Quantum energetics of a non-commuting measurement

TL;DR

This paper experimentally investigates the energy transfer mechanisms during non-commuting quantum measurements using a circuit QED system, revealing how measurement affects system energetics and providing insights into quantum measurement foundations.

Contribution

It presents the first experimental analysis of energy exchange in non-commuting quantum measurements within a circuit QED setup, highlighting spectral shifts linked to energy transfer.

Findings

Spectral analysis shows frequency shifts in cavity photons during measurement.

Energy transfer between qubit and meter is balanced with observed spectral shifts.

Provides new insights into quantum measurement energetics and foundational principles.

Abstract

When a measurement observable does not commute with a quantum system's Hamiltonian, the energy of the measured system is typically not conserved during the measurement. Instead, energy can be transferred between the measured system and the meter. In this work, we experimentally investigate the energetics of non-commuting measurements in a circuit quantum electrodynamics system containing a transmon qubit embedded in a 3D microwave cavity. We show through spectral analysis of the cavity photons that a frequency shift is imparted on the probe, in balance with the associated energy changes of the qubit. Our experiment provides new insights into foundations of quantum measurement, as well as a better understanding of the key mechanisms at play in quantum energetics.