Quality of correlation in quantum information

崔景云, 曾天海, 娄乐生

A strong and stable correlation in quantum information is of high quality for quantum information processing.We define two quantities,selective average correlation and ripple coefficient,to evaluate the quality of correlation in quantum information in a time interval.As a new communication channel,Heisenberg spin chains are widely investigated.We select a two-qubit Heisenberg XXZs pin chain with Dzyaloshinskii-Moriya interaction in an inhomogeneous magnetic field as an example,and use the two quantities to evaluate the qualities of the correlation in quantum information with different measures.The result shows that,if the time evolutions are similar,there needs only evaluating one of them to know when the correlation has high quality for quantum information processing.

Simon J. D. Phoenix, Stephen Mark Barnett

Matthew Otten, Keshav Kapoor, A. Barış Özgüler +4 more

As larger, higher-quality quantum devices are built and demonstrated in quantum information applications, such as quantum computation and quantum communication, the need for high-quality quantum memories to store quantum states becomes ever more pressing. Future quantum devices likely will use a variety of physical hardware, some being used primarily for processing of quantum information and others for storage. Here we study the correlation of the structure of quantum information with physical noise models of various possible quantum memory implementations. Through numerical simulation of different noise models and approximate analytical formulas applied to a variety of interesting quantum states, we provide comparisons between quantum hardware with different structure, including both qubit- and qudit-based quantum memories. Our findings point to simple, experimentally relevant formulas for the relative lifetimes of quantum information in different quantum memories and have relevance to the design of hybrid quantum devices.

Masashi Ban

Luis Roa-Oppliger

Qiang Zhou, Wei Zhang, Yidong Huang +1 more

Single photons are essential resource for quantum communication and quantum information processing, which can carry quantum information to distant locations. A promising scheme for single photon generation is the heralded single photon source (HSPS), which is based on the generation of correlated photon pairs (CPPs). Utilizing the quantum correlation property of the CPPs, one photon of the CPP is detected providing an electrical signal to herald the other photon as a single photon output. Recently, 1.5 μm CPP generation through spontaneously four wave-mixing (SFWM) in fiber has focused much attention, which provides a practical way to realize 1.5 μm fiber-based HSPS. The quality of a HSPS is described by the preparation efficiency and g(2)(0). In the fiber-based HSPS, the preparation efficiency is determined by the loss of the filtering and splitting system and the noise photons generated by spontaneously Raman scattering (SpRS). Considering the impact of the SpRS can be reduced by cooling the fiber and optimizing the frequency detuning of filtering and splitting system, the loss of the filtering and splitting system may give a theoretical up-limit of the preparation efficiency. In this paper, using commercial fiber components, we realize a high quality HSPS based on cooled fiber with a preparation efficiency of 80% under a g(2)(0) of0.06, showing its great potential in the application of quantum information technology.