Suppression of Zeeman Gradients by Nuclear Polarization in Double Quantum Dots
We use electric dipole spin resonance to measure dynamic nuclear polarization in InAs nanowire quantum dots. The resonance shifts in frequency when the system transitions between metastable high and low current states, indicating the presence of nuclear polarization. We propose that the low and the high current states correspond to different total Zeeman energy gradients between the two quantum dots. In the low current state, dynamic nuclear polarization efficiently compensates the Zeeman gradient due to the g-factor mismatch, resulting in a suppressed total Zeeman gradient. We present a theoretical model of electron-nuclear feedback that demonstrates a fixed point in nuclear polarization for nearly equal Zeeman splittings in the two dots and predicts a narrowed hyperfine gradient distribution.
Additional Information© 2012 American Physical Society. Received 7 September 2012; published 5 December 2012. We thank M. Rudner, H. Bluhm, E. Rashba, Yu. Nazarov, L. Levitov, L. Vandersypen, and K. Nowack. This work has been supported by NWO/FOM (Netherlands Organization for Scientific Research), by the Alexander von Humboldt Foundation, and through the DARPA program QUEST.
Published - PhysRevLett.109.236805.pdf
Submitted - 1209.1510v1.pdf