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Transporte de largo alcance en estados oscuros excitónicos en pozos cuánticos acoplados

D Snoke¹, S Denev, Y Liu

¹Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pennsylvania 15260, USA. snoke@pitt.edu

|August 16, 2002

Resumen

Se observó que los excitones en los pozos cuánticos de InGaAs viajan cientos de micrómetros, mucho más allá de su límite de difusión típico. Este transporte de largo alcance se produce a través de un estado oscuro antes de volver colectivamente a estados luminiscentes.

Área de la Ciencia:

Física de la materia condensada Física de la materia condensada Física de la materia condensada Física de la materia condensada Física de la materia condensada
La óptica cuántica es una óptica cuántica.
Las heteroestructuras de semiconductores son heterostructuras de semiconductores.

Sus antecedentes:

Los pozos cuánticos acoplados se investigan para la condensación Bose-Einstein de los excitones.
El transporte de excitones en pozos cuánticos está típicamente limitado a unos pocos micrómetros debido a la corta vida útil y la dispersión.
El transporte coherente a larga distancia de excitones es un área clave de investigación.

Objetivo del estudio:

Para investigar el transporte de excitones en pozos cuánticos de InGaAs.
Observar y caracterizar el transporte de excitones de largo alcance más allá de los límites de difusión típicos.
Explorar los mecanismos potenciales, como la condensación de Bose, que subyace a este fenómeno.

Principales métodos:

Mediciones de fotoluminiscencia de los pozos cuánticos de arseniuro de gálio de indio (InGaAs).
La excitación láser para generar excitones.
Cartografía espacial de la fotoluminiscencia para observar la distribución de los excitones.

Principales resultados:

Observación de la luminiscencia del excitón que aparece a cientos de micrómetros del punto de excitación del láser.
La luminiscencia forma un anillo alrededor del punto de excitación, con una emisión mínima en el medio.
Los excitones parecen viajar en un estado no luminiscente (oscuro) antes de convertirse colectivamente en luminiscentes a una distancia crítica.

Conclusiones:

Se ha observado un nuevo mecanismo de transporte de largo alcance para excitones en pozos cuánticos.
El fenómeno observado sugiere que los excitones pueden viajar en un estado oscuro a distancias significativas.
La relación de este efecto con la condensación de Bose-Einstein y la coherencia macroscópica requiere más investigación.

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