Entangled-coherent-state quantum key distribution with entanglement witnessing

David S. Simon,1,2 Gregg Jaeger,2,3 and Alexander V. Sergienko2,4,5 1Department of Physics and Astronomy, Stonehill College, 320 Washington Street, Easton, Massachusetts 02357, USA 2Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary’s Street, Boston, Massachusetts 02215, USA 3Division of Natural Sciences and Mathematics, Boston University, Boston, Massachusetts 02215, USA 4Photonics Center, Boston University, 8 Saint Mary’s Street, Boston, Massachusetts 02215, USA 5Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA (Received 23 May 2013; revised manuscript received 15 September 2013; published 15 January 2014)