An upper bound on the second order asymptotic expansion for the quantum communication cost of state redistribution

Quantum Conditional Mutual Information, Reconstructed States, and State Redistribution

We give two strengthenings of an inequality for the quantum conditional mutual information of a tripartite quantum state recently proved by Fawzi and Renner, connecting it with the ability to reconstruct the state from its bipartite reductions. Namely we show that the conditional mutual information is an upper bound on the regularised relative entropy distance between the quantum state and its reconstructed version. It is also an upper bound for the measured relative entropy distance of the state to its reconstructed version. The main ingredient of the proof is the fact that the conditional mu…

膨胀宇宙中高斯态的量子失谐

Quantum discord of Ganssian states in an expanding universe

该研究探究膨胀宇宙中连续变量量子失谐的再分配，发现其对膨胀率更敏感，不同模式对的诱导失谐程度有差异，还指出低动量最优质量粒子利于提取宇宙信息，丰富了相关理论框架。

Smooth Entropy Bounds on One-Shot Quantum State Redistribution

In quantum state redistribution as introduced in [Luo and Devetak (2009)] and [Devetak and Yard (2008)], there are four systems of interest: the $A$ system held by Alice, the $B$ system held by Bob, the $C$ system that is to be transmitted from Alice to Bob, and the $R$ system that holds a purification of the state in the $ABC$ registers. We give upper and lower bounds on the amount of quantum communication and entanglement required to perform the task of quantum state redistribution in a one-shot setting. Our bounds are in terms of the smooth conditional min- and max-entropy, and the smooth m…

基于数字分割算法的量子互信息重分配

Quantum mutual information redistribution by Number Partitioning algorithm

本文研究三方纯态中两体酉变换对量子互信息的重分配问题，证明互熵上界为2S(ρ_C)及其可实现条件，并提出一种基于改进数字分割问题的快速数值算法，用于高维情形下近似最大化量子互信息。

A one-shot achievability result for quantum state redistribution

We study the problem of entanglement-assisted quantum state redistribution in the one-shot setting and provide a new achievability result on the quantum communication required. Our bounds are in terms of the max-relative entropy and the hypothesis testing relative entropy. We use the techniques of convex split and position-based decoding to arrive at our result. We show that our result is upper bounded by the result obtained in Berta, Christandl, Touchette (2016).

Robust Randomness Amplifiers: Upper and Lower Bounds

A recent sequence of works, initially motivated by the study of the nonlocal properties of entanglement, demonstrate that a source of information-theoretically certified randomness can be constructed based only on two simple assumptions: the prior existence of a short random seed and the ability to ensure that two black-box devices do not communicate (i.e. are non-signaling). We call protocols achieving such certified amplification of a short random seed randomness amplifiers. We introduce a simple framework in which we initiate the systematic study of the possibilities and limitations of rand…