Classicality and amplification in postselected weak measurement

TL;DR

This paper explores the concept of anomalous weak amplification (AWA) in quantum measurements, clarifies the relationships between recent schemes, and presents a generalized framework for postselected AWA involving orthogonal states.

Contribution

It introduces a unified framework for AWA via postselection of orthogonal states, connecting recent disparate schemes and clarifying their underlying principles.

Findings

Identifies relationships between recent AWA schemes

Proposes a generalized framework for postselected AWA

Clarifies the role of interference and postselection in amplification

Abstract

Nearly thirty years ago the possibility of anomalous weak amplfication (AWA) was revealed by Aharonov, Albert and Vaidman [1]. Recently two papers presents two AWA schemes which are beyond the traditional proposal given by them [14, 15]. At the first glance the two papers seems very different. Ref. [14] discusses the thermal light cross-Kerr effect and finds only postselection can give the amplification effect without interference of the postselected meter states, and Ref. [15] shows that only weak interaction itself can give the amplification effect without postselection. Here the relationships between the two papers are pointed out and a generalized framework for AWA via postselecting a pair of orthogonal final states is shown.