Your comments about NDA's are not quite right. NDA's do not capture a lot of the essential issue.
Pragmatically speaking, it's nary impossible to work in some fields, and then move to a competing firm without passing on know how or trade secrets.
Even the 'manner of approach' to a problem, while it may not be a trade secret, is basically a core part of the 'true IP' that is developed by a company.
Using DWAVE as an example - there are thousands of 'little things' that they will have had to figure out along the way - from which parts to use, which vendors work well, material types, tooling, physical test units, support gear (like cooling etc.) - all of this is IP.
Any number of small issues can be the 'key ingredients' that make or break a project. When DWAVE spends a year trying to figure out how to keep some material at a steady temperature in order to bind it to another ... then that's IP.
It's a paradox when nearly one's entire skill set is tantamount to 'trade secrets' but it's feasible.
An NDA - in the broadest sense - in this case would be a de-facto 'non compete' - because there's hardly a thing this Eng could do for Google that wouldn't involve giving away important information.
In case you guys are not aware: hiring people to steal away trade secrets and know-how is very common in the Valley, often by major players and firms.
If you haven't noticed - the biggest and most successful tech companies all have either natural monopolies (i.e. Facebook/Twitter with network externalities), or insurmountable massive barriers to entry keeping others out (i.e. Apple having MacOS/iOS, a retail distribution chain, massive leverage over supply chain, and market share).
In business scenarios it happens as well, in less 'protectable' scenarios. Apple snared away tons of BlackBerry sales/BD execs - not because they were necessarily skilled or talented - but because of their established relationships within carrier channels. Apple was buying access to Verizon and AT&T - not random sales guys abilities.