Weak continuous measurements require more work than strong ones

Abstract

Understanding the energy cost of quantum measurement process and its connection to the measurement performance faces the challenge of modeling the objectification process. The latter, turns the measurement result into an objective fact, available to independent observers, and is responsible for the measurement irreversibility. To address this issue, we propose and analyze a dynamical model of quantum measurement, able to capture nonideal (weak and inefficient) measurements. In this model, the objectification is induced by a contact with a macroscopic reservoir at equilibrium which is responsible for the redundant broadcast of the measurement outcome (producing a Spectrum Broadcast Structure (SBS) state) while inducing decoherence in the pointer basis, in the line of the theory of quantum Darwinism. We analyze the performance of the obtained measurement process by introducing figures of merit to quantify the strength of the measurement and its efficiency. We also derive and a lower bound on the measurement work cost that we can relate to the measurement quality. We take as an illustration the readout of a qubit via its coupling to a harmonic oscillator. We investigate the long sequences of extremely short and weak measurements (a.k.a continuous measurements), to find under which conditions they converge to an ideal (projective) measurement and analyze their work cost. Surprisingly, we find that a sequence converging to projective measurement has a much larger work cost than an equivalent strong measurement obtained from a single intense interaction with the apparatus. We extend this result to a large class of models owing to scaling arguments. Our analysis offers new insights into the trade-offs between measurement strength, energy consumption, and information extraction in quantum measurement protocols.

References in corpus (27)

• Quantum sensing
• Advances in Quantum Cryptography
• A Straightforward Introduction to Continuous Quantum Measurement
• Quantum Darwinism
• Entropy production as correlation between system and reservoir
• Minimal Energy Cost for Thermodynamic Information Processing: Measurement and Information Erasure
• Observing single quantum trajectories of a superconducting qubit
• Understanding quantum measurement from the solution of dynamical models
• Quantum Measurement Cooling
• Efficient Quantum Measurement Engine
• Ideal Projective Measurements Have Infinite Resource Costs
• Quantum work and the thermodynamic cost of quantum measurements
• Quantum origins of objectivity
• Dynamics of a qubit while simultaneously monitoring its relaxation and dephasing
• Work estimation and work fluctuations in the presence of non-ideal measurements
• Optimizing resource efficiencies for scalable full-stack quantum computers
• Quantum measurement engines and their relevance for quantum interpretations
• What Quantum Measurements Measure
• Quantum Trajectories for Realistic Detection
• Thermodynamics of decoherence
• Efficiency at maximum power of a Carnot quantum information engine
• A generic model for quantum measurements
• A thermodynamically consistent approach to the energy costs of quantum measurements
• Thermodynamically free quantum measurements
• Classicality of the heat produced by quantum measurements
• Fundamental mechanisms of energy exchanges in autonomous measurements based on dispersive qubit-light interaction
• Equilibration of objective observables in a dynamical model of quantum measurements