152 research outputs found
Probing local electronic states in the quantum Hall regime with a side coupled quantum dot
We demonstrate a new method for locally probing the edge states in the
quantum Hall regime utilizing a side coupled quantum dot positioned at an edge
of a Hall bar. By measuring the tunneling of electrons from the edge states
into the dot, we acquire information on the local electrochemical potential and
electron temperature of the edge states. Furthermore, this method allows us to
observe the spatial modulation of the electrostatic potential at the edge state
due to many-body screening effect.Comment: 5 pages, 5 figure
Suppression of Pulsed Dynamic Nuclear Polarization by Many-Body Spin Dynamics
We study a mechanism by which nuclear hyperpolarization due to the
polarization transfer from a microwave-pulse-controlled electron spin is
suppressed. From analytical and numerical calculations of the unitary dynamics
of multiple nuclear spins, we uncover that, combined with the formation of the
dark state within a cluster of nuclei, coherent higher-order nuclear spin
dynamics impose limits on the efficiency of the polarization transfer even in
the absence of mundane depolarization processes such as nuclear spin diffusion
and relaxation. Furthermore, we show that the influence of the dark state can
be partly mitigated by introducing a disentangling operation. Our analysis is
applied to the nuclear polarizations observed in C nuclei coupled with a
single nitrogen-vacancy center in diamond [Science 374, 1474 (2021) by J.
Randall et al.]. Our work sheds light on collective engineering of nuclear
spins as well as future designs of pulsed dynamic nuclear polarization
protocols
Detection of spin polarization with a side coupled quantum dot
We propose realistic methods to detect local spin polarization, which utilize
a quantum dot side coupled to the target system. By choosing appropriate states
in the dot, we can put spin selectivity to the dot and detect spins in the
target with small disturbance. We also present an experiment which realizes one
of the proposed spin detection schemes in magnetic fields.Comment: 5 pages, 6 figure
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