Complete control of a matter qubit using a single picosecond laser pulse

Abstract

We demonstrate for the first time that a matter physical two level system, a qubit, can be fully controlled using one ultrafast step. We show that the spin state of an optically excited electron, an exciton, confined in a quantum dot, can be rotated by any desired angle, about any desired axis, during such a step. For this we use a single, resonantly tuned, picosecond long, polarized optical pulse. The polarization of the pulse defines the rotation axis, while the pulse detuning from a non-degenerate absorption resonance, defines the magnitude of the rotation angle. We thereby achieve a high fidelity, universal gate operation, applicable to other spin systems, using only one short optical pulse. The operation duration equals the pulse temporal width, orders of magnitude shorter than the qubit evolution life and coherence times.

main text: 4 pages, 3 figures Supplemental material: 3 pages, 1 figure

References in corpus (5)

• Quantum Computing
• Driven coherent oscillations of a single electron spin in a quantum dot
• Ultrafast optical control of entanglement between two quantum dot spins
• Fast optical preparation, control and read-out of single quantum dot spin
• Theory of fast optical spin rotation in a quantum dot based on geometric phases and trapped states

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• Quantitative analysis of quantum dot dynamics and emission spectra in cavity quantum electrodynamics
• Charge tuning in [111] grown GaAs droplet quantum dots
• Ultrafast Coherent Manipulation of Trions in Site-Controlled Nanowire Quantum Dots