Taking tomographic measurements for photonic qubits 88 ns before they are created*

We experimentally demonstrate that tomographic measurements can be performed for states of qubits before they are prepared. A variant the quantum teleportation protocol is used as a channel between two instants in time, allowing polarization photons to implemented 88 ns created. Measurement data taken at early time and later unscrambled according results protocol’s Bell measurements, produces density matrices with an average fidelity 0.90±0.01 against ideal created time. Process tomography reverse finds process 0.84±0.02. While our proof-of-principle implementation necessitates some post-selection, general deterministic requires no post-selection sift desired reject larger ensemble.