PIRSA:14030110

Seeing is Believing: Direct Observation of a General Quantum State

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}}
          }

Jeff Lundeen

University of Ottawa

Talk number
PIRSA:14030110
Collection
Talk Type
Subject
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.