We report strong heavy hole-light mixing in GaAs quantum dots grown by droplet epitaxy. Using the neutral and charged exciton emission as a monitor we observe the direct consequence of quantum dot symmetry reduction in this strain free system. By fitting the polar diagram of the emission with simple analytical expressions obtained from k·p theory we are able to extract the mixing that arises from the heavy-light hole coupling due to the geometrical asymmetry of the quantum dot. A large variety of promising applications for self assembled semiconductor quantum dots in photonics and spin electronics are based on the discreteness of the interband transitions [1] and on long carrier spin relaxation times [2,3]. Combining the two characteristics allows electrical tuning of the light polarization of single photon emitters based on quantum dots [4]. Optical preparation, manipulation and read-out of a single spin state [5][6][7][8] are governed by the optical selection rules [9,10]. For excitons based on pure angular momentum eigenstates for electrons (m s = ±1/2) and for heavy holes (m j = ±3/2), a given light polarization can be associated unambiguously with the optical creation of a certain spin state (solid arrows in the inset of Fig. 1). In the common case of [100] growth (defining the quantization axis z) the symmetry of the bulk semiconductor implies that the x and y axis, [110] and [110], are equivalent (D 2d ). The conduction electron is well described as an isotropic particle of spin ±1/2. In contrast, valence hole states are non-isotropic as the x-y equivalence is lifted in realistic dots due to strain and/or shape and in plane anisotropy [11]. Despite being separated in energy by tens of meV (∆ HL in the inset of Fig. 1), substantial mixing between valence heavy hole and light hole (HH-LH) states has been reported in strained II-VI and III-V quantum dots [11][12][13][14][15]. The resulting non pure selection rules in combination with long carrier relaxation times have allowed the implementation of very original, high fidelity (≥ 99%) electron and hole spin initialization schemes [16,17]. In addition, HH-LH mixing has been identified as the key parameter at the origin of the dipole-dipole nuclear spin mediated hole spin dephasing in quantum dots [14,18]. The dominant physical origin of HH-LH mixing has been attributed to lattice strain [11,12,19].This was our motivation to study strain free, individual GaAs/AlGaAs quantum dots by molecular droplet epitaxy [20][21][22][23], see [24] for alternative growth method. We performed detailed, angle dependent polarization analysis of the photoluminescence (PL) emitted parallel to the quantum dot growth direction. We observe, even in the absence of strain, strong evidence for HH-LH mixing revealed in the emission of the positively charged exciton X + (trion: 2 valence holes + 1 conduction electron) and the neutral exciton X 0 (1 hole + 1 electron). Our experiments show that (i) an asymmetry in the confinement potential due to quantum dot elongation (ii) the main axis ...