TCMS seminar

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Lecture Title	"Entanglement-assisted weak measurement and Heisenberg-limited precision"
Date	Tuesday 10 February 2015 15:00
Lecturer	Shengshi Pang （University of South California, Posdoc）
Place	South-Lab. Building　Room 408
Summary	Large weak value amplification (WVA) has been of great interest for its potential in enhancing the sensitivity of measuring small physical parameters. However, a major shortcoming of WVA is the low utility of physical resources due to the postselection on the system. This has also led to the recent heated debate on the advantage of WVA in quantum metrology. In this research, we studied optimizing the choice of postselected state to maximize the postselection probability for a given weak value. It is found that entanglement between the initial systems can significantly reduce the resources discarded by postselection, and as a consequence increase the Fisher information of weak measurement. Based on this, we proposed an improved protocol of weak measurement assisted by entanglement. A remarkable result with this new protocol is that the loss of Fisher information by postselection can be reduced to as low as the order of the parameter, which is usually negligible in weak measurements, and the precision of the measurement can be enhanced to the well-known Heisenberg limit. To illustrate how to realize this protocol, some simple quantum circuits are provided for implementing it with qubits.
Contact	Yutaka Shikano

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