Super fidelity and related metrics

Open Physics ◽  
2011 ◽  
Vol 9 (4) ◽  
Author(s):  
Zhi-Hua Chen ◽  
Zhihao Ma ◽  
Fu-Lin Zhang ◽  
Jing-Ling Chen
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Quantum States

AbstractWe report a new metric of quantum states. This metric is built up from super-fidelity, which has a deep connection with the Uhlmann-Jozsa fidelity and plays an important role in quantum information processing. We find that the new metric possesses some interesting properties.

Proposal for dimensionality testing in QPQ

2018 ◽  
Vol 18 (13&14) ◽  
pp. 1125-1142
Author(s):  
Arpita Maitra ◽  
Bibhas Adhikari ◽  
Satyabrata Adhikari
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum System ◽  
Quantum State ◽  
Quantum Information Processing ◽  
Quantum States ◽  
Quantum Private Query ◽  
Unfair Advantage ◽  
Security Proofs

Recently, dimensionality testing of a quantum state has received extensive attention (Ac{\'i}n et al. Phys. Rev. Letts. 2006, Scarani et al. Phys. Rev. Letts. 2006). Security proofs of existing quantum information processing protocols rely on the assumption about the dimension of quantum states in which logical bits are encoded. However, removing such assumption may cause security loophole. In the present paper, we show that this is indeed the case. We choose two players' quantum private query protocol by Yang et al. (Quant. Inf. Process. 2014) as an example and show how one player can gain an unfair advantage by changing the dimension of subsystem of a shared quantum system. To resist such attack we propose dimensionality testing in a different way. Our proposal is based on CHSH like game. As we exploit CHSH like game, it can be used to test if the states are product states for which the protocol becomes completely vulnerable.

scholarly journals Coherent preorder of quantum states

2020 ◽  
Vol 20 (13&14) ◽  
pp. 1124-1137
Author(s):  
Zhaofang Bai ◽  
Shuanping Shuanping Du
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Coherent States ◽  
Quantum Coherence ◽  
Quantum Information Processing ◽  
Quantum States ◽  
Mixed States ◽  
Quantum Hypothesis ◽  
Quantum Hypothesis Testing

As an important quantum resource, quantum coherence play key role in quantum information processing. It is often concerned with manipulation of families of quantum states rather than individual states in isolation. Given two pairs of coherent states $(\rho_1,\rho_2)$ and $(\sigma_1,\sigma_2)$, we are aimed to study how can we determine if there exists a strictly incoherent operation $\Phi$ such that $\Phi(\rho_i) =\sigma_i,i = 1,2$. This is also a classic question in quantum hypothesis testing. In this note, structural characterization of coherent preorder under strongly incoherent operations is provided. Basing on the characterization, we propose an approach to realize coherence distillation from rank-two mixed coherent states to $q$-level maximally coherent states. In addition, one scheme of coherence manipulation between rank-two mixed states is also presented.

scholarly journals “Quantumness” versus “classicality” of quantum states and quantum protocols

2018 ◽  
Vol 16 (02) ◽  
pp. 1850014
Author(s):  
Aharon Brodutch ◽  
Berry Groisman ◽  
Dan Kenigsberg ◽  
Tal Mor
Keyword(s):  
Quantum Mechanics ◽  
Information Processing ◽  
Quantum Information ◽  
Quantum State ◽  
Quantum Information Processing ◽  
Quantum States ◽  
Separable States ◽  
Quantum Properties ◽  
Quantum Protocols

Entanglement is one of the pillars of quantum mechanics and quantum information processing, and as a result, the quantumness of nonentangled states has typically been overlooked and unrecognized until the last decade. We give a robust definition for the classicality versus quantumness of a single multipartite quantum state, a set of states, and a protocol using quantum states. We show a variety of nonentangled (separable) states that exhibit interesting quantum properties, and we explore the “zoo” of separable states; several interesting subclasses are defined based on the diagonalizing bases of the states, and their nonclassical behavior is investigated.

Quantum Information Processing

2001 ◽  
Author(s):  
David P. DiVincenzo ◽  
Charles H. Bennett
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing
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