A Unified Quantum Interferometric Framework for Interaction-Free Measurement and Delayed-Choice Experiments

How can the distinct phenomena of interaction-free measurement (IFM) and delayed-choice (DC) experiments be reconciled within a single, unified quantum interferometric framework? The authors seek to demonstrate that both paradigms share a common operational origin by modeling them as a coherent quantum circuit.

The researchers utilize a four-qubit quantum circuit based on the Mach-Zehnder interferometer (MZI) architecture. The framework employs an ancillary qubit to control the interaction between a photon and a quantum bomb, and another ancillary qubit to act as a quantum switch for the second beam splitter. By applying controlled quantum gates (specifically CCN and CCH gates), the system evolves in a superposition of interaction and non-interaction regimes. This allows the researchers to continuously interpolate between IFM and DC behaviors by adjusting control parameters.

The study demonstrates that the proposed circuit successfully replicates both IFM and DC phenomena. By adjusting the control parameter for the second beam splitter, the system exhibits a continuous transition from particle-like behavior (where which-path information is preserved) to wave-like behavior (where interference patterns emerge). The framework is validated through numerical simulations using Qiskit, the Qniverse platform, and execution on IBM quantum hardware, showing that the theoretical predictions hold even in the presence of realistic hardware imperfections.

This work provides a unified perspective on foundational quantum concepts that are typically studied in isolation. By representing these phenomena within a single quantum circuit, the authors offer a clearer understanding of how complementarity and counterfactual information extraction emerge from the same underlying unitary evolution. This approach could inform future designs for quantum information processing and communication protocols.