Quantum Supremacy, What Is It Anyhow?

**What Is Quantum Supremacy, and Why Is It Such a Computing Milestone?**

Excerpts and salient points ~

+ Quantum supremacy means only that researchers have been able to use a quantum computer to perform a single calculation that no conventional computer, even the biggest supercomputer, can perform in a reasonable amount of time.

+ In the case of Google, this calculation involved checking whether the output of an algorithm for generating random numbers was truly random.

+ The researchers were able to use a quantum computer to perform this complex mathematical calculation in three minutes and 20 seconds, according to the paper. They say it would have taken Summit 3—an IBM-built machine that is the world’s most powerful commercially-available conventional computer—about 10,000 years to perform the same task.

*For the moment, the public-private key encryption techniques on which bitcoin and other cryptocurrencies are based cannot be broken by a quantum computer. But Google’s researchers, in their paper, predict that quantum computing power will continue to advance at a “double exponential rate,” so those bitcoins may not be safe for all that much longer.*

+ What’s so special about Sycamore? Sycamore is not the world’s largest quantum processor. Google itself had produced a 72 qubit system last year. And Rigetti, a California startup working on quantum computers, has said it plans to have a 128 qubit system ready soon. But Google’s researchers said they made major advances in how long its qubits can remain in a quantum state and how each qubit interacts with the other qubits next to it.

+ That’s important because when qubits fall out of a quantum state, they introduce errors into the calculations the quantum computer is performing. Those errors then have to be corrected by using additional qubits. These error rates are the reason that your laptop can beat today’s quantum computers in getting a correct answer to most mathematical problems.

Source:* FORTUNE. Jeremy Khan, What Is Quantum Supremacy, and Why Is It Such a Computing Milestone?*

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