Noninvasive Quantum Measurement of Arbitrary Operator Order by Engineered Non-Markovian Detectors

TL;DR

This paper introduces a theoretical framework for noninvasive quantum measurements involving engineered non-Markovian detectors, enabling the simultaneous measurement of non-commuting observables and proposing an experimental setup to explore these effects.

Contribution

It derives a compact formula for weak measurements with memory effects and proposes a tunable double-dot detector setup for experimental investigation of non-Markovian quantum measurements.

Findings

Derived a formula interpolating between instantaneous and continuous measurements.

Identified a system-mediated detector-detector interaction crucial for non-commuting observables.

Proposed a tunable double-dot detector setup for experimental exploration.

Abstract

The development of solid-state quantum technologies requires the understanding of quantum measurements in interacting, non-isolated quantum systems. In general, a permanent coupling of detectors to a quantum system leads to memory effects that have to be taken into account in interpreting the measurement results. We analyze a generic setup of two detectors coupled to a quantum system and derive a compact formula in the weak-measurement limit that interpolates between an instantaneous (text-book type) and almost continuous - detector dynamics-dependent - measurement. A quantum memory effect that we term system-mediated detector-detector interaction is crucial to observe non-commuting observables simultaneously. Finally, we propose a mesoscopic double-dot detector setup in which the memory effect is tunable and that can be used to explore the transition to non-Markovian quantum measurements experimentally.