Analysis of errors in an optical Controlled-NOT gate with a high-precision testing bed

In our paper, we report the analysis of errors in the C-NOT gate using a high-precision test-bed. From the result of previous experiment, we have identified two main causes of errors: one is the mismatch between optical modes, and the other is the un-intentional phase shift between two polarization, horizontal polarizations and vertical polarization. To evaluate these factors more precisely, we construct a test-bed setup in which piezo-electric stages are used to avoid mode mismatch, and the extinction ratio of polarization is kept below 10^-3. In the poster, we will report the experimental results with the test-bed and the analysis of errors in detail.