Quantum Key is the first album with music recorded after Edgar Froese had passed away in January 2015. Nevertheless the first three of the four tracks on this release are credited to Edgar Froese besides Thorsten Quaeschning and Ulrich Schnauss, and Edgar Froese is listed as performer as well. Hence it can be assumed that the new TD line-up was already working on these compositions when he unexpectedly died, or, at least, that these tracks are based on musical sketches he has left behind. While not credited as composer, Hoshiko Yamane performs violin on all four tracks.
The first composition, Genesis Of Precious Thoughts is mentioned as "Taken from the forthcoming album Quantum Gate", while the remaining tracks are exclusive for this cupdisc.
Announcements of this album prior to release featured a cover slightly different from the one finally used (see above).
A short time after its CD release this album became available as MP3 download at the Tangerine Dream Download Shop as well.
In November 2016 the album was released on vinyl.
CD: eastgate 075 CD; black/blue/white disc; matrix code: eastgate 075; cardboard sleeve; no order number on disc or sleeve
2016: Invisible Hands
LP: IH 69
2015: Tangerine Dream Download Shop
Download: ; complete release or individual tracks as MP3