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Electron Spin Resonance based Quantum Computing

Objective

The application of electron spin resonance (ESR) and related techniques to the development of semiconductor-based quantum computing devices is a promising and challenging objective. However, for the realisation of quantum logic gates based on ESR further detailed knowledge is needed both on the materials science of the paramagnetic states in semiconductors which could be used for the construction of quantum logic gates as well as on the feasibility of the integration of such devices with conventional microelectronics which requires the development of novel and very sensitive ESR detection techniques based on electronic transport. These issues will be addressed systematically to identify the most promising ESRQC scheme with potential for large-scale integration to be pursued after the assessment. The application of electron spin resonance (ESR) and related techniques to the development of semiconductor-based quantum computing devices is a promising and challenging objective. However, for the realisation of quantum logic gates based on ESR further detailed knowledge is needed both on the materials science of the paramagnetic states in semiconductors which could be used for the construction of quantum logic gates as well as on the feasibility of the integration of such devices with conventional microelectronics which requires the development of novel and very sensitive ESR detection techniques based on electronic transport. These issues will be addressed systematically to identify the most promising ESRQC scheme with potential for large-scale integration to be pursued after the assessment.

OBJECTIVES
While a full project would aim at the actual realization of a basic solid-state ESRQC gate, it is the objective of the assessment project to explore key elements which are prerequisites for the successful demonstration of a working ESRQC device.
These key elements are:
-the identification of a suitable semiconductor matrix and the paramagnetic states (such as dopants, point defects or complexes) which are expected to be the best candidates for the use in quantum logic gates;
- the demonstration that the magnetic resonance of single paramagnetic states can be detected with electronic transport measurements.

DESCRIPTION OF WORK
Phosphorous or other donor atoms are typically proposed as the paramagnetic state in a quantum logic gates in ESRQC devices based on Si/SiGe hetero-structures. While the paramagnetic properties (hyperfine coupling of the electron to the P nucleus and the relaxation times) are well know for the various donors in crystalline Si, in SiGe alloys the hyperfine coupling is only known for phosphorous atoms in alloys with low Ge concentration and no information on the relaxation times is known at all. To be able to judge the viability of these concepts based on donor atoms in Si and SiGe alloys, we will determine the hyperfine coupling as well as the relaxation time of selected single and double donors in Si and over an extended alloy range in thick epitaxial layers grown by chemical vapour deposition. Using conventional ESR, the hyperfine coupling constants will be determined. Time resolved ESR techniques will be used as a very efficient way to determine the relaxation time of the defects. Spin resonance of single paramagnetic states has been successfully detected using optically detected magnetic resonance (ODMR).
Until now, the highest sensitivity for the detection of spins via resonant changes of electronic transport through a semiconductor device is 100 spins. In principle, single spin states should be identified with electrical means in an ESRQC. For this proof-of-principle experiment, we will use metal-oxide-semiconductor field-effect transistors (MOSFET) with small gate areas, in which random switching of the source-drain current is observed (random telegraph noise, RTN). Such MOSFETs exhibiting RTN are the semiconductor devices with single defects, which are most similar to the devices currently proposed for ESRQC gates. Resonant changes of the noise power density will be determined using a combination of conventional noise measurement techniques and ESR or via resonant changes of the characteristic capture and emission times, which can be obtained by a statistic al analysis.

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Coordinator

ISTITUTO NAZIONALE PER LA FISICA DELLA MATERIA

Address

Corso F. Perrone 24
16152 Genova

Italy

Participants (1)

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TECHNISCHE UNIVERSITAET MUENCHEN

Germany

Project information

Grant agreement ID: IST-2001-33573

  • Start date

    1 April 2002

  • End date

    31 March 2003

Funded under:

FP5-IST

  • Overall budget:

    € 100 000

  • EU contribution

    € 100 000

Coordinated by:

ISTITUTO NAZIONALE PER LA FISICA DELLA MATERIA

Italy