1. Taking tomographic measurements for photonic qubits 88 ns before they are created*
- Author
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Guo-Yong Xiang, Chao Zhang, Chuan-Feng Li, Guang-Can Guo, Anthony Laing, Geoff J. Pryde, Han-Sen Zhong, Zhibo Hou, and Qi Yin
- Subjects
Physics ,Quantum Physics ,Process tomography ,Photon ,business.industry ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,Quantum channel ,021001 nanoscience & nanotechnology ,01 natural sciences ,Teleportation ,Computational physics ,Qubit ,0103 physical sciences ,Tomography ,Photonics ,Quantum Physics (quant-ph) ,010306 general physics ,0210 nano-technology ,business ,Quantum teleportation - Abstract
We experimentally demonstrate that tomographic measurements can be performed for states of qubits before they are prepared. A variant of the quantum teleportation protocol is used as a channel between two instants in time, allowing measurements for polarisation states of photons to be implemented 88 ns before they are created. Measurement data taken at the early time and later unscrambled according to the results of the protocol's Bell measurements, produces density matrices with an average fidelity of $0.90 \pm 0.01$ against the ideal states of photons created at the later time. Process tomography of the time-reverse quantum channel finds an average process fidelity of $0.84 \pm 0.02$. While our proof-of-principle implementation necessitates some post-selection, the general protocol is deterministic and requires no post-selection to sift desired states and reject a larger ensemble., Comments welcome
- Published
- 2021