Title
Quantum Capacity Bounds of Gaussian Thermal Loss Channels and Achievable Rates With Gottesman-Kitaev-Preskill Codes
Abstract
Gaussian thermal loss channels are of particular importance to quantum communication theory since they model realistic optical communication channels. Except for special cases, the quantum capacity of Gaussian thermal loss channels is not yet quantified completely. In this paper, we provide improved upper bounds of the Gaussian thermal loss channel capacity, both in energy-constrained and unconstrained scenarios. We briefly review Gottesman-Kitaev-Preskill (GKP) codes and discuss their experimental implementation. We then prove, in the energy-unconstrained case, that a family of GKP codes achieves the quantum capacity of Gaussian thermal loss channels up to at most a constant gap from the improved upper bound. In the energy-constrained case, we formulate a biconvex encoding and decoding optimization problem to maximize entanglement fidelity. Then, we solve the biconvex optimization heuristically by an alternating semi-definite programming method and report that, starting from Haar random initial codes, our numerical optimization yields a hexagonal GKP code as an optimal encoding in a practically relevant regime.
Year
DOI
Venue
2019
10.1109/TIT.2018.2873764
IEEE Transactions on Information Theory
Keywords
Field
DocType
Optical losses,Quantum mechanics,Upper bound,Channel capacity,Decoding,Encoding,Optimization
Discrete mathematics,Topology,Quantum entanglement,Computer science,Upper and lower bounds,Biconvex optimization,Gaussian,Quantum information science,Channel capacity,Optimization problem,Quantum capacity
Journal
Volume
Issue
ISSN
65
4
0018-9448
Citations 
PageRank 
References 
0
0.34
0
Authors
3
Name
Order
Citations
PageRank
Kyungjoo Noh100.34
Victor V. Albert200.34
Liang Jiang302.70