Brent at Evergreen Gardenworks describes them this way.
http://evergreengardenworks.com/prunus.htm
"Punica granatum 'Emperor' This little plant was brought from Japan by Don Herzog of the Miniature Plant Kingdom and is perhaps the finest dwarf pomegranate available today. It grows very slowly into a very twiggy flattened dome about 3 feet x 4 feet and has good red orange single flowers followed by the most beautiful deep mahogany-purple skinned 1 1/2 inch plus fruits. It appears to be quite cold hardy, tests so far show that it will survive to 18ø with little damage and will probably survive to 10ø with the minimal protection of Reemay or other spun row cover. Excellent for bonsai."
Unfortunately, he has a waiting list for starters right now.