Jess Riedel (NTT Research - Physics & Informatics Lab ): Wavefunction branches
Channel: Centrum Fizyki Teoretycznej PAN
Date: 2021-04-08

Jess Riedel (NTT Research - Physics & Informatics Lab )
 Wavefunction branches.
In the past, quasiclassical branches in the wavefunction were described through carefully choreographed and enthusiastic handwaving. Within the many-body lattice context, we now have two mathematically precise guiding principles: *redundantly recorded observables*, a generalization of quantum Darwinism concepts that avoids a-priori preferred subsystems, and *N-point non-interference*, a formalization of effective wavefunction collapse relevant to numerical simulations. These conditions are respectively too strong and too weak in a particular sense, but they clearly illuminate and roughly bound the goal of identifying a mathematically precise definition of wavefunction branches. I argue that achieving this goal (1) would allow us to ask deep questions about quantum foundations that cannot otherwise be clearly formulated, (2) would have (maybe modest) real-world applications, and (3) is the single most promising approach to making progress on the measurement problem. The question of how to define branches is simultaneously neglected, tractable, and profound. 
CTP Quantum Information Days (online), 22-24 February 2021.
Center for Theoretical Physics PAS (Warsaw, Poland)