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International Journal of Modern Physics B

EVOLUTION OF SPIN OF A QUANTUM DOT EMBEDDED IN A SUPERCONDUCTING RING

Jun Feng, S. L. REN, Chun-Hong Jiao, Bin Qian, An Hu, Xiaoshan Wu

Published Jul 30, 2007• 0 citations
Publisher

Abstract

We study the spin oscillations of a quantum dot (QD) embedded in a superconducting ring. The dot is characterized by the Coulomb interaction and the gate voltage. The pairing potential is considered in the superconducting ring. We found that the amplitude and frequency of the oscillations depend sensitively on the pairing potential of superconducting lead, the coupling strength between the dot and superconducting lead. We also show that the magnetic moment on the dot can be controlled by changing the pairing potential of superconducting lead.

DOI
10.1142/s0217979207044068

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We consider a single localized spin-1/2 placed between singlet superconducting leads of a Josephson junction inserted in a superconducting ring, subject to a dc magnetic field B || z. Turning on the tunneling or a time-dependent flux in a superconducting ring, induces oscillations of the Josephson current, with an amplitude sensitive to the initial value of the z-component of the spin, Sz = ±1/2, which allows for a measurement of the initial spin state. At low temperatures when effects of quasiparticles are negligible, this procedure realizes a quantum-non-demolition (QND) measurement of Sz.
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