jdrov

5 ms·

1.
by jdrov 8y ago
There are a few key differences in our work. First, it's a very different system; the prior experiments were done using trapped ions, and "defects" (nitrogen-vacancy centers) in diamond, while our system used nuclear spins. T
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by jdrov 8y ago
Thanks for the kind words. I've focused a good deal in the past few years on teaching/communication (see my profile for a link to some of my basic-physics lectures for student taking the MCAT), and I'm very grateful for the o
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by jdrov 8y ago
See my response here, about the way in which the response frequency depends on both the nature of the drive and the nature of the internal interactions in the system: https://news.ycombinator.com/item?id=16999031 The idea o
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by jdrov 8y ago
This is a good question. The "directions" you mention would, in our system, typically be considered to depend on the nature of the drive. For instance, if you repeatedly rotate the magnetization by 180 degrees, you can imagine the
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by jdrov 8y ago
I'm not confident that what we're observing are "lossless vibrations," but it is the case that there is something that is "lossless" about what we call "unitary evolution." The signal we start with de
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by jdrov 8y ago
I notice a lot of questions here about piezoelectric oscillators, which I realize now makes sense given this community. A key difference to understand here is that the phrase "time crystal" is referring to a state of a particular
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by jdrov 8y ago
We use a solenoid to drive magnetic fields in our sample (RF frequencies, near field), but yes, we do often envision an absorption or emission event by a given nuclear spin as it changes its spin state in the presence of an even stronger, s
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by jdrov 8y ago
Let me know if my synopsis above helps, or if you have any specific questions from a high-energy theory point of view. Given your background, you might appreciate that we ran many simulations, to characterize the sample, understand our earl
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by jdrov 8y ago
Here are Arxiv pre-prints, which are still a bit different from the published versions: https://arxiv.org/abs/1802.00126 https://arxiv.org/abs/1802.00457
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by jdrov 8y ago
Duplicating my reply from here: https://news.ycombinator.com/item?id=16996428 See also the reply here: https://news.ycombinator.com/item?id=16996766 It was shown after the original proposal in 2012 that the
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by jdrov 8y ago
Let me know if my attempted synopsis above is helpful or not... I think I can confidently say that the crystal does not travel backwards in time (or forwards in time any faster than the normal rate, as has been pointed out). However, it is
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by jdrov 8y ago
Admittedly, if you asked me 20 years ago which one of "time crystal" or "flux capacitor" were actually from a movie called "Back to the Future," I am not confident I would answer correctly.
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by jdrov 8y ago
You're right that the terminology has been tricky to contend with, although it's hard to say what a 'least-confusing' name would be. Other names for the phenomenon include "Pi spin glass" and "Floquet time
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by jdrov 8y ago
It was shown after the original proposal in 2012 that these signatures can only be observed in "non-equilibrium" systems, so we are actually supplying the pulses, which drive the ticking. The quantum basis for the robust frequency
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by jdrov 8y ago
There are a few questions about an "overview," so I'll give that a shot here. This is some imagery I've been using recently, about how our observed signatures are related to crystals. Sometimes physicists think of phase
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by jdrov 8y ago
That is the kind of thing we are working on understanding right now, and research proposals into this (so-called "quantum metrology") are underway. Is it definitely the case that radio-frequency pulse sequences (related to those u
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by jdrov 8y ago
I'm not an expert in quartz, but I'd assume there are physical "mechanical" oscillations with a hopefully-small distribution of frequencies around a given frequency, which is known to some particular degree of accuracy.
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by jdrov 8y ago
The state of the nuclear spin (up or down, or superposition) is definitely something that has been proposed as a quantum bit ("q-bit"), and many quantum computer proposals have used the nuclear spin as their proposed q-bit. The tr
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by jdrov 8y ago
As far as I know, there are no implications for how physical structures are organized in space (e.g. spatial crystal lattices). The signatures we've observed were in a crystal with a very well-characterized lattice structure, and could
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by jdrov 8y ago
Sean is the kind of advisor that makes being a graduate student both exciting and sustainable. He's always upbeat, supports us professionally, etc., so it's always particularly sad for me to hear from students who have had bad exp
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by jdrov 8y ago
First author here -- happy to take any questions!