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Probing quantum spin glass like system with a double quantum dot
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Koh, C. Y., & Kwek, L. C. (2016). Probing quantum spin glass like system with a double quantum dot. Journal of Magnetism and Magnetic Materials, 407, 314–320.
We study the ground state properties of a 4-qubit spin glass like (SGL) chain with probes at the end of the chain and compare our results with the non-spin glass like (NSGL) case. The SGL is modeled as a spin chain with nearest-neighbor couplings, taking on normal variates with mean J and variance Δ2. The entanglement between the probes is used to detect any discontinuity in the ground state energy spectrum.
For the NSGL case, it was found that the concurrence of the probes exhibits sharp transitions whenever there are abrupt changes in the energy spectrum. In particular, for the 4-qubit case, there is a sudden change in the ground state energy at an external magnetic fi eld B of around 0.66 (resulting in a drop in concurrence of the probes) and 1.7 (manifest as a spike). The latter spike persists for fi nite temperature case. For the SGL sample with sufficiently large Δ , however, the spike is absent. Thus, an absence in the spike could act as a possible signature of the presence of SGL eff ects. Moreover, the sudden drop in concurrence at B ≈ 0:66 does not disappear but gets smeared with increasing Δ. However, this drop can be accentuated with a smaller probe coupling. The finite temperature case is also briefly discussed.
This is the final draft, after peer-review, of a manuscript published in Journal of Magnetism and Magnetic Materials. The published version is available online at
0304-8853 (print)
1873-4766 (online)
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