12 December 2024 Thu 3.30 pm

Scanning tunneling microscopy (STM) combined with electron spin resonance (ESR) enables a coherent control of atomic spins on surfaces. Recently, introduction of a 'remote' spin [1], which is free from the tunneling-induced scattering, has shown a spin relaxation time (T1) significantly improved, but still limited by strong substrate scattering [2]. Here, we report an ESR-STM study on the spin relaxation of coupled Ti atoms (S = 1/2) on 3 ML MgO. A remote Ti showed T1 of ~10 mus, longer by 2 orders of magnitude than remote Ti on 2 ML MgO, which is well understood by the enhanced decoupling from the substrate. However, a sensor spin’s dynamics strongly governed by scattering with tip and tunneling current, revealing T1 of ~100 ns [3]. Tip generates an unbalance in dynamics of coupled Ti spins by introducing strong dissipation at sensor side. The present work shows that by tuning energy levels in the quantum system, the remote spin dynamics can be decoupled from sensor spin or strongly influenced via an exchange interaction between coherent states. This study is essential for quantum information processing and quantum simulation exploiting such two qubits in unbalanced environment.

References:

[1] S. Phark et al. ACS Nano 17, 14144–14151 (2023).

[2] Y. Wang et al. Science 382, 6666 (2023).

[3] W. Paul et al. Nature Phys. 13, 403–407 (2017).

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