Postponing the choice: advantage of deferred measurements in quantum information processing

TL;DR

This paper investigates the advantages of delaying measurement choices in quantum information processing, showing that under certain conditions, postponement can avoid additional costs and improve measurement strategies.

Contribution

It introduces the concept of deferred measurement choices and analyzes their benefits, highlighting scenarios where postponement offers no extra cost or is equivalent to full postponement.

Findings

Postponing measurement choices can be cost-effective in quantum systems.

Deferred decisions can sometimes match the performance of immediate measurements.

The advantage depends on assumptions about future measurement choices.

Abstract

Simultaneously implementing two arbitrary quantum measurements on the same system is impossible. The consequence of this limitation is that selecting one measurement actively excludes other possibilities. Two incompatible choices can then be forced together only at the cost of adding enough noise to the measurements. An intriguing alternative is to postpone the choice, or part of it, until a later stage. We explore the advantages of this deferred decision-making and discover that the benefits critically depends on the assumptions about the forthcoming choice. In certain scenarios postponing the choice introduces no additional cost, while in others partial postponement can be effectively the same as full postponement.