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Coherent singlet-triplet oscillations in a silicon-based double quantum dot
B M Maune1, M G Borselli, B Huang
1HRL Laboratories LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA. bmmaune@hrl.com
Nature
|January 20, 2012
Summary
Researchers demonstrate coherent control of electron spins in silicon quantum dots, achieving a 360-nanosecond dephasing time. This breakthrough in silicon quantum computing significantly reduces nuclear spin interactions, paving the way for advanced quantum processors.
Area of Science:
- Quantum Information Science
- Condensed Matter Physics
- Materials Science
Background:
- Silicon is a leading material for microelectronics and shows promise for quantum information technologies.
- Controlling single electron spins in silicon devices is feasible using established fabrication methods.
- Weak interaction with nuclear spins in silicon offers an advantage over other materials for quantum bit stability.
Purpose of the Study:
- To achieve coherent control of electron spins in coupled quantum dots within a silicon-based heterostructure.
- To investigate and quantify the nuclei-induced dephasing time in such a system.
- To assess the potential of silicon for developing robust quantum information processors.
Main Methods:
- Fabrication of an undoped Si/SiGe heterostructure with two coupled quantum dots.
- Coherent control experiments on electron spins confined within these quantum dots.
- Measurement of nuclei-induced dephasing time using advanced experimental techniques.
Main Results:
- Demonstrated coherent control of electron spins in the silicon quantum dot system.
- Achieved a nuclei-induced dephasing time of 360 nanoseconds.
- Observed a nearly two-orders-of-magnitude improvement in dephasing time compared to GaAs-based quantum dots.
Conclusions:
- The developed silicon quantum dot system exhibits significantly enhanced phase coherence due to reduced nuclear spin interactions.
- Fast electrical initialization, read-out, and control capabilities are demonstrated.
- These findings strongly support the advancement of silicon-based quantum information processors.
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