Um, that's covered by an NDA--Non-Disclosure Agreement.
Those are generally QUITE enforceable, even in California and often last for 3 to 5 years.
Non-compete is quite different.
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.
Don't forget that not only do companies lose their "IP" with outgoing workers, but they also get more free with incoming ones. Perhaps it balances out but with a net positive effect since effective skills get spread around the industry instead of being locked up whereever they were discovered.
I think this is part of a bigger argument about how much IP protection is enough to encourage innovation but not so much that it stifles the market. You seem to be advocating protecting every last little bit of knowledge but perhaps that's stifling for the economy overall even if it is more fair for individual members.
Intellectual property is a bit of a misnomer it has very little in common with property of the standard sort and the burden falls upon you to explain why we ought to create greater artificial scarcity for imaginary property.
+ My point is nearly everything that you learn at a company could be considered a 'trade secret' - depending on the company or project.
In the example I gave, I listed a variety of situations in which minute operational skills and knowledge, all contribute to be 'key information' regarding the development of the product, and can essentially be 'trade secrets'.
Ergo - it would be nary difficult to work for a competitor and not give that information up.