PIRSA:14030110 Scientific Series Quantum Foundations

DOI10.48660/14030110

Series: Quantum Foundations

Lundeen, J. (2014). Seeing is Believing: Direct Observation of a General Quantum State. Perimeter Institute. https://pirsa.org/14030110

Lundeen, Jeff. Seeing is Believing: Direct Observation of a General Quantum State. Perimeter Institute, Mar. 17, 2014, https://pirsa.org/14030110 

@misc{ pirsa_PIRSA:14030110,
  doi = {10.48660/14030110},
  url = {https://pirsa.org/14030110},
  author = {Lundeen, Jeff},
  keywords = {Quantum Foundations},
  language = {en},
  title = {Seeing is Believing: Direct Observation of a General Quantum State},
  publisher = {Perimeter Institute},
  year = {2014},
  month = {mar},
  note = {PIRSA:14030110 see, \url{https://pirsa.org}}
}

Abstract

Central to quantum theory, the wavefunction is a complex distribution associated with a quantum system. Despite its fundamental role, it is typically introduced as an abstract element of the theory with no explicit definition. Rather, physicists come to a working understanding of it through its use to calculate measurement outcome probabilities through the Born Rule. Tomographic methods can reconstruct the wavefunction from measured probabilities. In contrast, I present a method to directly measure the wavefunction so that its real and imaginary components appear straight on our measurement apparatus. I will also present new work extending this concept to mixed quantum states. This extension directly measures a little-known proposal by Dirac for a classical analog to a quantum operator. Furthermore, it reveals that our direct measurement is a rigorous example of a quasi-probability phase-space (i.e. x,p) distribution that is closely related to the Q, P, and Wigner functions. Our direct measurement method gives the quantum state a plain and general meaning in terms of a specific set of simple operations in the lab.

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