quantum coherence; electron spin and GaAs nuclear spin; coherent manipulation of quantum states; quantum computation; electron interactions; experimental condensed matter physics; nanoscience; mesoscopic physics; electron and GaAs nuclear spin physics;
Casparis L., Maschke M., Maradan D., Clark A. C., Scheller C., Schwarzwaelder K. K., Pekola J. P., Zumbuhl D. M., Metallic Coulomb Blockade Thermometry down to 10 mK and below, in cond-mat
, 1111(1972), 1-3.
Clark A. C., Schwarzwaelder K. K., Bandi T., Maradan D., Zumbuhl D. M., Method for cooling nanostructures to microkelvin temperatures, in Review of Scientific Instruments
, 81, 103904-1-103904-4.
Amasha S., MacLean K., Radu I. P., Zumbuhl D. M., Kastner M. A., Spin-Dependent Tunneling of Single Electrons into an Empty Quantum Dot, in Physical Review B
, 78, 041306R-1-041306R-4.
Koelbl D., Zumbuhl D. M., Fuhrer A., Salis G., Alvarado S., The Nuclear Spin Environment in Lateral GaAs Spin Valves, in cond-mat
, 1109(6332), 1-7.
Macroscopic control of coherent quantum states is a major theme in much of modern physics because quantum coherence enables study of fundamental physics and has promising applications for quantum information processing. The potential significance of quantum computing is by now widely recognized. This proposal consists of three projects: electron spin qubits in coupled quantum dots, topologically protected coherence in non-Abelian fractional quantum hall states and fundamental mesoscopic transport phenomena probing electron interactions, coherence and spin in quantum dots.The electron spin qubit in coupled quantum dots (project A) is currently among most promising quantum computing schemes. Despite impressive recent experimental progress in spin manipulation, spin coherence is currently significantly impeded by nuclear host-spin fluctuations. The experiments proposed here aim to tackle this coherence challenge. We intend to investigate the nuclear hyperfine physics and dynamics using spin Blockade and creating nuclear polarizations and aim to strongly enhance spin coherence with nuclear spin state narrowing techniques including spin resonance methods. As spin relaxation always fundamentally limits coherence, we intend to further study the low field and field anisotropy properties of spin relaxation.The prospect of physically realizing non-Abelian quantum states (project B) with topological properties is very exciting because no such quantum states have yet been discovered in nature, though the physics to be discovered would be truly unique and novel. Potential applications for topologically protected quantum computation further motivate experiments aimed at demonstrating non-Abelian statistics, which we propose to perform using quantum interference effects in certain even denominator fractional quantum Hall states.Quantum coherence, electron spin and electron interactions (project C) were and remain very much at the center of mesoscopic physics. We propose to tackle new aspects of these recurring themes by investigating a two impurity Kondo effect and a related quantum phase transition in a two electron double quantum dot. Electron interactions and coherence also are manifest in the many-body physics of mesoscopic Fermi edge resonances and magnetic field asymmetries of finite bias conductance through open quantum dots. The naturally unifying theme in this proposal is quantum coherence, which is central to mesoscopic physics in general as much as to quantum computation in particular.The main applicant is Prof. Dominik Zumbühl, an assistant professor who for the past 18 months has been initiating the Quantum Coherence Group and measurement lab at the Department of Physics, University of Basel. The lab setup has made excellent progress, and currently first experiments on Basel-fabricated few electron double dots with charge sensors are under way in a newly installed cryostat. Prof. Zumbühl has a strong background in mesoscopic and quantum dot physics and was educated in some of the worlds leading labs at Stanford, Harvard and MIT. Recently, Prof. Zumbühl was awarded one of the highly contested Starting Grants from the European Research Council (ERC). Together with our international collaborations with groups at Harvard, Alcatel-Lucent Bell-Labs, MIT and UCSB as well as Swiss and also in-house collaborations, we form an outstanding and internationally recognized team working together on these projects.We are affiliated with the NCCR Nanoscale Science center of the Swiss NSF (www.nccr-nano.org), the Basel Center for Quantum Computing and Quantum Coherence (www.qc2.unibas.ch) and the NSEC Harvard Nanoscale Science and Engineering Center (www.nsec.harvard.edu) of the US National Science Foundation.For more information, visit http://ZumbuhlLab.unibas.ch