ترغب بنشر مسار تعليمي؟ اضغط هنا

Enhanced Shot Noise in Tunneling through a Stack of Coupled Quantum Dots

241   0   0.0 ( 0 )
 نشر من قبل Patrick Barthold
 تاريخ النشر 2006
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

We have investigated the noise properties of the tunneling current through vertically coupled self-assembled InAs quantum dots. We observe super-Poissonian shot noise at low temperatures. For increased temperature this effect is suppressed. The super-Poissonian noise is explained by capacitive coupling between different stacks of quantum dots.



قيم البحث

اقرأ أيضاً

The shot noise suppression in a sample containing a layer of self-assembled InAs quantum dots has been investigated experimentally and theoretically. The observation of a non-monotonic dependence of the Fano factor on the bias voltage in a regime whe re only few quantum dot ground states contribute to the tunneling current is analyzed by a master equation model. Under the assumption of tunneling through states without Coulomb interaction this behaviour can be qualitatively reproduced by an analytical expression.
We report measurements of the nonlinear conductance of InAs nanowire quantum dots coupled to superconducting leads. We observe a clear alternation between odd and even occupation of the dot, with sub-gap-peaks at $|V_{sd}|=Delta/e$ markedly stronger( weaker) than the quasiparticle tunneling peaks at $|V_{sd}|=2Delta/e$ for odd(even) occupation. We attribute the enhanced $Delta$-peak to an interplay between Kondo-correlations and Andreev tunneling in dots with an odd number of spins, and substantiate this interpretation by a poor mans scaling analysis.
We present a new scheme to detect the quantum shot noise in coupled mesoscopic systems. By applying the noise thermometry to the capacitively coupled quantum point contacts (QPCs) we prove that the noise temperature of one QPC is in perfect proportio n to that of the other QPC which is driven to non-equilibrium to generate quantum shot noise. We also found an unexpected effect that the noise in the source QPC is remarkably suppressed possibly due to the cooling effect by the detector QPC.
135 - K. Shibata , C. Buizert , A. Oiwa 2007
We have fabricated superconductor-quantum dot-superconductor (SC-QD-SC) junctions by using SC aluminum electrodes with narrow gaps laterally contacting a single self-assembled InAs QD. The fabricated junctions exhibited clear Coulomb staircases and C oulomb oscillations at 40 mK. Furthermore, clear suppression in conductance was observed for the source-drain voltage $|V_{rm SD}| < 2Delta/e$, where $Delta$ is the SC energy gap of Al. The absence of Josephson current that flows through QDs is due to the strong Coulomb interaction and non-negligible thermal fluctuation in our measurement system.
156 - I. Weymann , J. Barnas 2007
Spin-dependent transport through a multilevel quantum dot weakly coupled to ferromagnetic leads is analyzed theoretically by means of the real-time diagrammatic technique. Both the sequential and cotunneling processes are taken into account, which ma kes the results on tunnel magnetoresistance (TMR) and shot noise applicable in the whole range of relevant bias and gate voltages. Suppression of the TMR due to inelastic cotunneling and super-Poissonian shot noise have been found in some of the Coulomb blockade regions. Furthermore, in the Coulomb blockade regime there is an additional contribution to the noise due to bunching of cotunneling processes involving the spin-majority electrons. On the other hand, in the sequential tunneling regime TMR oscillates with the bias voltage, while the current noise is generally sub-Poissonian.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا