Weak value tomography of strong quantum measurements

Xuanmin Zhu, Dezheng Zhang, Runping Gao +3 more

Xuanmin Zhu, Yuanchun Deng, Runping Gao +3 more

Quantum state tomography strategy via weak value is valid for arbitrary dimensional systems, and can be easily realized. However, the efficiency of quantum state tomography strategy via weak value is lower than that of the conventional quantum state tomography (QST), especially for high-dimensional systems. To improve the efficiency of the scheme, we propose a two-step adaptive quantum state tomography via weak value for pure states (AQSTW). In AQSTW, by using appropriate measurement strength, the efficiency of AQSTW is significantly larger than that of the conventional QST, especially for high-dimensional systems. And AQSTW can be easily implemented. These results demonstrate AQSTW may be useful in the measurements of the unknown quantum states.

Yosep Kim, Yong‐Su Kim, Sang‐Yun Lee +4 more

We demonstrate measurement of the sequential weak value of two incompatible observables by making use of two-photon quantum interference. We also demonstrate direct quantum process tomography of a qubit channel using the sequential weak value.

Jeff S. Lundeen, Alejandro Feito, Hendrik B. Coldenstrodt-Ronge +6 more

Allen Lobo, Carlos Alberto de Lima Ribeiro

Yosep Kim, Yong-Su Kim, Sang‐Yun Lee +4 more

The weak value concept has enabled fundamental studies of quantum measurement and, recently, found potential applications in quantum and classical metrology. However, most weak value experiments reported to date do not require quantum mechanical descriptions, as they only exploit the classical wave nature of the physical systems. In this work, we demonstrate measurement of the sequential weak value of two incompatible observables by making use of two-photon quantum interference so that the results can only be explained quantum physically. We then demonstrate that the sequential weak value measurement can be used to perform direct quantum process tomography of a qubit channel. Our work not only demonstrates the quantum nature of weak values but also presents potential new applications of weak values in analyzing quantum channels and operations.