K. C. Hall
Femtosecond pulse shaping provides a flexible approach to tailoring the Hamiltonian governing the interaction of light with matter. Together with powerful adaptive feedback algorithms, this approach is now used routinely in the control of a variety of physical processes. For quantum computing applications, pulse shaping provides a means to optimize the speed and fidelity of elementary quantum gates, and may enable the realization of schemes for complex instruction set quantum computing. In this presentation, I will discuss our recent experiments demonstrating ultrafast quantum control of charge based (exciton) qubits in semiconductor quantum dots. Using optimal quantum control techniques, we show that pulse shaping provides a means to optimize the fidelity of a C-ROT gate in single quantum dots [1,2], and enables parallel single qubit gates on distant quantum dots within the laser focal spot . We also demonstrate adiabatic rapid passage on a subpicosecond time scale in single semiconductor quantum dots, yielding new insight into the role of phonons in dephasing of exciton qubits .
1. A. Gamouras, R. Mathew, and K. C. Hall, J. Appl. Phys. 112, 014313 (2012).
2. R. Mathew, C. E. Pryor, M. E. Flatte, and K. C. Hall, Phys. Rev. B 84, 205322 (2011).
3. A. Gamouras, R. Mathew, S. Freisem, D. G. Deppe, and K. C. Hall, Nano Letters 13, 4666 (2013).
4. R. Mathew, E. Dilcher, A. Gamouras, A. Ramachandran, Hong Yi Shi Yang, Sabine Freisem, Dennis Deppe, and Kimberley C. Hall, Phys. Rev. B 90, 035316 (2014).