Quantum Negativity For Precision Optical Measurements

Researchers have shown that quantum particles can carry an unlimited amount of information about things they have interacted with. The results could enable far more precise measurements and power new technologies, such as super-precise microscopes and quantum computers.

Metrology is the science of estimations and measurements. If you weighed yourself this morning, you’ve done metrology. In the same way, as quantum computing is expected to revolutionize the way complicated calculations are done, quantum metrology, using the strange behavior of subatomic particles, may revolutionize the way we measure things.

We are used to dealing with probabilities that range from 0% (never happens) to 100% (always happens). To explain results from the quantum world however, the concept of probability needs to be expanded to include a so-called quasi-probability, which can be negative. This quasi-probability allows quantum concepts such as Einstein’s ‘spooky action at a distance’ and wave-particle duality to be explained in an intuitive mathematical language. For example, the probability of an atom being at a certain position and traveling with a specific speed might be a negative number, such as –5%. An experiment whose explanation requires negative probabilities is said to possess ‘quantum negativity.’ The scientists have now shown that this quantum negativity can help make more precise measurements.

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