时间：3月15日上午10:30

地点：近代物理系210会议室

报告人：Tim Byrnes, Assistant Professor, NYU Shanghai

报告题目：Quantum coherence and its distribution in multipartite systems

报告摘要：While quantum coherence is a concept that has been around since the dawn of quantum mechanics, quantifying it in a rigorous quantum information sense was only recently achieved.  We use a new coherence measure with entropic nature and metric properties, based on the quantum Jensen-Shannon divergence. In particular, it obeys a triangle inequality which allows for a general method of finding the distribution of coherence in multipartite systems. 

We find that there are trade-off relations between the various contributions of coherence, as a function of the parameters of the quantum state. In bipartite systems the coherence resides on individual sites or is distributed among the sites, which contribute in a complementary way. In more complex systems, the characteristics of the coherence can display more subtle changes with respect to the parameters of the quantum state. This allows us to define the shareability of coherence, leading to monogamy relations for coherence.  Applications of coherence to detect quantum phase transitions, and its time evolution will also be discussed. 

References

Radhakrishnan, Manikandan, Segar, TB, Phys. Rev. Lett. 116, 150504, (2016)

Radhakrishnan, Ermakov, TB Phys. Rev. A 96, 012341 (2017)

Radhakrishnan, Manikandan, Segar, TB Scientific Reports 7, 13865 (2017)