gji

7 ms·

1.
by gji 5y ago
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 rea
2.
by gji 6y ago
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
3.
by gji 6y ago
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
4.
by gji 6y ago
You seem to be very convinced of this. At my institution, research activities has resumed for the past month (albeit with restrictions on occupancy).
5.
by gji 6y ago
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 blow
6.
by gji 6y ago
I'm a physics grad student finishing up a PhD, would you have some time/be willing to chat about industry jobs? Email is in bio.
7.
by gji 7y ago
Practical from a cultural standpoint or in terms of quantity? IIRC, people are required to wear masks when entering businesses in China now.
8.
by gji 7y ago
Those benefits only apply to people who work at companies that have less than 500 employees. Unfortunately, that leaves most people in the lurch. https://www.nytimes.com/2020/03/14/opinion/coronavirus-pel
9.
by gji 7y ago
I've been using this cable: https://www.amazon.com/dp/B074W1G389/ref=cm_sw_r_cp_awdb_t1_... Haven't used it for 100W charging so I don't know if it stands up to the full rated 5A though.
10.
by gji 7y ago
Interestingly, the 100m record difference is about 10%, which is roughly the same as the gap in the ultramarathon records (and in the record mile time). So the difference is fairly consistent across distances.
11.
by gji 7y ago
I'm pretty sure the way analog degrees are freedom are mapped onto symbols is very important. In principle, if you have infinite SNR over a limited bandwidth, you can have infinite rate of data transfer - e.g. if you can have infinitel
12.
by gji 8y ago
Source for this? I personally need 9+ hours as well but am constantly told I sleep for too long.
13.
by gji 8y ago
If you’re talking about the i9-9900, it’s a very high clock frequency part with “only” 8 cores and part of the consumer line (no ecc support). I’d actually think most people who have it run Windows and use it for things like gaming.
14.
by gji 8y ago
Nature letter here: https://www.nature.com/articles/s41586-018-0707-9 Looks like they developed advancements with lightweight high-voltage converters and performance of the thrusters.
15.
by gji 9y ago
I used to work on trapped ion experiments, and the limitation of the atom size was always the diffraction limit, which is limited by the NA of the lens (f-stop in camera terms) and the wavelength of light. In this case, the optical system (
16.
by gji 9y ago
Your first statement isn't quite true. See, for example, https://www.scottaaronson.com/blog/?p=473 In short, it's hard to classically model pretty simple quantum mechanical systems and sample the probability
17.
by gji 9y ago
Those numbers aren't that bad, actually. A cell phone's peak power draw isn't much more than 5W, so you'd need 10g / efficiency. At 10% efficiency, that's 100g, which is 5 cm^3 for plutonium. A cell phone batte
18.
by gji 9y ago
Cambridge (MA) is like this, but housing prices are still pretty unreasonable. You definitely need taller buildings.
19.
by gji 9y ago
Indeed, that's accurate (apart from finite temperature and interaction effects). A BEC is in some ways pretty similar to a laser, where all the photons are in the same state, even quantum mechanically. But it's important to distin
20.
by gji 9y ago
The electric field gets quickly attenuated in saltwater though, especially at high frequency: https://en.wikipedia.org/wiki/Communication_with_submarines
21.
by gji 9y ago
Nice game, but there's nothing intrinsically quantum about anything that happens. Everything is perfectly describable with classical E&M.
22.
by gji 10y ago
Andrea Morello's devices are essentially quantum dots - isolated electrons that behave like they are bound to a single atom. Unfortunately, almost all quantum dots require dilution refrigerators. These things are past liquid nitrogen a
23.
by gji 10y ago
The real evidence of this is from the last experiment under "Sequential Experiments". Essentially, you only select particles with spin-up in the z direction, then you select particles with spin-up in the x direction. So the result
24.
by gji 10y ago
I also had a very different experience, was part of various "gifted" programs from 4th grade until I graduated high school. Many of my classmates are doing extremely well (grad school/consulting/tech) - I don't thin
25.
by gji 10y ago
Regarding your first point: from my experience (working on physics experiments that depend on vacuum <10^-11 torr), the construction of the knife edge that seals against the gasket is fairly important - any chips or imperfections and the
26.
by gji 10y ago
Disclaimer: I used to work on trapped-ion systems. I hear this a lot about trapped-ion qubits, but in their current state, no technology is scalable. The usual suspects are superconducting, quantum dots, or diamond NV-based qubits, but each
27.
by gji 13y ago
Not quite the same as an ultrasonic bath. This device creates standing waves, so the antinodes (parts of the wave where the amplitude is 0) will not move. I'm pretty sure the waves created by an ultrasonic cleaner are moving. If the wa
28.
by gji 13y ago
I'm not sure fiber optics are particularly viable in the next 5-10 years as interconnects between hardware components. Adding photonics to a hardware component increases size and cost fairly significantly, which is why you don't s