3 ms·
QC is hard because it requires that the qbits be entangled with each other, but not interacting at all with the rest of the universe. This is comparable to tryi
by sbierwagen 14y ago
QC is hard because it requires that the qbits be entangled with each other, but not interacting at all with the rest of the universe. This is comparable to trying to eat rice without a fork, or chopsticks, or allowing air to touch the rice. QC is very, very hard. It is entirely possible we won't see useful QC machines for decades, or even centuries.
D-Wave has attracted scepticism because in the many press releases they've issued over the last 14 years, they have repeatedly claimed to have made breakthroughs in quantum computing that would be perhaps 200 years before their time, if they weren't lying. Like a Chinese manufacturer saying they'll be selling an $11 phone next spring that has petabytes of ram, and can run a simulation of a human brain in real time, which the phone uses for accurate voice transcription.
D-Wave have finally, finally demonstrated a machine with a working qbit system. But the qbits are strongly coupled to the environment, and the machine runs many times slower than a classical electronic computer, even in the fake benchmarking problem that is the only thing the D-Wave machine can solve.
It is an important step on the road to usable quantum computing. It is not a general-purpose quantum computer. It can't be used for prime factorization, for instance.
- danbruc 14y agoQuantum annealing can be used to factor integers [1] (if those guys are correct) but the current D-Wave machines are probably unable to factor any interesting number. Here are some more hints [2] what is possible or not. [1] http://physics.stackexchange.com/questions/11063/can-quantum-annealing-be-used-for-factorization http://physics.stackexchange.com/questions/11063/can-quantum... [2] http://physics.stackexchange.com/questions/10496/what-can-the-d-wave-quantum-computer-do http://physics.stackexchange.com/questions/10496/what-can-th...
- 8080 14y agoQuantum annealing can be used to factor integers in the same way simulated annealing or genetic algorithms can: yes, you can reduce factoring to a SAT problem and then give it to a genetic algorithm for SAT but it will probably take a geological era to factor even relatively small numbers. Quantum computers can factor N digit numbers with N^3 operations with Shor's algorithm, but no one has found a way to factor a number in polynomial time (in theory) with a quantum annealing scheme like the one allegedly implemented by the DWave. And I'm pretty confident that is neither possible.