If you would like to join via online, please register from here
https://hasegawa.issp.u-tokyo.ac.jp/nanoscience-seminar-registration-form

Addressability to individual atoms and atom-by-atom position control using a scanning tunneling microscope (STM) [1] opens the bottom-up design of functional quantum devices. As an extension of such potential to atomic/molecular spins, STM can provide a platform of solid state qubits [2,3], which is unique in the sense of bottom-up design of qubit systems of a scale ~1 nm, with advantage of atom precision control of structure and inter-qubit couplings [4]. Here, I first introduce a recent advance of STM by combining conventional electron spin resonance (ESR), which picks up the advantages of the two techniques, high spatial resolution of STM and high energy resolution of ESR, enabling to drive and detect spin resonance of individual atoms on surfaces. Then, I continue a successful implementation of pulsed-ESR into STM to coherently control individual atomic [5] and molecular [6] spins on surface, paving a way towards on-surface electron spin qubits at the atomic scale. So far, the quantum coherence of such spin qubits is limited by ≲ 100 ns, requiring a noticeable improvement for their practical applications. In this regard, I briefly suggest some feasible ideas to protect such spin qubits from the environmental decoherence, to narrow down the direction and brighten a way to raise the on-surface qubits up to a stage of the quantum-coherent applications [4].
References:
[1] D. M. Eigler, E. K. Schweizer, Nature 344, 524–526 (1990).
[2] A. J. Heinrich et al. Nat. Nanotechnol. 16, 1318–1329 (2021).
[3] S. Thiele et al. Science 344, 1135-1138 (2014).
[4] Y. Wang et al. arXiv:2108.09880; under review (2022).
[5] K. Yang et al. Science 366, 509-512 (2019).
[6] P. Willke et al. ACS Nano 15, 17959–17965 (2021).