Quantum measurements with post-selection

Antti P. Vepsäläinen

Art Hobson

Jeff Tollaksen, Debabrata Ghoshal

If operations in a quantum computer were conditioned on the results of a subsequent post-selection measurement, then NP-complete problems could be solved in polynomial time. Using the natural connection between post-selection and NP, we show that this result is un-physical by considering constraints on new kinds of measurements which depend on the future post-selection in a non-trivial way. We review practical quantum information advantages of post-selection.

Pierre Meystre

Yong-Li Wen, Shanchao Zhang, Hui Yan +1 more

Direct weak or strong measurement of quantum wave function based on post-selections has been widely explored; however, the efficiency of the measurement is heavily limited by the success probability of post-selection. Here we propose a modified scheme to directly measure photon–s wave function by simply inserting a liquid crystal plate before the post-selection stage. Numerical simulations demonstrate that our modified method can significantly increase the efficiency of post selection. Our proposal would speed up the quantum wave function measurement with high resolution and high fidelity.