We evaluate the detector nonideality (and energy sensitivity) of a normal-state single-electron transistor (SET) in the cotunneling regime in a two-charge-state approximation. For small conductances and at zero temperature, the SET's performance as a charge-qubit readout device is characterized by a universal one-parameter function. The result shows that near-ideal, quantum-limited measurement is possible for a wide range of small bias voltages. However, near the threshold voltage for crossover to sequential tunneling, the device becomes strongly nonideal. The (symmetrized) current-charge cross-correlation vanishes for low frequencies, causing two different definitions of detector nonideality to agree. Interpretations of these findings are discussed.
@article{arxiv.cond-mat/0009163,
title = {Quantum-efficient charge detection using a single-electron transistor},
author = {Alec Maassen van den Brink},
journal= {arXiv preprint arXiv:cond-mat/0009163},
year = {2015}
}
Comments
REVTeX, 4 pages, no figures; discussion expanded, $\epsilon$-$\eta$ relation corrected below (10); subm. to PRL