Generalized partial measurements

TL;DR

This paper introduces generalized partial measurements in quantum systems, demonstrating their probabilistic reversibility for all events and analyzing their implications for quantum tomography and superconducting qubit implementations.

Contribution

It extends the concept of partial measurements to a more general form that can be reversed probabilistically for both switching and non-switching events.

Findings

Generalized partial measurements can be reversed probabilistically for all events.

The Fisher information for these measurements is calculated, informing quantum tomography.

Two implementation methods with superconducting qubits are proposed.

Abstract

We introduce a type of measurements that generalize the so-called "partial measurements" performed in recent years with phase qubits. While in the case of partial measurements it has been demonstrated that one could undo the effect of the measurement only for non-switching events, we show here that generalized partial measurements can be reversed probabilistically for both switching and non-switching events. We calculate the associated Fisher information and discuss the estimation sensitivity for quantum tomography. Two ways of implementing this type of measurements with superconducting qubits are proposed.