Characterizing Temperature and Strain Variations with Qubit Ensembles for Their Robust Coherence Protection

Area of Science:

• Quantum information science
• Solid-state physics
• Materials science

Background:

• Solid-state spin defects, particularly nuclear spins, show promise for quantum memories and sensors due to long coherence times.
• Dephasing caused by variations in quadrupole and hyperfine interactions currently limits their performance.

Purpose of the Study:

• To introduce an unbalanced echo technique for overcoming dephasing in nuclear spins.
• To enable the use of nuclear spins as robust quantum memories and sensors.
• To develop methods for probing material properties like temperature and strain.

Main Methods:

• Proposed an unbalanced echo sequence utilizing a second spin to refocus interaction variations.
• Developed first-principles methods to predict interaction variations and their correlations.
• Conducted experiments on nuclear spins in diamond to validate the technique.

Main Results:

• Achieved a 20-fold increase in dephasing time in a diamond nuclear spin ensemble.
• Demonstrated the potential for the unbalanced echo to probe temperature and strain distributions.
• Numerical simulations confirmed the method's ability to refocus stronger noise variations.

Conclusions:

• The unbalanced echo technique effectively enhances coherence times in solid-state nuclear spins.
• This method opens new avenues for high-performance quantum memories, sensors, and material characterization.
• Further research can explore refocusing even more significant noise variations.