Quantum Supremacy, Not Happening
Quantum Supremacy Is Unlikely, Scientist Says
Excerpts and salient points ~
+ Due to superposition, a quantum computer with 100 qubits can represent 2100 solutions simultaneously. For certain problems, this exponential parallelism can be harnessed to create a tremendous speed advantage. Some code-breaking problems could be solved exponentially faster on a quantum machine, for example.
+ There is another, narrower approach to quantum computing called quantum annealing, where qubits are used to speed up optimization problems. D-Wave Systems, based in Canada, has built optimization systems that use qubits for this purpose, but critics also claim that these systems are no better than classical computers.
+ Regardless, companies and countries are investing massive amounts of money in quantum computing. China has developed a new quantum research facility worth US$10 billion, while the European Union has developed a €1 billion ($1.1 billion) quantum master plan. The United States’ National Quantum Initiative Act provides $1.2 billion to promote quantum information science over a five-year period.
+ Breaking encryption algorithms is a powerful motivating factor for many countries — if they could do it successfully, it would give them an enormous intelligence advantage. But these investments are also promoting fundamental research in physics.
Google announced this fall to much fanfare that it had demonstrated “quantum supremacy” — that is, it performed a specific quantum computation far faster than the best classical computers could achieve. IBM promptly critiqued the claim, saying that its own classical supercomputer could perform the computation at nearly the same speed with far greater fidelity and, therefore, the Google announcement should be taken “with a large dose of skepticism.”
+ Many companies are pushing to build quantum computers, including Intel and Microsoft in addition to Google and IBM. These companies are trying to build hardware that replicates the circuit model of classical computers. However, current experimental systems have less than 100 qubits. To achieve useful computational performance, you probably need machines with hundreds of thousands of qubits.
+ The mathematics that underpin quantum algorithms is well established, but there are daunting engineering challenges that remain.
+ For computers to function properly, they must correct all small random errors. In a quantum computer, such errors arise from the non-ideal circuit elements and the interaction of the qubits with the environment around them. For these reasons the qubits can lose coherency in a fraction of a second and, therefore, the computation must be completed in even less time. If random errors — which are inevitable in any physical system — are not corrected, the computer’s results will be worthless.
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