses may be used [11]. Traditionally , the excitations that lead to the interfering responses have the same origin, e.g. transitions between the ground and an excited quantum state are induced by a resonant electromagnetic field. However, there are quantum systems that may be excited by a pair of exci-tations of different origins. For example, one excitation may be broad-band and the other harmonic. Exploiting a combination of various types of excitations for hybrid CC would broaden a diversity of CC applications for quantum computing and communications. The idea of hybrid CC in the spectral domain is illustrated in Figs. 1(a) and 1(b) for a linear tunable quantum or classical oscillator with eigenfrequency ω 0 and finite lifetime. Figures 1(a) and 1(b) show the amplitude spectra of the oscillator's responses to two types of excitation: (1) quasi-harmonic (i.e. harmonic with finite lifetime) excitation with central frequency ω R detuned relative to ω 0 ; and (2) broad band excitation. Two cases of detun-ing are considered: negative (ω 0 ω R) in Fig. 1(b). The top blue curves show the spectra when only quasi-harmonic excitation is present. In this case the phase ϕ of the oscillator at ω = ω 0 changes by π when the oscillator eigenfrequency is tuned through the resonance ω = ω R , say from −π/2 to π/2 as demonstrated in the comparison of the blue spectra in Figs. 1(a) and 1(b). The middle red curves are spectral responses when the oscillator is excited by a broadband excitation (2). The oscillator's phase ϕ, e.g. ϕ = π/2, at ω = ω 0 in this case does not depend on ω 0. The lower black curves are the spectra when the two ex-citations, (1) and (2), operate together. Clearly, we get destructive [ Fig. 1(a)] or constructive [Fig. 1(b)] interference of the oscillator's responses at ω = ω 0 depending on the detuning of the oscillator eigenfrequency relative to the central frequency of the quasi-harmonic excitation, ω 0 ω R respectively. For negative detuning (ω 0 ω R) the spectral amplitude at ω = ω 0 increases by a factor of two. The interference effects represent an example of hybrid CC where two excitations have different spectra and are of different nature, for example (1) could be a coherent phonon wavepacket and (2) could be a short microwave or laser pulse. By varying the detuning, amplitudes and phases of excitations (1) and (2), it is possible to model various Fano-like spectral shapes similar to Fano spectra which appear as a result of interference of broad-and narrow-band eigenstates [12]. In the present Letter we demonstrate an example where CC is realized for the case of magnons. Magnons are a typical example for which a diversity of quantum excitations exists [13]. The quasi-harmonic excitation of magnons is coming from quasi-monochromatic surface phonons. They drive the spectrally isolated magnon mode at the frequency ω R. The broadband excitation is based on ultrafast modulation of the ferromagnet mag-netization. Both excitations are triggered optically by a femtosecond laser pulse. The magnon eigenfrequency ω 0 is tuned by the external magnetic field B. Monitoring the magnon spectrum, we observe destructive or constru

Single-Molecule Studies of Intrinsically Disordered Proteins Using Solid-State Nanopores

Partially or fully disordered proteins are instrumental for signal-transduction pathways; however, many mechanistic aspects of these proteins are not well-understood. For example, the number and nature of intermediate states along the binding pathway is still a topic of intense debate. To shed light on the conformational heterogeneity of disordered protein domains and their complexes, we performed single-molecule experiments by translocating disordered proteins through a nanopore embedded within a thin dielectric membrane. This platform allows for single-molecule statistics to be generated without the need of fluorescent labels or other modification groups. These studies were performed on two different intrinsically disordered protein domains, a binding domain from activator of thyroid hormone and retinoid receptors (ACTR) and the nuclear coactivator binding domain of CREB-binding protein (NCBD), along with their bimolecular complex. Our results demonstrate that both ACTR and NCBD populate distinct conformations upon translocation through the nanopore. The folded complex of the two disordered domains, on the other hand, translocated as one conformation. Somewhat surprisingly, we found that NCBD undergoes a charge reversal under high salt concentrations. This was verified by both translocation statistics as well as by measuring the ζ-potential. Electrostatic interactions have been previously suggested to play a key role in the association of intrinsically disordered proteins, and the observed behavior adds further complexity to their binding reactions

Supplementary information files for On-chip phonon-magnon reservoir for neuromorphic computing

© the authors, CC-BY 4.0Supplementary files for article On-chip phonon-magnon reservoir for neuromorphic computingReservoir computing is a concept involving mapping signals onto a high-dimensional phase space of a dynamical system called “reservoir” for subsequent recognition by an artificial neural network. We implement this concept in a nanodevice consisting of a sandwich of a semiconductor phonon waveguide and a patterned ferromagnetic layer. A pulsed write-laser encodes input signals into propagating phonon wavepackets, interacting with ferromagnetic magnons. The second laser reads the output signal reflecting a phase-sensitive mix of phonon and magnon modes, whose content is highly sensitive to the write- and read-laser positions. The reservoir efficiently separates the visual shapes drawn by the write-laser beam on the nanodevice surface in an area with a size comparable to a single pixel of a modern digital camera. Our finding suggests the phonon-magnon interaction as a promising hardware basis for realizing on-chip reservoir computing in future neuromorphic architectures.</p