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Microscopia con resolución de espín y densidad de correlaciones antiferromagnéticas en cadenas de Fermi-Hubbard

Martin Boll¹, Timon A Hilker¹, Guillaume Salomon¹

¹Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.

Science (New York, N.Y.)

|September 17, 2016

Resumen

Los científicos observaron correlaciones de espín antiferromagnético de largo alcance en fermiones ultrafríos simulando el modelo de Hubbard. Este avance en la microscopía cuántica de gases allana el camino para el estudio de la superconductividad a alta temperatura.

Área de la Ciencia:

Física de la materia condensada
Simulación Cuántica
Gases atómicos ultrafríos

Sus antecedentes:

El repulsivo hamiltoniano de Hubbard es fundamental para entender los electrones fuertemente correlacionados y la superconductividad a alta temperatura.
Los fermiones ultrafríos en redes ópticas ofrecen una plataforma controlable para simular el hamiltoniano de Hubbard, lo que permite estudios de energía cinética, interacciones y dopaje.
La observación de correlaciones de espín antiferromagnético de largo alcance es crucial pero desafiante debido a los requisitos de entropía.

Objetivo del estudio:

Para detectar y caracterizar directamente las correlaciones de espín antiferromagnético más allá de los vecinos más cercanos en las cadenas de Hubbard de espín 1/2.
Lograr y utilizar entropias por partícula muy por debajo de s* = ln(2) para observar estas correlaciones.
Para permitir el estudio de la interacción entre el ordenamiento magnético y el dopaje.

Principales métodos:

Utilizando microscopios cuánticos de gas para la detección de un solo sitio.
Simulando el spin-1/2 del hamiltoniano de Hubbard con fermiones ultrafríos en las redes ópticas.
Lograr estados de baja entropía (s* < ln(2) en el sistema fermiónico.

Principales resultados:

Detección directa de correlaciones antiferromagnéticas en un solo sitio que se extiende hasta tres sitios en cadenas de Hubbard de espín 1/2.
Operación exitosa con entropias por partícula muy por debajo de s* = ln(2).
Se logró la detección simultánea de la información de giro y densidad.

Conclusiones:

El estudio demuestra la capacidad de observar correlaciones antiferromagnéticas extendidas en las cadenas de Hubbard utilizando fermiones ultrafríos.
Esto proporciona una nueva vía experimental para investigar la compleja relación entre el magnetismo y el dopaje en sistemas de electrones correlacionados.
Los hallazgos son significativos para avanzar en la comprensión de la superconductividad a alta temperatura.

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