Quantum supremacy: A three minute guide
Google says they have reached 'quantum supremacy' with their quantum computer 'Sycamore'. Nature reporter Elizabeth Gibney explains what this means, why IBM disagree, and the significance for quantum computing.
量子霸權（quantum supremacy），或稱量子計算優越性，是指用量子計算機解決古典電腦實際解決不了的問題，問題本身未必需要有實際應用。量子優勢（quantum advantage）則是指量子電腦在解決實務問題上能比古典電腦重啟而帶來的優勢，從計算複雜性理論的角度來說，這通常代表量子電腦相對最佳古典演算法的加速是超多種式的。這個術語最初是由約翰·普里斯基爾（John Preskill）所提出的，但量子計算優勢的概念（特別是用於模擬量子系統）可以返回到尤里·馬寧（1980）和理察·費曼（1981）提出的量子計算建議。
秀爾演算法能在量子計算機上以多個式時間執行整體的因數分解，和已知的古典演算法具有超多重式加速。一般認為使用古典資源分解積分很困難，而嚴謹的證明尚未出現。缺乏古典計算這影響了常見的量子優越性問題：Aaronson和Arkhipov的玻色子抽樣問題（玻色子抽樣），D-Wave的專門沮喪的簇循環問題，以及隨機量子電路抽樣問題。
像整數分解一樣，基於合理的複雜度假設，用古典電腦對隨機量子電路的輸出分布進行抽樣是困難的。Google先前宣布，計劃在2017年底之前用含有49個超導量子位元的陣列解決這個問題，以展示量子優越性。 在那之後，Intel、IBM、Google分別宣布了49、53、72個量子位元的系統。
2020年12月4日，中國科學技術大學發布使用76個光子的量子計算機“九章”，並宣布實現量子優越性，使中國成為全球第二個實現“量子優越性”的國家。
In quantum computing, quantum supremacy or quantum advantage is the goal of demonstrating that a programmable quantum device can solve a problem that no classical computer can solve in any feasible amount of time (irrespective of the usefulness of the problem).
Conceptually, quantum supremacy involves both the engineering task of building a powerful quantum computer and the computational-complexity-theoretic task of finding a problem that can be solved by that quantum computer and has a superpolynomial speedup over the best known or possible classical algorithm for that task. The term was coined by John Preskill in 2012, but the concept of a quantum computational advantage, specifically for simulating quantum systems, dates back to Yuri Manin's (1980) and Richard Feynman's (1981) proposals of quantum computing. Examples of proposals to demonstrate quantum supremacy include the boson sampling proposal of Aaronson and Arkhipov, D-Wave's specialized frustrated cluster loop problems, and sampling the output of random quantum circuits.
A notable property of quantum supremacy is that it can be feasibly achieved by near-term quantum computers, since it does not require a quantum computer to perform any useful task or use high-quality quantum error correction, both of which are long-term goals. Consequently, researchers view quantum supremacy as primarily a scientific goal, with relatively little immediate bearing on the future commercial viability of quantum computing. Because this goal, building a quantum computer that can perform a task that no other existing computer feasibly can, can become more difficult if classical computers or simulation algorithms improve, quantum supremacy may be temporarily or repeatedly achieved, placing claims of achieving quantum supremacy under significant scrutiny. Wikipedia
Click to Read --> 6 Things Quantum Computers Will Be Incredibly Useful For
Click to Read --> 6 Things Quantum Computers Will Be Incredibly Useful For
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