High Throughput Global Entropy Source Is there an entropy source that provides the following three properties?


true randomness
for a distinct time-period, produces same (random) data on two devices that are less than 10 km apart from each other
high throughput, so recording randomness for a few minutes requires terabytes of data storage


I considered sources like atmospheric noise or similar, but I am unsure whether they fulfill property (2) (and (3))...
I am going to assume that you're a regular Joe (no offence), and not a rocket scientist or millionaire philanthropist with a huge research budget, as this determines the answer.

No.

There is no true random number generator available to you that can meet all of your three tests.  By your mention of atmospheric noise, I'm further assuming that you're meaning a true random number generator based on physicalities, rather than a pseudo random number generator like the Mersenne Twister.

Specifically:


Yes.  True randomness and entropy are all around you.  I mean  sources of unpredictability.  The noise on your camera phone party pics, the jitter in your PC's system clock or noise on a voltage regulator valve.  These will not though produce uniformly random numbers without some randomness extraction.
Yes.  Any of the above will achieve this.  There is no interaction between the examples I've given.  (Even photon entanglement can be mitigated over a metre's distance but you won't be building one of those).
No.  Another assumption is you want a rate of 5 TB in 5 minutes.  That's >100 Mbits /s.  You cannot achieve this as Joe.  Unless you spend a great deal and are pretty clever building stuff.  I'm not aware of any simple devices like ring oscillators that can easily output this rate at the hobby level of construction.  (I exclude Intel CPUs as those are highly suspect undefined generators probably crippled by the NSA.)


3 1/2.  Be very careful with atmospheric noise.  I don't believe that it's possible for typical hobbyists to generate more than a few bits /s from this as the safety margin for true randomness will be enormous. The EM spectrum is full so your only course is to build a very broadband receiver and rely on the central limit theorem to achieve randomness. You can't use a tranny radio.  You will just end up sampling thermal noise on your receiving circuitry, oscillations of the phase locked loop FM detector or Lady Gaga's latest hit.  That probably happens at random.org and they just side step it with technobabble so don't be encouraged by their example.  Tip:  Use a 24V Zener diode. Enough true randomness for Joes.

Can I suggest that you see this question regarding your property 3?