Hi,
As I know, there is no open source one. But I really suggest trying this popular application JaM.
I think the industry standard would be our/Go2Group's JaM plugin. You can see the product here, as well as a partial list of our JaM customers at the bottom of this page: http://www.go2group.com/en/products/go2group-jam-plugin/
JaM costs $3,000 for unlimited users.
You can see more information on JaM at https://marketplace.atlassian.com/plugins/com.atlassian.jira.plugin.customfield.crm
We offer free evaluations and remote installation consulting via our ticket system and also by live web meetings from our engineering staff.
We also have a new integration platform, ConnectALL, which can integrate many to many ALM tools, including JIRA and Quality Center (as well as DOORS, TFS, ClearQuest etc). For more information, see http://www.go2group.com/en/products/go2group-connectall/