Ultrafast control of donor-bound electron spins with single detuned optical pulses

Abstract

The ability to control spins in semiconductors is important in a variety of fields, including spintronics and quantum information processing. Due to the potentially fast dephasing times of spins in the solid state, spin control operating on the picosecond timescale, or faster, may be necessary. Such speedswhich are not possible to reach with standard electron spin resonance techniques based on microwave sourcescan be attained with broadband optical pulses. One promising ultrafast technique uses single broadband pulses detuned from resonance in a three-level system. This technique is robust against optical-pulse imperfections and does not require a fixed optical reference phase. Here we demonstrate, theoretically and experimentally, the principle of coherent manipulation of spins using this approach. Spin rotations with areas exceeding /4 for a single pulse and /2 for two pulses are achieved for donor-bound electrons. This technique might find applications from basic solid-state electron spin resonance spectroscopy to arbitrary single-qubit rotations and bang-bang control for quantumcomputation. © 2008 Macmillan Publishers Limited. All rights reserved.