2-MODE QUANTUM-OPTICAL STATE MEASUREMENT - SAMPLING THE JOINT DENSITY-MATRIX

We propose schemes for measuring the joint quantum state of a two-mode optical field using balanced homodyne detection, thereby generalizing earlier single-mode schemes. We distinguish between two cases-the cas e where the two modes are spatially separable and the case where they are nonseparable. For each case we present a generalization of the dir ect sampling method of state reconstruction and point out that its adv antages over inverse Radon methods are even greater here than in the s ingle-mode case. In the case of two modes that cannot be separated we propose a scheme in which a single balanced homodyne detector is used for data collection.