Semiconductor Quantum Information Device Theory Research Team

Principal Investigator

PI Name

Daniel Loss

Degree

Ph.D.

Title

Team Leader

Brief Resume

1985	Ph.D. in Theoretical Physics, University of Zurich, Switzerland
1985	Postdoctoral Research Associate, University of Zurich, Switzerland
1989	Postdoctoral Research Fellow, University of Illinois at Urbana-Champaign, USA
1991	Research Scientist, IBM T. J. Watson Research Center, USA
1993	Assistant/Associate Professor, Simon Fraser University, Canada
1996	Professor, Department of Physics, University of Basel, Switzerland (-present)
2012	Team Leader, Emergent Quantum System Research Team, RIKEN
2013	Team Leader, Quantum System Theory Research Team, Quantum Information Electronics Division, RIKEN Center for Emergent Matter Science (-present)
2020	Team Leader, Semiconductor Quantum Information Device Theory Research Team, Quantum Computing Division, RIKEN Center for Emergent Matter Science (-present)

Outline

Our team is working on the theory of a spin-based quantum computer. We design its CMOS-compatible components deriving from Si and Ge gated quantum dots. We focus on spin qubits that can be manipulated by electric fields through various spin-orbit interactions. Using advanced bandstructure models, we investigate the properties of holes and electrons confined in low-dimensional geometries. We search for optimal setups and ways of protecting the qubits from noise. We analyze perspective qubit interconnects which would allow assembling a large number of qubits into networks. Our ultimate goal is to identify fast, small, and scalable elements of the future quantum computer.

Research Fields

Theoretical Physics, Quantum Theory of Condensed Matter

Keywords

Quantum dots
Spin-based quantum information science
Qubit
Spin-orbit interaction
Quantum information processing
Quantum information devices

Results

Measurement of a single-electron wave function

Lateral quantum dots, defined in a two-dimensional electron gas by nanometer-scale surface gates, show excellent flexibility. They allow to realize, in principle, arbitrary and tunable dot shapes, essential for spin-qubit control. The bottleneck in taking full advantage of this flexibility was that, so far, there has been no direct method available to adequately determine the quantum dot confinement geometry. We have developed a noninvasive technique that removes this obstacle. We developed theoretically and demonstrated experimentally methods to determine the wave function of a single electron located in a semiconductor. The method is based on in-plane magnetic-field-assisted spectroscopy which allows extraction of the in-plane orientation and full three-dimensional size parameters of the quantum mechanical orbitals of a single electron GaAs lateral quantum dot with subnanometer precision.

Sequence to measure the energies, the tunneling-in rate dependence, and the lowest states wave functions visualization.

Members

Daniel Loss	Team Leader	loss.daniel[at]riken.jp