Fundamental physics at the quantum limits of measurement

Quantum information theory and experiments provide tools to help us learn about the most elementary questions we have about the natural world—how does gravity work? What kinds of particles are the fundamental building blocks of the universe? How does quantum mechanics apply to the very early universe, or in other extreme situations like black holes?

Specifically, our work in this direction currently focuses on the application of quantum sensors and limits to their performance from both stochastic and quantum effects to understand our ability to do experiments related to these questions. Most of these experiments would necessarily be looking at extraordinarily tiny signals, for example the gravitational field of mesoscopic quantum objects, or the miniscule forces created by passing dark matter particles. Quantum mechanics itself imposes limits on how precisely a given quantity can be measured, as exemplified by Heisenberg's microscope argument. These kinds of limits have important consequences for real experiments; for example, the next generation of LIGO detectors will be operating in a regime limited by quantum measurement noise.

A particularly exciting direction which has come out of this is a program for dark matter detection using quantum optomechanical sensors. An ambitious target we have proposed is a concept for detecting dark matter passing through an array of mechanical devices, by reading out the tiny gravitational pull exerted by the dark matter on the sensors. Such an experiment would necessarily live near the quantum limits of measurement, and expand the limits of metrology at both microscopic and macroscopic mass scales.

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Team Members

  • Sohitri Ghosh
  • Jonathan Kunjummen