High sensitivity charge detection and dephasing in edge state interferometer

We present an interferometry model of high sensitivity and high efficiency charge detectors in the integer quantum Hall regime. We show that the charge sensitivity in Fabry–Perot interferometer is higher than a Mach–Zehnder interferometer due to multiple reflections of electrons at quantum point contacts. We report the possibility of tuning Fabry–Perot interferometer for quantum limited detection for two quantum point contacts having different reflection probabilities. For systems with one quantum point contact and with two point contacts, we discuss improvement in sensitivity using electrons in spin entangled singlet pairs, injected through identically biased input terminals.