Chinese Physics Letters

Enhancement of Quantum Current in Mesoscopic Coupled Rings

Yinghua Ji, Haimei Luo, Juju Hu, Liu Gang

Published Oct 27, 2004• 3 citations

Abstract

We discuss the relationship between external magnetic field and persistent currents of three mesoscopic-coupled rings with charge discreteness. Through numerical calculation and analysis, it is found that the properties of the persistent currents depend on both external magnetic flux and coupled factors. The positive coupling between the rings will decrease the persistent currents when 0< m <1 with m being the coupling coefficient. The quantum current magnification effect appearing in the rings is also investigated.

DOI: 10.1088/0256-307x/21/11/053

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Chinese Physics Letters

Enhancement of Quantum Current in Mesoscopic Coupled Rings

Yinghua Ji, Haimei Luo, Juju Hu, Liu Gang

Published Oct 27, 2004• 3 citations

Publisher

Abstract

DOI: 10.1088/0256-307x/21/11/053

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We investigate the effect of local charge detection in an Aharonov-Bohm ring composed of

N

identical coupled quantum dots. It is found that the single-electron persistent current of the ring is not fully suppressed in the limit of perfect charge detection except for the case of

N=2

. This property is analyzed for a single electron in the number-state representation. We point out that the nonvanishing persistent current can be understood in terms of the single-electron entanglement in the number-state representation. In addition, we find that the local charge detection may produce a finite persistent current even in the absence of the external magnetic fields.

Φ

while the bubble does not enclose any flux. The novelty of this work lies in the fact that while earlier current enhancement was observed in non-equilibrium systems (e.g., a ring coupled to two reservoirs at different chemical potentials

μ_{1}

and

μ_{2}

), herein we prove that current enhancement can also arise in equilibrium. In addition, we show that the closed system analog of our chosen open hybrid ring system violates parity effects. Finally, we bring to focus the discrepancy between the equilibrium magnetic moment (obtained via energy eigenvalues) and that calculated from the currents in the system.