Tomography of a multimode quantum black box

作者：Fedorov Ilya A^*; Fedorov Aleksey K; Kurochkin Yury V; Lvovsky A I

来源：New Journal of Physics, 2015, 17(4): 043063.

DOI：10.1088/1367-2630/17/4/043063

• quantum process
• multimode
• black box
• beamsplitter
• tomography

We report a technique for experimental characterization of an M-mode quantum optical process, generalizing the single-mode coherent-state quantum-process tomography method [1, 2]. By measuring the effect of the process on multi-mode coherent states via balanced homodyne tomography, we obtain the process tensor in the Fock basis. This rank-4M tensor, which predicts the effect of the process on an arbitrary density matrix, is iteratively reconstructed directly from the experimental data via the maximum-likelihood method. We demonstrate the capabilities of our method using the example of a beam splitter, reconstructing its process tensor within the subspace spanned by the first three Fock states. In spite of using purely classical probe states, we recover quantum properties of this optical element, in particular the Hong-Ou-Mandel effect.

• 出版日期2015-4-29