Coherent Optical Control of single hole spin

Context of project
​The achievement of a highly coherent and robust qubit is perhaps the main milestone in the race for the development of quantum information technologies. Early on, it was recognized that single carrier spins in III-V semiconductor quantum dots offer a very attractive technological platform, as well as properties for robust operation and optical accessibility. Naturally, the electron spin emerged as the primary candidate, however, the decoherence induced by the nuclear spin environment limits drastically its capabilities. Interestingly, the interaction between hole spins and nuclear spins is about 10% of that with the electrons. The caveat here is to find the appropriate material system or conditions to isolate and optically control a single hole spin.        

Review on coherent optical control of spin states in semiconductor quantum dots ref:
[1] iopscience.iop.org/article/10.1088/0268-1242/25/10/103001/meta

Our work 
[1] We demonstrate coherent optical control of a single hole spin confined to an InAs/GaAs quantum dot. A superposition of hole-spin states is created by fast (10–100 ps) dissociation of a spin-polarized electron hole pair. Full control of the hole spin is achieved by combining coherent rotations about two axes: Larmor precession of the hole spin about an external Voigt geometry magnetic field, and rotation about the optical axis due to the geometric phase shift induced by a picosecond laser pulse resonant with the hole trion transition.  

Read more:
​Coherent optical control of the spin of a single hole in an InAs/GaAs quantum dot
T.M. Godden, J.H. Quilter, A.J. Ramsay, Y. Wu, P. Brereton, S.J. Boyle, I.J. Luxmoore, J. Puebla-Nunez, A.M. Fox, M.S. Skolnick
Physical review letters 108 (1), 017402 (2012)
journals.aps.org/prl/abstract/10.1103/PhysRevLett.108.017402
arXiv: arxiv.org/abs/1106.6282​
Personal contribution: Device fabrication and device operation advice during experiments

[2] The preparation of a coherent heavy-hole spin via ionization of a spin-polarized electron-hole pair in an InAs/GaAs quantum dot in a Voigt geometry magnetic field is experimentally investigated. For a dot with a typical bright-exciton fine-structure splitting of 17μeV, the fidelity of the spin preparation is limited to 0.75, with optimum preparation occurring when the effective fine structure of the bright exciton matches the in-plane hole Zeeman energy. In principle, higher fidelities can be achieved byminimizing the bright-exciton fine-structure splitting.

Fast preparation of a single-hole spin in an InAs/GaAs quantum dot in a Voigt-geometry magnetic field
T.M. Godden, J.H. Quilter, A.J. Ramsay, Y. Wu, P. Brereton, I.J. Luxmoore, J. Puebla, A.M. Fox, M.S. Skolnick
Physical Review B 85 (15), 155310 (2012)
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.85.155310 
​Personal contribution: Device fabrication and device operation advice during experiments