4 quantum sensing quantum technology has advantages

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(4) Quantum sensing. Quantum technology has advantages for some kinds of sensing. Quantum systems can sense weak forces with better sensitivity and higher spatial resolution than other sensing technologies [ 21 ]; thus quantum sensing could have relatively near-term high-impact applications, to medicine for example. Quantum communication, networking, randomness expansion, and sensing cannot be cleanly separated from quantum computing, because similar technological challenges are faced by all these quantum-information goals. Nevertheless, I’ll give short shrift to these topics here. 6 Quantum speedups? What I would like to focus on instead is whether quantum computers will have widely used applications, particularly in the relatively near term. The main question is: When will quantum computers be able to solve problems we care about faster than classical computers, and for what problems? Accepted in Q u a n t u m 2018-07-30, click title to verify 6
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At least in the near term quantum computers are likely to be special purpose devices, which most users will access via the cloud. When we speak of a quantum speedup, we typically mean that the quantum computer solves the problem faster than competing classical computers using the best available hardware and running the best algorithm which performs the same task. (Arguably, though, quantum technology might be preferred even if classical supercomputers run faster, if for example the quantum hardware has lower cost and lower power consumption.) In any case, we should recognize that the power of classical computers will continue to increase, with exascale systems (surpassing 10 18 FLOPS) expected to be available in a few years. Quantum computers are striving to catch up with a moving target, as both classical hardware and classical algorithms continually improve. A few years ago I spoke enthusiastically about quantum supremacy as an impending milestone for human civilization [ 22 ]. I suggested this term as a way to characterize com- putational tasks performable by quantum devices, where one could argue persuasively that no existing (or easily foreseeable) classical device could perform the same task, disregard- ing whether the task is useful in any other respect. I was trying to emphasize that now is a very privileged time in the coarse-grained history of technology on our planet, and I don’t regret doing so. But from a commercial perspective, obviously we should pay at- tention to whether the task is useful! Quantum supremacy is a worthy goal, notable for entrepreneurs and investors not so much because of its intrinsic importance but rather as a sign of progress toward more valuable applications further down the road. We should also bear in mind that, because of the imperfect performance of NISQ technology, it may be hard to validate that a quantum computer is really giving the right answer. That’s particularly true for the quantum simulation problems physicists are excited about. So it’s important for researchers to continue seeking better methods for verifying the output of a quantum computer.
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  • Fall '13
  • Xue
  • Nature, Quantum computer, Quantum entanglement, Quantum information science

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