Multiple-time states and multiple-time measurements in quantum mechanics

TL;DR

This paper introduces a novel formalism in quantum mechanics using multi-time states and measurements to better describe complex experimental setups involving multiple preparations and measurements, and explores implications for the flow of time.

Contribution

It presents the concept of multi-time quantum states and measurements, establishing a new framework that treats states and operators equivalently and addresses temporal flow issues.

Findings

Multi-time states effectively describe complex quantum experiments.

Multi-time measurements are formally related to multi-time states.

The approach offers new insights into the nature of quantum temporal evolution.

Abstract

We discuss experimental situations that consist of multiple preparation and measurement stages. This leads us to a new approach to quantum mechanics. In particular, we introduce the idea of multi-time quantum states which are the appropriate tools for describing these experimental situations. We also describe multi-time measurements and discuss their relation to multi-time states. A consequence of our new formalism is to put states and operators on an equal footing. Finally we discuss the implications of our new approach to quantum mechanics for the problem of the flow of time.