Differential Microcalorimetry of Quantum Readout: Isolating Record-Formation Dissipation from Readout-Chain Heating

We present a detailed experimental architecture for isolating the thermodynamic signature of quantum measurement record formation from the dominant dissipation of conventional readout chains. The differential microcalorimetry protocol employs matched ON/OFF branches that share identical premeasurement pulses, routing losses, and amplifier chains, differing only in whether an objective classical record is stabilized. The measurand is the per-shot differential energy ΔQ = Q_ON - Q_OFF. A thermal circuit model predicts the expected signal magnitude (~10^-4 zJ per bit at 10 mK), bandwidth requirements, and integration times needed to achieve statistical significance. We provide explicit calibration strategies, drift-correction methods, and a detection pipeline based on lock-in modulation. The architecture is designed for implementation in circuit quantum electrodynamics platforms using SNS nanobolometers or transition-edge sensors. This methods paper complements the theoretical prediction of a Landauer-scale heat bound for record formation and provides the engineering blueprint for its experimental verification.