IBM Raises the Bar with a 50-Qubit Quantum Computer (technologyreview.com)

IBM said on Friday it has created a prototype 50 qubit quantum computer as it further increases the pressure on Google in the battle to commercialize quantum computing technology. The company is also making a 20-qubit system available through its cloud computing platform, it said. From a report: The announcement does not mean quantum computing is ready for common use. The system IBM has developed is still extremely finicky and challenging to use, as are those being built by others. In both the 50- and the 20-qubit systems, the quantum state is preserved for 90 microseconds -- a record for the industry, but still an extremely short period of time. Nonetheless, 50 qubits is a significant landmark in progress toward practical quantum computers. Other systems built so far have had limited capabilities and could perform only calculations that could also be done on a conventional supercomputer. A 50-qubit machine can do things that are extremely difficult to simulate without quantum technology. Whereas normal computers store information as either a 1 or a 0, quantum computers exploit two phenomena -- entanglement and superposition -- to process information differently.

Comments

encryption

[Anonymous Coward]

One of the reasons the three letter agencies like to store even encrypted communication is that quantum computers will allow breaking encrypted data in ways that classical computers can't do in any practical sense. An example is Shor's Algorithm for factoring numbers, which runs efficiently in a practical amount of time on a quantum computer and could be used to break public key crypto. If they have saved the current encrypted text they can later break that when quantum computing hits.

Quantum computing is not quite there yet but it is coming up the well.

Re:encryption

[TechyImmigrant]

The practical defenses against the hypothesized quantum cryptopocalypse are:
Grover Issues:
A) Double the key size for symmetric algorithms, MACs
B) Double your hash sizes (you can finesse in which situations, but for practical purposes just double them all)

Shor Issues:
C) Use Hash based signatures for certificates.
D) Replace RSA, DH and ECDH with something else. Lattice crypto is a contender. Some with claim NTRU is fine, but it's not practical.

You shouldn't have been using DSA in the first place. So that's moot.

The dilemma is that the fix for asymmetric key crypto is not clear. Various lattice proposals have come along and been broken. RWLE is a PITA to implement (although that might be getting better soon with some stuff I've seen) and generally we don't know what it's going to be.

On the positive side, it's all BS. They will not build a quantum computer capable of breaking RSA any time soon. TFS makes is sound they they got from 2 bits to 50 bits and so 256 bits are only a short way off. This is grossly misrepresenting the situation. You can make some fragile qbits cohere but you can't do iterative logic on it., You can make a reliable, error corrected qbit, but you can't make reliable error corrected qubits into a memory on which you can perform the quantum logic needed to implement Shor's algorithm. These are the barriers to cross and as far as I can tell, they have remained unsolved for many years. Upping the number of non-ecc qbits doesn't move us towards breaking public key crypto.

I may or may not be proven wrong, but we will have the symmetric upgrades deployed in most new silicon pretty soon and the conference circuit will remain well attended while the lattice crypto work continues. So there will be lots more travel to nice places.