Quantum Learnability is Arbitrarily Distillable

Quantum key distribution based on arbitrarily-weak distillable entangled states

States with private correlations but little or no distillable entanglement were recently reported. Here, we consider the secure distribution of such states, i.e., the situation when an adversary gives two parties such states and they have to verify privacy. We present a protocol which enables the parties to extract from such untrusted states an arbitrarily long and secure key, even though the amount of distillable entanglement of the untrusted states can be arbitrarily small.

Maximally-Disordered Distillable Quantum States

We explore classical to quantum transition of correlations by studying the quantum states located just outside of the classically-correlated-states-only neighborhood of the maximally mixed state (the largest separable ball (LSB)). We show that a natural candidate for such states raises the possibility of a layered transition, i.e., an annular region comprising only classical and the classical-like bound entangled states, followed by free or distillable entanglement. Surprisingly, we find the transition to be abrupt for bipartite systems: distillable states emerge arbitrarily close to the LSB. …

Quantum states for perfectly secure secret sharing

In this work, we investigate what kinds of quantum states are feasible to perform perfectly secure secret sharing, and present its necessary and sufficient conditions. We also show that the states are bipartite distillable for all bipartite splits, and hence the states could be distillable into the Greenberger-Horne-Zeilinger state. We finally exhibit a class of secret-sharing states, which have an arbitrarily small amount of bipartite distillable entanglement for a certain split.

Extrapolated Quantum States, Void States, and a Huge Novel Class of Distillable Entangled States

A nice and interesting property of any pure tensor-product state is that each such state has distillable entangled states at an arbitrarily small distance $ε$ in its neighborhood. We say that such nearby states are $ε$-entangled, and we call the tensor product state in that case, a "boundary separable state", as there is entanglement at any distance from this "boundary". Here we find a huge class of separable states that also share that property mentioned above -- they all have $ε$-entangled states at any small distance in their neighborhood. Furthermore, the entanglement they have is proven t…

连续变量量子核机器学习

Quantum Kernel Machine Learning With Continuous Variables

本文提出连续变量量子核的闭式表示，推导其一般解并量化量子-经典分离，证明无限恒星秩核可被有限秩近似，并模拟显示恒星秩与带宽影响学习性能。