These clocks depend dilute gasses of atoms. Usually the process for preparing and probing the atoms takes at least a few hundred milliseconds, and usually in the seconds range. There's a bunch of reasons for this, probably two main reasons IMO:
1. Generally for precision clocks you need "cold" or "ultracold" atoms (essentially random doppler shifts of hot atoms kill your accuracy). This means something like microkelvins - this is hard to prepare quickly. And atoms are constantly lost/heated due to collisions with stray gas molecules, even though the pressure is usually something like a quadrillion times lower than atmosphere. There's research into continuous ultracold atom sources, and you could prepare way more than you need and siphon a few off at a time, but both are technically challenging.
2. The way these clocks work is essentially you have some laser, and an atom that only reacts to laser light of a very specific frequency. If the laser frequency is off from the exact frequency you can tell. A variety of effects means that the measurement process takes some time. It's like trying to accurately measure your heart rate in 1s vs 10s - a lot easier to do in the latter case.
Nothing fundamental, just technically quite painful.
Just judging by the torque specs and comparing to a nema23 stepper, seems like it needs an order of magnitude more torque to compare. Note that in the comparison chart they compare to a nema11, which is tiny compared to the steppers used in most hobby cncs.
Well it depends on what your bar is for a monopoly. E.g. I can only use Comcast where I live. Comcast is not technically a monopoly - I could move somewhere else where other providers are available. But the friction to change is high enough that they effectively are a monopoly to me.
No company is a monopoly if you are flexible enough. Where antitrust starts to become relevant is a bit of an arbitrary line. If you think "mobile phones" is the industry then Apple does not have a monopoly. But there are many people who would put up with a lot before switching from iOS to Android, because of apps, iCloud, iMessaging, or whatever.
Definitely not a cubic function though, you can't get a polynomial to hit 0 that nicely. Any polynomial's leading order term will dominate as x increases. Unless they're using a super high order polynomial and hiding the blowup off the edge of the plot.
1. Generally for precision clocks you need "cold" or "ultracold" atoms (essentially random doppler shifts of hot atoms kill your accuracy). This means something like microkelvins - this is hard to prepare quickly. And atoms are constantly lost/heated due to collisions with stray gas molecules, even though the pressure is usually something like a quadrillion times lower than atmosphere. There's research into continuous ultracold atom sources, and you could prepare way more than you need and siphon a few off at a time, but both are technically challenging.
2. The way these clocks work is essentially you have some laser, and an atom that only reacts to laser light of a very specific frequency. If the laser frequency is off from the exact frequency you can tell. A variety of effects means that the measurement process takes some time. It's like trying to accurately measure your heart rate in 1s vs 10s - a lot easier to do in the latter case.
Nothing fundamental, just technically quite painful.