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New insights into quantum measurements

25 April 2019

Researchers from the University of Bristol have shed new light on the process of quantum measurement, one of the defining, and most quantum features of quantum mechanics.

As reported in Physical Review Letters, Dr Paul Skrzypczyk and Professor Noah Linden looked at the way in which we gain information about the world at the quantum scale through the process of measurement. This work has been selected as an Editor’s Suggestion “due to its particular importance, innovation, and broad appeal.”

They found that the ability for a measurement to be highly informative is intimately related to how robust the measurement is to imperfections or noise. They also uncovered a connection to a branch of quantum information science which concerns communication. Viewing the measurement as a special type of communication channel, they found that its ability to communicate well is related in the same way to how robust the measurement is to imperfections.

“Understanding the process of measurement in quantum mechanics is a fundamental question, that has been extensively studied in the past,” said Dr Skrzypczyk, from Bristol’s Quantum Information Institute.

Prof Linden added: “As with any basic question, a true understanding is going to be multifaceted. We have added a new facet to our understanding of the measurement process, by linking the informativeness of a measurement to its robustness against noise and to quantum communication theory.”  

Quantum mechanics is a field of research that has a reputation for being counterintuitive. This latest study is likely to inspire further investigation, since the links uncovered in this work appear to have analogues in other contexts, concerning other aspects of quantum mechanics beyond the measurement process.

Dr Skrzypczyk added: “We would like to explore the generality of our results more widely in quantum mechanics and in quantum information science. Our initial explorations hint that we have uncovered a first example of a much more general phenomenon.  It is very exciting to embark on our investigations of just how general they might ultimately be.”

Further information

Paper: ‘Robustness of Measurement, Discrimination Games, and Accessible Information’, by Paul Skrzypczyk and Noah Linden, Physical Review Letters.

Quantum Information Theory at Bristol
The Quantum Information Theory group spans the Schools of Mathematics and Physics. Group members have interests in all theoretical aspects of quantum information science, including fundamental aspects of quantum mechanics; mathematical underpinnings of quantum information theory; quantum algorithms; quantum computation; quantum nonlocality; and applications of quantum information theory to other disciplines.
Bristol Quantum Information Institute
Quantum information and its translation into technologies is one of the most exciting research activities in science and technology today. Long at the forefront of the growing worldwide activity in this area, the Bristol Quantum Information Institute crystallises our research across the entire spectrum, from theory to technology. With our expert cross-disciplinary team, including founders of the field, we have expertise in all major areas of theoretical quantum information science and in experiment. We foster partnerships with the private sector and provide superb teaching and training for the future generation of quantum scientists and engineers and the prototypes of tomorrow.
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