Optimization of island size in single electron tunneling devices: Experiment and theory

Abstract

We have investigated the influence of island size on the operation of single electron tunneling (SET) devices. The self-heating, self-capacitance, and charge noise have been determined for six SET transistors with island sizes varying from 0.17×0.17 μm2 to 5×5 μm2. The I–V characteristics of these devices can be well fit to a model where the heat flow from the device is limited by the electron-phonon coupling. The best fit to this model was obtained with an electron-phonon coupling parameter of Σ=0.3×109 W K−5 m−3. We have found a clear indication that the charge noise of our SET transistors, which are fabricated with the usual techniques, increases with increasing island size. These results have been used to estimate the thermal error of a single electron turnstile assuming that self-heating and charge noise in the turnstile are the same as in our SET transistors. The accuracy of the turnstile is dramatically reduced by the self-heating and the charge noise.

Josephson charge qubits: a brief review

“…The parameter α has been obtained from the dc transport measurements for a device with essentially same geometry and fabrication process, and has been found to be α = (1.3 × 10 −3 e) 2 . This value is consistent with what was reported in other works [43][44][45], and also with the value derived from T 2 . Figure 6 summarizes the reduced noise spectrum S E derived from the measured 1 according to Eq.…”

“…1/ f charge noise is very common in single-electron devices and is usually attributed to random motion of charges either in the substrate or the junction barrier, although the exact mechanism is still not known [43][44][45]. Indeed, the sample studied here also showed 1/ f noise when the dc current through the probe junction was measured.…”

NbSi nanowire quantum phase-slip circuits: dc supercurrent blockade, microwave measurements, and thermal analysis

“…Roukes et al 41 Cu 2 × 10 9 Cu-on-sapphire 125 Nahum and Martinis 42 Cu 3.7 × 10 9 Verbrugh et al 43 Al 0.2 to 0.5 × 10 9 Al-on-Si 100 Covington et al 44 AuPd 1.4 × 10 9…”

Charge noise in single-electron transistors and charge qubits may be caused by metallic grains

“…The barrier dielectric has been proposed as location of the charge traps by several groups. 14,19,22,26 Several groups have shown that the low-frequency noise at the output of the SET varies with the current gain ͑‫ץ‬I / ‫ץ‬Q g ͒ of the SET and that the maximum noise is found at the bias point with maximum gain. [20][21][22] This indicates that the noise sources acts at the input of the device, i.e., as an external fluctuating charge.…”

“…Even though there have been many efforts 14,15,[17][18][19][20][21][22][23][24] to reveal the physical origin of the background charge fluctuators, the nature of these fluctuators is still unknown. It is not even clear where these fluctuators are located.…”