Single qubit measurements with an asymmetric single-electron transistor

TL;DR

This paper explores the efficiency of asymmetric single-electron transistors (SETs) in qubit measurements, demonstrating their near-ideal detection capabilities and comparing their decoherence effects with point-contact detectors.

Contribution

It introduces the use of asymmetric SETs for qubit measurement, showing they outperform symmetric SETs and approach ideal detection in high asymmetry regimes.

Findings

Asymmetric SETs are more efficient than symmetric ones.

Large asymmetry in SETs yields near-ideal measurement performance.

Comparison with point-contact detectors clarifies the link between information gain and decoherence.

Abstract

We investigate qubit measurements using a single electron transistor (SET). Applying the Schr\"odinger equation to the entire system we find that an asymmetric SET is considerably more efficient than a symmetric SET. The asymmetric SET becomes close to an ideal detector in the large asymmetry limit. We also compared the SET detector with a point-contact detector. This comparison allows us to illuminate the relation between information gain in the measurement process and the decoherence generated by these measurement devices.