A light-hole exciton in a quantum dot

Abstract

A light-hole exciton is a quasiparticle formed from a single electron bound to a single light hole. This type of fundamental excitation, if confined inside a semiconductor quantum dot, could be advantageous in quantum information science and technology. However, it has been difficult to access it so far, because confinement and strain in conventional quantum dots favour a ground-state single-particle hole with a predominantly heavy-hole character. Here we demonstrate the creation of a light-hole exciton ground state by applying elastic stress to an initially unstrained quantum dot. Its signature is clearly distinct from that of the well-known heavy-hole exciton and consists of three orthogonally polarized bright optical transitions and a fine-structure splitting of hundreds of microelectronvolts between in-plane and out-of-plane components. This work paves the way for the exploration of the fundamental properties and of the potential relevance of three-dimensionally confined light-hole states in quantum technologies.

Decay dynamics and exciton localization in large GaAs quantum dots grown by droplet epitaxy

“…47 The presence of a finite in-plane confinement, as is the case for small aspectratio QDs, induces a small contribution from the light-hole band, which can be neglected for practical purposes. 45 …”

Single photon emission up to liquid nitrogen temperature from charged excitons confined in GaAs-based epitaxial nanostructures

“…The unique structure of CQDs makes it possible to tailor the built-in strain field and the quantum confinement. 23,24 This in turn can allow manipulating the emitter properties via intentionally forming the light-hole exciton, for instance, enabling the control of the polarization properties, 25,26 engineer the exciton dipole moment 25 crucial for optical Stark effect tuning, 27 or it could lead to the reduction of the exciton fine structure splitting. 28 Consequently, it may be possible to consider a CQD structure not only as a well-controlled single photon emitter with broad range of tunable parameters but also as a potential source of polarization-entangled photon pairs.…”

Pontos quânticos ambientalmente amigáveis: destaque para o óxido de zinco

“…A Figura 1 ilustra a densidade de estados partindo de um material massivo, tridimensional (a) e que, progressivamente, sofre o confinamento em uma das dimensões (b)-(d). 5 QDs podem confinar transportadores de cargas e manter uma coerência de spin destes transportadores em um período de tempo maior que os correspondentes materiais massivos, característica essa fundamental para o desenvolvimento de tecnologia baseada em sistemas quânticos 6 e da manifestação de efeitos excitônicos expressivos, os quais dependem da forma e tamanho da estrutura de confinamento. 7 A incidência de radiação eletromagnética, com comprimento de onda coincidente com o espectro de absorção do QD, pode promover um elétron para a banda de condução, gerando um buraco (teoricamente uma partícula que apresenta carga de sinal oposto ao do elétron) na banda de valência.…”