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I fear it is my obligation to point out this excellent screed by Scott Lockin: "Quantum computing as a field is obvious bullshit". A beautiful excerpt from the

I fear it is my obligation to point out this excellent screed by Scott Lockin: "Quantum computing as a field is obvious bullshit". A beautiful excerpt from the article: When I say Quantum Computing is a bullshit field, I don’t mean everything in the field is bullshit, though to first order, this appears to be approximately true. I don’t have a mathematical proof that Quantum Computing isn’t at least theoretically possible. I also do not have a mathematical proof that we can or can’t make the artificial bacteria of K. Eric Drexler’s nanotech fantasies. Yet, I know both fields are bullshit. Both fields involve forming new kinds of matter that we haven’t the slightest idea how to construct. Neither field has a sane ‘first step’ to make their large claims true. ..... “quantum computing” enthusiasts expect you to overlook the fact that they haven’t a clue as to how to build and manipulate quantum coherent forms of matter necessary to achieve quantum computation. A quantum computer capable of truly factoring the number 21 is missing in action. In fact, the factoring of the number 15 into 3 and 5 is a bit of a parlour trick, as they design the experiment while knowing the answer, thus leaving out the gates required if we didn’t know how to factor 15. The actual number of gates needed to factor a n-bit number is 72 x n^3; so for 15, it’s 4 bits, 4608 gates; not happening any time soon. [1]: https://scottlocklin.wordpress.com/2019/01/15/quantum-computing-as-a-field-is-obvious-bullshit/ https://scottlocklin.wordpress.com/2019/01/15/quantum-comput...

TheRealPomax 6y ago
except we already use qubits in the real world, and we already use entangled pairs in banking, so it's not really all that bullshit anymore. Quantum computers with a significant number (e.g thousands, but really, millions) of qubits, however, are still quite a ways away. But clearly not in the realm of bullshit anymore.
- haltingproblem 6y ago
  I would love to learn more, please share any relevant useful links. Edit: Cursorily googled and did not find a reference for usage but plenty of papers talking about potential applications. Might be wrong though.
- mikeodds 6y ago
  Is this referencing quantum cryptography being used in banking? Any good sources for more info on this, it sounds really interesting.
  - Moodles 6y ago
    I'm no expert in quantum computation but my understanding is that using qubits for quantum computing is totally different to using qubits to exchange secrets as in cryptographic key exchange. The latter is using the property that observing the quantum state changes the state, thus an eavesdropper can't interfere when you send qubits over the wire to exchange a secret. That seems very different to arranging large amounts of qubits in a particular way to do useful calculations. Even in the key exchange case, I'm personally pretty skeptical of its real-world usefulness because it's not really solving a problem we actually have: public key cryptography (even slower post-quantum variants) work just fine and seem a bit more practical than building some quantum infrastructure to send entangled qubits over to augment a secret that's already exchanged.
    - haltingproblem 6y ago
      That was my initial reaction - quantum entanglement for crypto is not same as quantum computing and furthermore a hammer in search of a problem that does not exist (yet).
sushisource 6y ago
Obviously this isn't the strongest argument in the world, but, if the whole field is so bullshit why has anyone bothered putting effort into post-quantum encryption? What's the point if quantum computers will never materialize?
- alexw91 6y ago
  It's theoretically possible for someone to record encrypted traffic today, keep a copy of it for a decade or two until quantum computers are available, and then decrypt it in the future using the quantum computer. If you have data today, that needs to be secure for more than a few decades, you may want to move to post quantum crypto soon to stop that potential leak.
- haltingproblem 6y ago
  Lets rephrase it in terms of product-market fit - what problem is post-quantum encryption going to solve for people to put effort into it? BTW, the term post-quantum encryption is delicious because we had never had the quantum encryption era. Like the post-high speed era rail in the US ;)
  - caf 6y ago
    The sense this term is using 'quantum' is as a shorthand for a point in time, where attacking cryptosystems using quantum computers becomes feasible. So you can talk ante-quantum and post-quantum in this sense, but it makes little sense to talk about just 'quantum', in exactly the same way that we schedule a lot of things AM and PM but very little for precisely noon.

TheRealPomax 6y ago

except we already use qubits in the real world, and we already use entangled pairs in banking, so it's not really all that bullshit anymore. Quantum computers with a significant number (e.g thousands, but really, millions) of qubits, however, are still quite a ways away. But clearly not in the realm of bullshit anymore.

haltingproblem 6y ago
I would love to learn more, please share any relevant useful links. Edit: Cursorily googled and did not find a reference for usage but plenty of papers talking about potential applications. Might be wrong though.
mikeodds 6y ago
Is this referencing quantum cryptography being used in banking? Any good sources for more info on this, it sounds really interesting.
- Moodles 6y ago
  I'm no expert in quantum computation but my understanding is that using qubits for quantum computing is totally different to using qubits to exchange secrets as in cryptographic key exchange. The latter is using the property that observing the quantum state changes the state, thus an eavesdropper can't interfere when you send qubits over the wire to exchange a secret. That seems very different to arranging large amounts of qubits in a particular way to do useful calculations. Even in the key exchange case, I'm personally pretty skeptical of its real-world usefulness because it's not really solving a problem we actually have: public key cryptography (even slower post-quantum variants) work just fine and seem a bit more practical than building some quantum infrastructure to send entangled qubits over to augment a secret that's already exchanged.
  - haltingproblem 6y ago
    That was my initial reaction - quantum entanglement for crypto is not same as quantum computing and furthermore a hammer in search of a problem that does not exist (yet).

sushisource 6y ago

Obviously this isn't the strongest argument in the world, but, if the whole field is so bullshit why has anyone bothered putting effort into post-quantum encryption? What's the point if quantum computers will never materialize?

alexw91 6y ago
It's theoretically possible for someone to record encrypted traffic today, keep a copy of it for a decade or two until quantum computers are available, and then decrypt it in the future using the quantum computer. If you have data today, that needs to be secure for more than a few decades, you may want to move to post quantum crypto soon to stop that potential leak.
haltingproblem 6y ago
Lets rephrase it in terms of product-market fit - what problem is post-quantum encryption going to solve for people to put effort into it? BTW, the term post-quantum encryption is delicious because we had never had the quantum encryption era. Like the post-high speed era rail in the US ;)
- caf 6y ago
  The sense this term is using 'quantum' is as a shorthand for a point in time, where attacking cryptosystems using quantum computers becomes feasible. So you can talk ante-quantum and post-quantum in this sense, but it makes little sense to talk about just 'quantum', in exactly the same way that we schedule a lot of things AM and PM but very little for precisely noon.