Reversible entanglement beyond quantum operations
Yu-Ao Chen, Xin Wang, Lei Zhang, Chenghong Zhu · Physical Review Research · 2025
We introduce a reversible theory of exact entanglement manipulation by establishing a necessary and sufficient condition for state transfer under trace-preserving transformations that completely preserve the positivity of partial transpose (PPT). Under these free transformations, we show that logarithmic negativity emerges as the pivotal entanglement measure for determining entangled states' transformations, analogous to the role of entropy in the second law of thermodynamics. Previous results proved that entanglement is irreversible under quantum operations that completely preserve PPT and under all nonentangling transformations. In this work, we find that going beyond the complete positivity constraint imposed by standard quantum mechanics enables a reversible theory of exact entanglement manipulation, which may suggest a potential incompatibility between the reversibility of entanglement and the fundamental principles of quantum mechanics.