micro- and nanomechanics; nuclear magnetic resonance; magnetic resonance imaging (MRI); mesoscopic physics; experimental condensed matter physics; magnetic resonance force microscopy; ultra-sensitive force microscopy
Herzog Benedikt, Cadeddu Davide, Xue Fei, Peddibhotla Phani, Poggio Martino (2014), Boundary between the thermal and statistical polarization regimes in a nuclear spin ensemble, in Applied Physics Letters
, 105(4), 043112.
Montinaro Michele, Wüst Gunter, Munsch Mathieu, Fontana Yannik, Russo-Averchi Eleonora, Heiss Martin, Fontcuberta i Morral Anna, Warburton Richard, Poggio Martino (2014), Quantum dot opto-mechanics in a fully self-assembled nanowire, in Nano Letters
, 14, 4454.
Peddibhotla Phani, Xue Fei, Hauge H.I.T., Assali Simone, Bakkers Erik, Poggio Martino (2013), Harnessing nuclear spin polarization fluctuations in a semiconductor nanowire, in Nature Physics
, 9, 631.
Nagel Joachim, Buchter Arne, Xue Fei, Kieler Oliver, Weimann T., Kohlmann J., Zorin A., Rüffer Daniel, Russo-Averchi Eleonora, Huber R., Berberich P., Fontcuberta i Morral Anna, Grundler Dirk, Kleiner Reinhold, Koelle Dieter, Poggio Martino, Kemmler Matthias (2013), Nanoscale multifunctional sensor formed by a Ni nanotube and a scanning Nb nanoSQUID, in Physical Review B
, 88, 064425.
Buchter Arne, Nagel Joachim, Rüffer Daniel, Xue Fei, Weber Dennis, Kieler Oliver, Weimann T., Kohlmann J., Zorin A., Russo-Averchi Eleonora, Huber R., Berberich P., Fontcuberta i Morral Anna, Kemmler M., Kleiner Reinhold, Koelle Dieter, Grundler Dirk, Poggio Martino (2013), Reversal mechanism of an individual Ni nanotube simultaneously studied by torque and SQUID magnetometry, in Physical Review Letters
, 111, 067202.
Weber Dennis, Rüffer Daniel, Buchter Arne, Xue Fei, Russo-Averchi Eleonora, Huber R., Berberich P., Arbiol J., Fontcuberta i Morral Anna, Grundler Dirk, Poggio Martino (2012), Cantilever magnetometry of individual Ni nanotubes, in Nano Letters
, 12, 6139.
Montinaro Michele, Mehlin Andrea, Solanki Hari, Peddibhotla Phani, Mack Shawn, Awschalom David, Poggio Martino (2012), Feedback cooling of cantilever motion using a quantum point contact transducer, in Applied Physics Letters
, 101, 133104.
The study and development of micro- and nanomechanical resonators has become a vibrant field of physics attracting intense interest among researchers and lay-people alike. Measurement techniques with unprecedented sensitivity, including torque magnetometry and force-detected magnetic resonance, have emerged as important applications of nanomechanical devices. High quality lithographically-defined nanomechanical oscillators are now being joined by a new class of self-assembled resonators such as nanowires and nanotubes. At the same time, we are perfecting our ability to study and control the quantum behavior of small mechanical structures. Researchers have recently developed techniques to initialize a mechanical oscillator in its ground state and even to prepare it in a variety of coherent states. This proposal consists of two projects in this vein: the coupling of mechanical modes to mesoscopic transport and nanoscale magnetic resonance force microscopy. The coupling of mechanical modes to mesoscopic transport (project A) represents an active and growing area of research whose pursuit has produced a series of interesting results. Various groups have observed nanomechanical effects in mesoscopic transport devices, most notably in suspended nanotube and nanowire (NW) transistors. Coupling of nanomechanical resonators to controllable quantum systems such as quantum dots (QDs) and superconducting qubits is in its early stages. These developments, combined with the recently demonstrated ability to initialize nanomechanical oscillators in their ground state, mean that researchers can begin to couple a quantum nanomechanical harmonic oscillator to a quantum two-level system. Such an experimental system is a veritable playground for experiments on quantum coherence and measurement theory. We intend to carry out several experiments in this direction including the continuation of attempts to couple quantum point contacts, QDs, and eventually an electronic Mach-Zehnder interferometer to a mechanical oscillator. We also plan to study nanomechanical couplings in suspended NW transistors. From a practical perspective, such systems provide an avenue for designing sensitive detectors of mechanical displacement | detectors which approach the quantum limit. Nanoscale magnetic resonance force microscopy (MRFM) (project B) and its application to semiconductor nanostructures combine the physics of magnetic resonance imaging (MRI) with the techniques of scanning probe microscopy. In the past few years, MRFM has made impressive strides forward in sensitivity and resolution. Nuclear MRI detected by MRFM has demonstrated a 3D spatial resolution better than 10 nm in organic samples. We have started and intend to continue applying this technique to semiconductor systems | in particular, semiconductor systems which contain too few nuclei to be measured by conventional means. Nanometer-scale structures such as QDs and NWs are interesting candidates, especially since the nuclear polarization dynamics within these structures are tightly coupled to the electron spin dynamics. In fact, the leading cause of decoherence for electron spin qubits in III-V QDs is the hyperne coupling to the lattice nuclear spins. Another particularly interesting prospect is the potential for sub-surface, isotopically selective imaging on the nanometer-scale in semiconductor materials. Conventional methods such as scanning electron microscopy and transmission electron microscopy notably lack such isotopic contrast. The main applicant, Prof. Martino Poggio, has been a tenure-track assistant professor in the Physics Department at the University of Basel since January 2009. He has built a state-of-the-art laboratory for research in nanomechanics, magnetic resonance, and mesoscopic transport. His group consists of 2 post-doctoral researchers, 4 Ph.D. students (2 supported by the SNF), and 3 Master students. He has collaborations around the world including with Prof. David Awschalom (UCSB), Prof. Connie Chang-Hasnain (UC Berkeley), Prof. Alex Holleitner (TU Munich), and Prof. Roberto Myers (Ohio State). Within Switzerland he is part of the NCCR Nanoscale and the NCCR Quantum Science and Technology and has active collaborations with Prof. Klaus Ensslin (ETH) and Prof. Anna Fontcuberta i Morral (EPFL). He collaborates with various colleagues in Basel, especially Prof. Richard Warburton.