Exchange statistics, charge detection and back-action dephasing by a mesoscopic beam collider

Abstract

We investigate properties of charge detection and detection-induced dephasing of a charge qubit interacting with an electron beam collider composed of a quantum point contact. We predict that the interference of the qubit is fully restored when the two inputs are identically biased so that all the electrons suffer two-electron collision, unlike the case without collision. This phenomenon is related to Fermi statistics and illustrates the peculiar nonlocality of dephasing. We also describe the detection properties of entangled electron pairs. For singlet pairs, the sensitivity of charge detection is enhanced which originates from the bunching behavior of electrons. This demonstrates that control of exchange statistics of particles can help sensitive charge detection.

Edge-state Fabry-Perot interferometer as a high-sensitivity charge detector

“…A high sensitivity charge detector working in the quantum limit can have wider applications in quantum metrology [9]. The improvements in measurements can be accomplished either through new designs of measurement devices or by developing methods that rely on properties like correlations [10] and entanglement [11,12].…”