Quantum 2025 – scientific programme
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MON: Monday Contributed Sessions
MON 17: Quantum Communication and Networks: Theory
MON 17.2: Talk
Monday, September 8, 2025, 16:45–17:00, ZHG010
No-Go Theorem for Generic Simulation of Qubit Channels with Finite Classical Resources — •Sahil Gopalkrishna Naik1, Nicolas Gisin2,3,4, and Manik Banik1 — 1S. N. Bose National Center for Basic Sciences, Kolkata, India — 2University of Geneva, 1211 Geneva 4, Switzerland. — 3Constructor University, Bremen, Germany. — 4Constructor Institute of Technology, Geneva, Switzerland.
The mathematical framework of quantum theory, though fundamentally distinct from classical physics, raises the question of whether quantum processes can be efficiently simulated using classical resources. For instance, a sender (Alice) possessing the classical description of a qubit state can simulate the action of a qubit channel through finite classical communication with a receiver (Bob), enabling Bob to reproduce measurement statistics for any observable on the state. Here, we contend that a more general simulation requires reproducing statistics of joint measurements, potentially involving entangled effects, on Alice's system and an additional system held by Bob. We establish a no-go result, demonstrating that such a general simulation for the perfect qubit channel is impossible with finite classical communication. Furthermore, we show that entangled effects render classical simulation significantly more challenging compared to unentangled effects. On the other hand, for noisy qubit channels with depolarizing noise, we demonstrate that general simulation is achievable with finite communication. Notably, the required communication increases as the noise decreases, revealing that large classical resources are necessary for its classical simulation.
Keywords: Classical Simulation; Simulation of Quantum Resources; Quantum Communication; Prepare Measure Scenario; Random Access Codes