s1dev

6 ms·

1.
by s1dev 2y ago
When maintaining a quantum memory, you measure parity checks of the quantum error correcting code. These parity checks don't contain any information about the logical state, just (partial) information about the error, so the logical qu
2.
by s1dev 2y ago
I often wondered why MIMO was such an investigated topic. It would make sense if the Shannon limit is higher for this channel. Is there a foundational paper or review that shows this?
3.
by s1dev 2y ago
I believe that a classical radio receiver is measuring a coherent state. This is a much lower level notion than people normally think about in QEC since the physical DoF are usually already fixed (and assumed to be a qubit!) in QEC. The clo
4.
by s1dev 2y ago
Are Q-switched / pulsed lasers common in industrial applications?
5.
by s1dev 2y ago
What bank is this and are they available nationwide?
6.
by s1dev 2y ago
For a circuit of size C, the size of a fault tolerant circuit to compute the same thing is O(C polylog C) https://arxiv.org/abs/quant-ph/9906129
7.
by s1dev 2y ago
I’m generally in agreement with the anti-bash camp, but I can name about that many :) - Mutating default arguments to functions, so subsequent calls have different behavior - Somewhat particular rules around creating references vs copies -
8.
by s1dev 3y ago
A few things come to mind from more modern aircraft like the 787/A350: Fly by wire (flight envelope protection), electronically actuated control surfaces (less hydraulics / reduced complexity), bleedless engines (greater efficienc
9.
by s1dev 3y ago
I want to point out that the experiment was at Harvard in the Lukin group. There is a proposal for constant-rate encodings using large quantum low-density parity check codes via atom rearrangement which could in principle achieve such high
10.
by s1dev 3y ago
This is pretty neat! I think it's worth doing more analysis on the entropy cells separately from the entropy extractor. For example, the von Neumann extractor requires exchangeability of the input bits. Does this hold? In the setting w
11.
by s1dev 3y ago
Is there some good intuition why P-complete problems are difficult to parallelize? This is the first I've heard of it (but then again, I'm usually interested in more obscure complexity classes)
12.
by s1dev 3y ago
This is not quite true. You only need to keep the qubits at a fixed temperature as you scale the system, so the resources required to add additional qubits grow only polynomially with the system size. Once you have many qubits with a suffic
13.
by s1dev 3y ago
I hear good things about this book “how to prove it” I also like Knuth’s art of computer programming book which is more about proving correctness of algorithms In general, stuff like combinatorics, algorithms, etc I find to have a low barri
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by s1dev 4y ago
Yes. Breaking things in aviation frequently results in a body count
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by s1dev 4y ago
The correction card is legally required equipment and there are a few maintenance items that trigger a requirement to update it
16.
by s1dev 4y ago
What experimental evidence of quantum gravity is there? I like to argue for theoretical evidence of quantum gravity, but afaik there hasn’t been any experiments to rule out classical GR coupled to a quantum matter sector
17.
by s1dev 4y ago
It is worth noting that all known classical algorithms to solve this problem scale exponentially with the problem size, and fundamentally there is no reason why putting 60 or 70 qubits in the fridge is particularly more difficult than 53. T
18.
by s1dev 4y ago
I once ran across an application that had a heap footprint for which the size was fixed at runtime. The data locality loss from the indirection killed the performance. In principle, JIT could fairly transparently unbox this and have no heap
19.
by s1dev 4y ago
More or less, we're just before the finish line. About 20% lower noise and we'll be there. For every little bit past that, the overhead gets reduced immensely https://arxiv.org/abs/2207.06431
20.
A bird's-eye view of quantum error correction and fault tolerance(arthurpesah.me)
1 points by s1dev 4y ago|3 comments
21.
by s1dev 4y ago
Quantum error correction is a key ingredient for future realizations of fault-tolerant quantum computers. Physics is local, so errors in far separated regions of the device are only slightly correlated. In this setting, threshold theorems c
22.
by s1dev 4y ago
From a theoretical point of view, this is evidence that quantum computing is a more powerful model of computation. I think it would be hard to argue that a model of computation that can solve more problems is any less useful. Applications l
23.
by s1dev 4y ago
I don’t think anyone does grad school expecting that it’s going to be a good investment. Most people I know do it because they can’t imagine themselves doing anything other than research. Is it a waste if afterwards you just get some 9-5 so
24.
by s1dev 4y ago
There is an extremely broad range of scaling between linear and exponential… Even in architectures with nearest neighbor gates, the (multiplicative) overhead stemming from error correction will only need to be logarithmic in the size of the
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by s1dev 5y ago
Here's a few references https://doi.org/10.1145/2492101.1555372 https://doi.org/10.1145/2786763.2694348 https://doi.org/10.1109/DSN.2015.57
26.
by s1dev 5y ago
A consumer PC should see a single bit error roughly once a week. That’s hardly non-existent
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by s1dev 5y ago
That's not quite true. The dimension of the ambient space is constrained to be exactly 10 (in strings, 11 in M-theory) by consistency considerations. The important question is what is the geometry of the extra dimensions, if they exist
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by s1dev 6y ago
It's generally expected that the spacetime geometry is emergent as some coherent state of gravitons Unpacking that statement a bit: - In quantum mechanics there is a procedure called "quantization" that takes in a classical t
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by s1dev 6y ago
Of course you wouldn't actually put them in Texas, but since this seems to be missed a lot: It hails reasonably frequently in the Midwest (incl. Texas)
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by s1dev 6y ago
it's one instruction in the generated code and we can reasonably expect the branch predictor to do the right thing, but branches and error handling can inhibit vectorization which is a much higher performance cost. While in this partic

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