Multivariate Discrimination in Quantum Target Detection

Optimal quantum discrimination of single-qubit unitary gates between two candidates

We analyze a discrimination problem of a single-qubit unitary gate with two candidates, where the candidates are not provided with their classical description, but their quantum sample is. More precisely, there are three unitary quantum gates -- one target and one sample for each of the two candidates -- whose classical description is unknown except for their dimension. The target gate is chosen equally among the candidates. We obtain the optimal protocol that maximizes the expected success probability, assuming the Haar distribution for the candidates. This problem is originally introduced in…

面向多变量蒙特卡洛模拟的高效量子态制备

Efficient state preparation for multivariate Monte Carlo simulation

针对多变量量子态制备现有方法门数量随变量数指数增长的问题，提出基于多变量量子信号处理（M-QSP）的量子算法，将门数量降至线性，可高效支撑金融等领域的多变量蒙特卡洛模拟。

纠缠辅助非局域正交态集的鉴别

Entanglement-Assisted Discrimination of Nonlocal Sets of Orthogonal States

本文研究了多粒子纠缠在非局域正交态集鉴别中的作用，提出高效的LOCC协议，探讨了不同纠缠辅助方案的资源消耗，并发现避免量子 teleportation 的协议通常更高效。

Entanglement-enhanced testing of multiple quantum hypotheses

Quantum hypothesis testing has been greatly advanced for the binary discrimination of two states, or two channels. In this setting, we already know that quantum entanglement can be used to enhance the discrimination of two bosonic channels. Here, we remove the restriction of binary hypotheses and show that entangled photons can remarkably boost the discrimination of multiple bosonic channels. More precisely, we formulate a general problem of channel-position finding where the goal is to determine the position of a target channel among many background channels. We prove that, using entangled ph…

Any four orthogonal ququad-ququad maximally entangled states are locally markable

In quantum state discrimination, the observers are given a quantum system and aim to verify its state from the two or more possible target states. In the local quantum state marking as an extension of quantum state discrimination, there are N composite quantum systems and N possible orthogonal target quantum states. Distant Alice and Bob are asked to correctly mark the states of the given quantum systems via local operations and classical communication. Here we investigate the local state marking with N 4 ${\otimes}$ 4 systems, N=4, 5, 6, and 7. Therein, Alice and Bob allow for three local ope…

Ultimate limits for multiple quantum channel discrimination

Quantum hypothesis testing is a central task in the entire field of quantum information theory. Understanding its ultimate limits will give insight into a wide range of quantum protocols and applications, from sensing to communication. Although the limits of hypothesis testing between quantum states have been completely clarified by the pioneering works of Helstrom in the 70s, the more difficult problem of hypothesis testing with quantum channels, i.e., channel discrimination, is less understood. This is mainly due to the complications coming from the use of input entanglement and the possibil…