Information characteristics of quantum Gaussian measurement channels

In a series of works devoted to multimode Gaussian measurement channels, the fundamental property of the "Gaussian maximizer" is established, on the basis of which the most important information characteristics of such channels are calculated. In [1], the achievable information is obtained for a gauge-invariant Gaussian ensemble of states, which closed the question posed in the early 1970s. In [2], the classical bandwidth of a channel satisfying the "threshold condition" that covers the gauge-invariant case is calculated. In [3], the entropy reduction was found and based on it, the entanglement-assisted capacity for a general-type quantum Gaussian measurement channel was determined.

References

1. Alexander S. Holevo, “Gaussian maximizers for quantum Gaussian observables and ensembles”, IEEE Transactions on Information Theory, 66:9 (2020), 5634-5641    
2. A. S. Holevo, A. A. Kuznetsova, “Information capacity of continuous variable measurement channel”, J. Phys. A: Math. Theor., 53:17 (2020), 175304, 13 pp.    
3. A. S. Holevo, A. A. Kuznetsova, “The information capacity of entanglement-assisted continuous variable quantum measurement”, J. Phys. A: Math. Theor., 53:37 (2020), 375307, 17 pp.    

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