101–110 of 116 posts
Presenting the pictures of a quantum computer with adbobe flash is an impressive combination of technologies. I hope they are use a different technology stack to develop the OS of that machine ;-)
Talking about the websites stack instead of the content is the HN equivalent of bike-shedding. It sounds like a contribution but it isn't. https://en.wiktionary.org/wiki/bikeshedding
At what point do we no longer trust public key cryptography (RSA)? Where's the break point?
> It is estimated that 2048-bit RSA keys could be broken on a quantum computer comprising 4,000 qubits and 100 million gates. Experts speculate that quantum computers of this size may be available within the next 20-30 years. https://www.entrust.com/wp-content/uploads/2013/05/WP_Quantu... The paper is from 2009, so ~2030 to break 2048-bit RSA seems about right. If they can double the number of qubits every two years,…
How many qubit does it take to crack an AES 192 key?
More important is the fact that it's a very long-running application: it requires to you keep over 192 qubits coherent for a very long time, which is probably an order of magnitude or more in error correction requirements.
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>Also, you have to consider that once you get a quantum computer that can break 2048-RSA, you'll be able to break all the encrypted communications you've stored in the past few years, too isn't that what PFS is supposed to prevent?
PFS can slow it down a bit, but not much. Assuming before PFS everyone changed their keys every 3 years, and with PFS they change them every 2 weeks, then it should be about 80x harder (slower to break the encryption). 80x harder may seem like a lot but it's not that much in the context of quantum computers. Also, PFS uses 256-bit ECC, which only requires a 512-qubit quantum computer to break it. So it's possible tha…
Grover's algorithm is a quadratic, not exponential speedup. It may require 512 qubits, but it still requires 2^128 time.
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In fact, the smallest quantum error-correcting code using qubits uses only five qubits. [1] So you could fit 10 of these codewords into 50 qubits. But that's not right. At least two more qubits are needed for fault-tolerant error correction. So that means you could fit nine codewords into 50 qubits (since 9x5+2=47 But that's not right. There exist more efficient codes that put multiple encoded qubits into a single co…
I recently had a conversation with a Microsoft quantum researcher, and this a close approximation to his answer. I just wanted a number. It's complicated.
If quantum computing improves as it had been, how does this affect Bitcoin and ethereum as we now know it? Could the blockchain be compromised by a malicious actor who has much less than the majority?
My prediction: at some point Bitcoin will go through an upgrade process to transfer user wallets to a key pair based on a quantum resistant public key algorithm. Users will be given a time frame to transmit their coins to the new wallets, and after that time is expired, EC-based wallets will not be considered valid transaction sources any longer. Classic cash conversion in the digital age.
Quantum computing reminds me of time travel for all the same reasons. This is not a quick win. How would you even validate you built a quantum computer?
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I just saw a talk by I forgot which bell labs engineer was on the transistor team. He told it took two or more years to get the errors to a useful level. It's easy to think transistor are magic solid devices, they were not.
But as they are analog devices, there are no errors with transistors There are manufacturing defects, there are inefficient designs, inefficient production methods, poor circuit designs (like using them in common base - not wrong depending on the situation - instead of common emitter)
Do you think this can f k up RSA and render our industry obsolete?
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You don't need bytes to do computation.
Wouldn't a qubyte be 8 qubits?
We may actually need a new word for 2 qubits (dual-qubits? dubits?) because it seems 2 qubits are enough to break 1-bit of encryption, and I think I've read it's enough to simulate 1 atom, too.