Single electron-phonon interaction in a suspended quantum dot phonon cavity

An electron-phonon cavity consisting of a quantum dot embedded in a free-standing GaAs/AlGaAs membrane is characterized in Coulomb blockade measurements at low temperatures. We find a complete suppression of single electron tunneling around zero bias leading to the formation of an energy gap in the transport spectrum. The observed effect is induced by the excitation of a localized phonon mode confined in the cavity. This phonon blockade of transport is lifted at magnetic fields where higher electronic states with nonzero angular momentum are brought into resonance with the phonon energy.Comment: 4 pages, 4 figure

The effect of Landau-Zener dynamics on phonon lasing

Optomechanical systems couple light to the motion of nanomechanical objects. Intriguing new effects are observed in recent experiments that involve the dynamics of more than one optical mode. There, mechanical motion can stimulate strongly driven multi-mode photon dynamics that acts back on the mechanics via radiation forces. We show that even for two optical modes Landau-Zener-Stueckelberg oscillations of the light field drastically change the nonlinear attractor diagram of the resulting phonon lasing oscillations. Our findings illustrate the generic effects of Landau-Zener physics on back-action induced self-oscillations.Comment: 6 pages, 4 figure

Electrical characterization of electrochemically grown single copper nanowires

Single- and poly-crystalline copper wires with diameters down to 30 nm are grown in etched ion-track membranes. Individual nanowires are isolated and contacted by means of optical lithography. Electronic transport properties and oxidation processes are investigated. Depending on the oxidation state, the wire resistance varies between a few hundred ohms and several megaohms, enabling its usage as metallic or semiconducting structural elements for devices on the nanometer scale

Integrating suspended quantum dot circuits for applications in nanomechanics

We present an integrated nanoelectromechanical circuit designed for achieving ultrasensitive displacement detection. It consists of a suspended quantum dot defined in the two-dimensional electron system of an AlGaAs/GaAs heterostructure and a mechanical resonator located in close vicinity. Operation of the individual components is demonstrated: Mechanical as well as transport properties of the resonator and the electron system are specified, respectively. Coulomb blockade in a freely suspended quantum dot is revealed. The data are used to estimate the maximum displacement sensitivity of the device to be 0.029 Å/sqrt(Hz)

Magnetotransport in freely suspended two-dimensional electron systems for integrated nanomechanical resonators

We present magnetotransport measurements on freely suspended two-dimensional electron gases. Samples are prepared from GaAs/AlGaAs-heterostructures containing an additional sacrificial layer. The electronic properties of the system are characterized in standard magnetotransport measurements whereas the mechanical degrees of freedom are investigated in radio frequency resonance experiments. The interplay of both can be exploited for ultrasensitive displacement detection