"Introduction to Weak Measurement"
In this talk I provide a pedagogical introduction to weak measurement in quantum mechanics. I will explain the Von Neumann model of measurement based on a quantum system coupled to a quantum meter (ancilla) which is then measured by an observer. I discuss the limits of ‘strong’ coupling, leading to a familiar projective measurement, and ‘weak’ coupling, described by a more general measurement operator which does not project the quantum system onto a single eigenstate. After establishing the effects of a single weak measurement on the system wavefunction, I will show how continuous weak measurement leads to a stochastic Schrödinger equation (SSE) for pure state evolution, conditioned on the measurement outcomes. If time allows, I will explain the connection between the SSE and the stochastic master equation, which illuminates a deep connection between the theory of continuous measurement and open quantum systems.
For students and postdocs only (no PIs!) - though anyone may join for beverages after 4:30 pm.