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Manipulación coherente de espines de electrones acoplados en puntos cuánticos de semiconductores
J R Petta1, A C Johnson, J M Taylor
1Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Science (New York, N.Y.)
|September 6, 2005
Resumen
Logramos un control preciso sobre los estados de espín de dos electrones en un punto cuántico doble utilizando pulsos eléctricos. Este control cuántico extendió significativamente el tiempo de coherencia más allá de 1 microsegundo, superando las interacciones hiperfinas.
Área de la Ciencia:
- La computación cuántica es la computación cuántica.
- Ciencias de la información cuántica Ciencias de la información cuántica.
- Física del estado sólido Física del estado sólido
Sus antecedentes:
- Los sistemas cuánticos requieren un control preciso para la computación.
- Los estados de espín de dos electrones en puntos cuánticos son qubits prometedores.
- Las interacciones hiperfinas limitan la coherencia del estado cuántico.
Objetivo del estudio:
- Para demostrar el control coherente de los estados de espín de dos electrones.
- Para medir y extender el tiempo de coherencia de estos estados de espín.
- Para investigar el impacto de las interacciones hiperfinas en la coherencia cuántica.
Principales métodos:
- Utilizó un rápido control eléctrico de la interacción de intercambio en un doble punto cuántico.
- Se emplea la separación y la recombinación del estado de giro individual para la medición del tiempo de desfase.
- Aplicó oscilaciones de Rabi y secuencias de pulsos de eco de espín para la manipulación cuántica y la mejora de la coherencia.
Principales resultados:
- Logró la preparación del estado, la manipulación coherente y la lectura proyectiva de los estados de espín de dos electrones.
- Se midió un tiempo de desfase de giro (T2 *) de aproximadamente 10 nanosegundos, limitado por interacciones hiperfinas.
- Se demostraron las oscilaciones de Rabi y la supresión de la desfase utilizando secuencias de giro-eco.
- Extendió el tiempo de coherencia de los estados de espín de dos electrones a más de 1 microsegundo.
Conclusiones:
- Las técnicas de control coherente permiten una manipulación precisa de los estados de espín de dos electrones.
- Las interacciones hiperfinas son una limitación primaria de la coherencia en GaAs, pero pueden mitigarse.
- Se lograron largos tiempos de coherencia superiores a 1 microsegundo, allanando el camino para el procesamiento avanzado de información cuántica.
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