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キーワード:
QUANTUM KEY DISTRIBUTION; MANY-BODY SYSTEMS; UNCERTAINTY PRINCIPLE;
JOINT MEASUREMENT; OPTICAL HOMODYNE; EXCESS-NOISE; INFORMATION; PHASE;
OBSERVABLES; VARIABLESOptics; Physics;
要旨:
We examine the moment-reconstruction performance of both the homodyne and heterodyne (doublehomodyne) measurement schemes for arbitrary quantum states and introduce moment estimators that optimize the respective schemes for any given data. In the large-data limit, these estimators are as efficient as the maximum-likelihood estimators. We then illustrate the superiority of the heterodyne measurement for the reconstruction of the first and second moments by analyzing Gaussian states and many other significant nonclassical states. Finally, we present an extension of our theories to two-mode sources, which can be straightforwardly generalized to all other multimode sources.
