Ultrafast optical spin echo for electron spins in semiconductors

Area of Science:

• Quantum Information Science
• Condensed Matter Physics
• Optical Spectroscopy

Background:

• Spin-based quantum computing and magnetic resonance require accurate measurement of spin system coherence time, T(2).
• Existing microwave-based spin echo techniques face limitations with systems exhibiting fast dephasing times (T_{2};{*}) compared to microwave control timescales.

Purpose of the Study:

• To experimentally implement an all-optical spin echo technique for determining the T(2) time of a semiconductor electron-spin system.
• To demonstrate a method for overcoming limitations of traditional microwave-based techniques for measuring T(2) in fast-dephasing systems.

Main Methods:

• Utilized three ultrafast optical pulses to achieve arbitrary spin rotation.
• Measured spin echo signal amplitude as a function of the time delay between optical pulses.
• Implemented an all-optical spin echo sequence for coherence time T(2) determination.

Main Results:

• Successfully demonstrated the all-optical spin echo technique on a semiconductor electron-spin system.
• Obtained clean T(2) measurements, particularly effective for systems with dephasing times (T_{2};{*}) faster than microwave control.
• Validated the capability of ultrafast optical pulses for precise spin coherence time measurements.

Conclusions:

• The all-optical spin echo method provides a viable alternative to microwave techniques for T(2) measurements in challenging spin systems.
• This advancement is a significant step towards developing ultrafast optical dynamic decoupling for spin-based qubits.
• Enables more accurate characterization of spin systems crucial for advancing quantum computing and magnetic resonance applications.