Bounding the Minimum Time of a Quantum Measurement

TL;DR

This paper derives fundamental lower bounds on the minimum time required for quantum measurements, considering environmental interactions, and explores how these bounds depend on entropy change, measurement outcomes, and interaction strength.

Contribution

It introduces a framework incorporating environment interactions to establish lower bounds on quantum measurement times, a novel approach in quantum measurement theory.

Findings

Lower bounds scale with entropy change during measurement.

Bounds decrease with more measurement outcomes.

Environmental interaction strength influences measurement time.

Abstract

Measurements take a singular role in quantum theory. While they are often idealized as an instantaneous process, this is in conflict with all other physical processes in nature. In this Letter, we adopt a standpoint where the interaction with an environment is a crucial ingredient for the occurrence of a measurement. Within this framework, we derive lower bounds on the time needed for a measurement to occur. Our bound scales proportionally to the change in entropy of the measured system, and decreases as the number of of possible measurement outcomes or the interaction strength driving the measurement increases. We evaluate our bound in two examples where the environment is modelled by bosonic modes and the measurement apparatus is modelled by spins or bosons.