More Is Not Necessarily Easier

更容易随机化的门提供更准确的保真度估计

Easier randomizing gates provide more accurate fidelity estimation

本研究通过实验和理论分析，展示了使用单量子位泡利门进行随机化能有效减少系统误差，提高量子门保真度估计的准确性。

Are observables necessarily Hermitian?

Observables are believed that they must be Hermitian in quantum theory. Based on the obviously physical fact that only eigenstates of observable and its corresponding probabilities, i.e., spectrum distribution of observable are actually observed, we argue that observables need not necessarily to be Hermitian. More generally, observables should be reformulated as normal operators including Hermitian operators as a subclass. This reformulation is consistent with the quantum theory currently used and does not change any physical results. The Clauser-Horne-Shimony-Holt (CHSH) inequality is taken a…

量子信道区分中的纠缠：有时少即是多

Entanglement in quantum channel discrimination: sometimes less is more

研究纠缠在量子信道区分中的作用，发现过度纠缠会显著降低区分能力，并引入最大纠缠最坏情况（MEWC）和最佳情况（MEBC）信道对的概念。

Estimation of n non-identical unitary channels

We investigate the simultaneous estimation of $n$ not necessarily identical unitary channels using multi-partite entanglement. We examine whether it is possible for the rate at which the mean square error decreases to be greater than that using the channels individually. For a reasonably general situation, in which there is no functional dependence between the channels, we show that this is not possible. We look at a case in which the channels are not necessarily identical but depend on a common variable. In this case, the mean square error decreases more rapidly using multi-partite entangleme…

Testing the Everett Interpretation of Quantum Mechanics with Cosmology

In this brief note, we argue that contrarily to what is still often stated, the Everett many-worlds interpretation of quantum mechanics is not in principle impossible to test. It is actually not more difficult (but not easier either) to test than most other kinds of multiverse theories. We also remind why multiverse scenarios can be falsified.

Polarization of light and the spin state of photon

The comparison of the polarization and spin of light is presented in the paper. It is shown that it is more easier and clearer to use the polarization of the light to explain the effect of the interaction of light and atoms than that of spin of the light. The paper also gives rise to the question whether or not the concept of spin for photon have any essence for its existence.