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Quantum Coherence in Nanoscale Systems

English title Quantum Coherence in Nanoscale Systems
Applicant Zumbühl Dominik
Number 113776
Funding scheme Project funding (Div. I-III)
Research institution Departement Physik Universität Basel
Institution of higher education University of Basel - BS
Main discipline Condensed Matter Physics
Start/End 01.10.2006 - 30.09.2008
Approved amount 565'950.00
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Keywords (11)

quantum coherence; electron spin and GaAs nuclear spin; coherent manipulation of quantum states; quantum states; quantum computation; electron interactions; experimental condensed matter physics; nanoscience; mesoscopic physics; electron and GaAs nuclear spin physics;

Lay Summary (English)

Lay summary
This research grant consists of two projects:
1. electron spins in coupled quantum dots, working towards experimental implementation of quantum computation schemes.
2. fundamental mesoscopic transport phenomena probing electron interactions, coherence and spin in quantum dots.

Quantum coherence in nanoscale systems enables study of fundamental physics in condensed matter systems and has promising applications for quantum information processing. Experimental realization of proposed qubits in the solid state and investigation of the underlying physics controlling coherence is at the forefront of modern condensed matter physics. Realization of proposed quantum computers may potentially one day revolutionize our world, maybe in a similar way todays Silicon-transistor based computers did over the past decades.

The electron spin qubit project aims to better understand and control the spin and spin coherence of electrons in laterally defined GaAs coupled quantum dot nano structures. Currently, the GaAs nuclear spins are the main source of spin decoherence. We will investigate the electron-nucelar spin coupling and will attempt to find ways to control the nuclear induced electron spin dephasing. Also, experiments to coherently and in a controlled way rotate the electron spin will be performed, with methods including intrinsic spin-orbit coupling, quantum-dot g-tensor control or static magnetic field gradients. Efforts towards implementing several coupled qubits are also underway.

Quantum coherence, electron spins and electron interactions 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.

Experiments will investigate quantum transport through semiconductor nanostructures which will be fabricated in-house with both optical- and electron beam lithography nanofabrication techniques using GaAs high-mobility 2D electron gas materials, grown in molecular beam epitaxy labs. Experiments are typically performed in dilution refrigerators at millikelvin temperatures in magnetic fields. Measurements are done using electronic low-noise techniques and may involve nanosecond-pulsing and microsecond readout schemes.

We are affiliated with the NCCR Nanoscale Science center of the Swiss NSF (, the Basel Center for Quantum Computing and Quantum Coherence ( and the NSEC Harvard Nanoscale Science and Engineering Center ( of the US National Science Foundation.

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Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants


Associated projects

Number Title Start Funding scheme
121905 Quantum Coherence in Nanoscale Systems 01.10.2008 Project funding (Div. I-III)
121905 Quantum Coherence in Nanoscale Systems 01.10.2008 Project funding (Div. I-III)