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Control y detección de la mezcla singlet-triplete en un campo nuclear aleatorio
F H L Koppens1, J A Folk, J M Elzerman
1Kavli Institute of Nanoscience, Delft University of Technology, Post Office Box 5046, 2600 GA Delft, Netherlands.
Science (New York, N.Y.)
|July 23, 2005
Resumen
Las interacciones de espín nuclear en los puntos cuánticos causan mezcla de estados de electrones. La supresión de esta mezcla es clave para la manipulación de espín coherente, con un tiempo de coherencia de espín medido de 25 nanosegundos.
Área de la Ciencia:
- Ciencias de la información cuántica Ciencias de la información cuántica.
- Física de la materia condensada Física de la materia condensada
- La computación cuántica es la computación cuántica.
Sus antecedentes:
- Los puntos cuánticos son nanoestructuras de semiconductores que confinan los electrones.
- Los estados de espín de los electrones (singlet y triplet) son fundamentales para el procesamiento de información cuántica.
- Los espines nucleares en el semiconductor anfitrión pueden interactuar con los espines de los electrones.
Objetivo del estudio:
- Investigar el efecto de las interacciones de espín nuclear en los estados de espín de los electrones en un doble punto cuántico.
- Explorar métodos para suprimir la mezcla de estados de espín no deseados.
- Para determinar el impacto de estas interacciones en los tiempos de coherencia de espín.
Principales métodos:
- Utilizó un sistema de doble punto cuántico para estudiar los estados de dos electrones.
- Campos magnéticos aplicados y variado acoplamiento de túnel interdotal para controlar la división spin-singlet/triplet.
- Se analizaron las mediciones del transporte de electrones para observar la polarización del espín y las bistabilidades.
Principales resultados:
- Se observó una mezcla entre los estados singlet y triplet debido a las interacciones de espín nuclear.
- Se ha demostrado la supresión de esta mezcla a través de campos magnéticos y un mayor acoplamiento de túneles.
- Se extrajo un tiempo promedio de coherencia de espín (T2*) de 25 nanosegundos limitado por las fluctuaciones del campo nuclear.
Conclusiones:
- Las interacciones de espín nuclear afectan significativamente los estados de espín de los electrones en los puntos cuánticos.
- La manipulación coherente de los espines individuales de los electrones requiere el control de las interacciones electrón-núcleo.
- El tiempo de coherencia de espín medido pone de relieve un desafío clave para las tecnologías cuánticas.
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