Writing, Reading and controlling the state of SINGLE Matter-SPINS using A SINGLE, picosecond-Long, laser PULSE

The ability to coherently control matter qubits is essential for realizations of quantum information processing.

In general, quantum information processing requires ability to write, read and control qubit states with high

fidelity, much faster than the qubit's life- and coherence-times. We demonstrate these abilities, for the first

time, by applying sequences of three resonant picosecond laser pulses to single semiconductor quantum dots,

where the matter-qubit is formed by the two-spin-states of a single, quantum-confined, electron-hole pair. 

The first pulse transfers the pulse polarization to the spin state of the pair, demonstrating a one to one correspondence

between the polarization's Poicare's sphere and the spin's Bloch sphere. The second pulse rotates the spin state on its Bloch sphere. 

The third pulse 'reads' the spin state by measuring the spin's projection on the pulse's polarization direction. 

We demonstrate three degrees of freedom in rotating the matter-spin state. This allows implementation

of a universal gate by one optical pulse, only.

Parts of my talk can be found in:

[1] E. Poem et al," Accessing the dark exciton with light "Nature Physics 6, 993-997, (2010)

[2] Y. Benny, et al., Phys. Rev. Lett. 106, 040504, (2011)

[3] Y. Benny, et al "Two-photon- photoluminescence excitation spectroscopy of single quantum-dots" Phys. Rev. B. 84, 075473, (2011).

[4] E. Poem, et al "Optically induced rotation of a quantum dot exciton spin." Phys. Rev. Lett. 107, 087401, (2011).