Quantifying Quantum-Mechanical Processes

TL;DR

This paper introduces a universal framework for quantifying quantum-mechanical processes by distinguishing them from classical mimicry, applicable across various quantum phenomena and revealing new types of correlations.

Contribution

It presents a novel, general formalism for quantifying quantum processes that does not rely on specific states, enabling the identification of unique quantum correlations.

Findings

Successfully applied to fundamental quantum processes

Revealed new classes of quantum correlations

Framework applicable to diverse quantum systems

Abstract

The act of describing how a physical process changes a system is the basis for understanding observed phenomena. For quantum-mechanical processes in particular, the affect of processes on quantum states profoundly advances our knowledge of the natural world, from understanding counter-intuitive concepts to the development of wholly quantum-mechanical technology. Here, we show that quantum-mechanical processes can be quantified using a generic classical-process model through which any classical strategies of mimicry can be ruled out. We demonstrate the success of this formalism using fundamental processes postulated in quantum mechanics, the dynamics of open quantum systems, quantum-information processing, the fusion of entangled photon pairs, and the energy transfer in a photosynthetic pigment-protein complex. Since our framework does not depend on any specifics of the states being processed, it reveals a new class of correlations in the hierarchy between entanglement and Einstein-Podolsky-Rosen steering and paves the way for the elaboration of a generic method for quantifying physical processes.