tagrun

20 ms·

121.
by tagrun 7y ago
I'm not sure what you're trying to imply here. I'm not sure if it's relevant either, as this is about the implementation of the same instruction set (AVX/AVX2) on Intel and AMD, whereas you say "not Intel <-
122.
by tagrun 7y ago
And how exactly does that plot show that AMD's AVX instructions are faulty?
123.
by tagrun 7y ago
I can't tell if you're being naive or deliberately perpetuating an Intel FUD. You're being part of the problem by doubling down on some ambiguous comment (which is not even based on any real test) as if there actually is a pr
124.
by tagrun 7y ago
Except HPC clusters do need all the Spectre/Meltdown fixes and more. Those are shared environments (with the exception of a handful of people who got research grants for their own internal clusters). In fact, hyper-threading has also
125.
by tagrun 7y ago
I don't know what exactly your belief is rooted on (clearly not physics), but of course you're free to put your money wherever you want, just be aware that: - Qubits are not boolean. Classical error correction does not work in qua
126.
by tagrun 7y ago
Well, I'm envious that you didn't have to deal with those people. I am involved on the theory side of the implementation of different kinds of solid state qubits, so you may say I'm biased, but the question really isn't
127.
by tagrun 7y ago
Actually, we had people who claimed for about four decades that it is fundamentally impossible to have quantum speed up, basically equating it to a perpetual motion machine. We still have such famous people around (who aren't physicis
128.
by tagrun 7y ago
Then I don't know which crackpot "interpretation" (that doesn't even agree with the experiments, unlike MWI etc) you are referring to, but you can rest assured that nothing in these experiments or condensed matter physi
129.
by tagrun 7y ago
No. An interpretation is just that. No matter what interpretation you use, the experimental measurement results are the same. If they don't give the same results, it won't be interpretations: you'd have two competing theories
130.
by tagrun 7y ago
It's a very different thing. I'm not just talking about the age of the theory. I'm talking about the length of the period during which it was tested so many times, to the level of precision that no other theory got tested and
131.
by tagrun 7y ago
Quantum mechanics is about a 100 years old, and no violation has even been observed in laboratory, particle accelerators or outer space. The quantum theory is the most accurate theory we ever had in the history, tested to less than 1 in a b
132.
by tagrun 7y ago
They're using a "clever trick" to approximately evaluate the overall gate from this paper https://arxiv.org/abs/1807.10749 which is computationally cheaper than doing a "brute force" simulation
133.
by tagrun 7y ago
It's pretty easy and requires no physics, actually. Here's a simple, extended version. A quantum gate is, mathematically speaking, a matrix. For a given physical system, of fixed number of qubits, obtaining that matrix on a classi
134.
by tagrun 7y ago
Again, no. It is a trivial fact that on a classical computer, you can simulate a quantum computer in time that grows linearly in circuit depth, in principle (as in the case of the "naive" way I mentioned above). No one in doing qu
135.
by tagrun 7y ago
That sentence actually reads " Schrödinger–Feynman algorithm becomes exponentially more computationally expensive with increasing circuit depth" which is true (because the paths in a path integral in a discrete setting would grow
136.
by tagrun 7y ago
No idea where exactly you got that idea (feel free to quote any part of the paper), but no, it isn't. Even the brute force "simulation" of a quantum computer is like UN...U2.U1 where Us are unitarity matrices. The hard part i
137.
by tagrun 7y ago
Physicists here. Note that they say it scales linearly in circuit depth (which is a trivial fact, and has always been true for classical simulations of quantum computers which are optimal in that regard --in fact, that is the case when do
138.
by tagrun 7y ago
Right. We're all equal but some people are more equal than others. So it's OK they're above the rules for commoners. Twitter is rationalizing their unequal treatment of people for the sake of their network traffic and $$$, bu
139.
by tagrun 7y ago
And it takes 2 years for most students to meet the MSc requirements (basically they need to complete the coursework), not 4 years, barring some special cases. Again, I'm talking about the common practice, not the handful of exceptional
140.
by tagrun 7y ago
What exactly isn't true about it? In all institutions that I know all, students are given MSc status as soon as they complete the requirements, not M Phil (never even heard of it). Some students leave the school after that point, but i
141.
by tagrun 7y ago
That's because in the US, PhD is actually the combination of masters degree (typically 2 years) and PhD (typically 3-4 years) in other countries. At least in sciences, US universities don't typically even offer a MSc program; peop
142.
by tagrun 7y ago
This is like saying that voltage is a scalar real number, which explains nothing about the physics of electromagnetism, and in my opinion is probably the worst way to explain physics of anything. It especially tells nothing useful given the
143.
by tagrun 7y ago
And there's the pesky issue of readout errors, which tends to bad.
144.
by tagrun 7y ago
That version of the though experiment is known as "quantum suicide": https://en.wikipedia.org/wiki/Quantum_suicide_and_immortalit...
145.
by tagrun 7y ago
When you say chip architecture, I assume you mean how to assemble together qubits like an integrated circuit. Here's one proposal for silicon based qubits: https://www.nature.com/articles/s41467-017-01905-6 Microw
146.
by tagrun 7y ago
There is a scalability problem but due to different reasons. See my other comment in this thread for details. Classical circuitry is an issue, but not as much as you think. What happened is Martinis' group and others moved forward with
147.
by tagrun 7y ago
We do want the chip to be "large" eventually. The scalability doesn't have anything with those, however. Refrigerators are pretty large and these devices are really really tiny; also qubits shouldn't be spaced "far&
148.
by tagrun 7y ago
Physicists here. In practice, a qubit is a two-level physical system. It can be spin state of an electron, polarization of a photon, lowest two energy states of an atom or an electron in quantum dot/well trap potential, the charge stat
149.
by tagrun 7y ago
- Cross-entropy is used for roughly estimating the fidelity (see arXiv:1608.00263), which is independent of the problem they're solving. You're confusing it with the overall distribution of the readout states, which is the hard pr
150.
by tagrun 7y ago
Quantum supremacy was mainly coined as a milestone as a response to certain vocal famous people (almost none physicists, which was the problem) who have been skeptical about quantum computers at a fundamental level . That is to say, there

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