Mark Beck, professor of physics at Reed College, will visit campus to discuss new quantum measurement schemes.
"The standard description of a measurement in quantum mechanics is that of a strong (or von Neumann) measurement. Such a measurement yields the eigenvalue of a measurement operator, and the state of the system 'collapses' into the eigenstate corresponding to the measured eigenvalue. Information about the original state is obtained, but that state is maximally disturbed (the resulting state retains no information about the original state). In the past twenty years or so, however, new quantum measurement schemes have been developed. In a weak measurement one obtains information about a quantum system, while only weakly disturbing its state. A protective measurement is a special case of a weak measurement, in which an explicit state-protection operation is implemented. Information about the quantum system is obtained, while the state of that system is unchanged. Because the state is unchanged, the measurement may be repeated many times on the same system, decreasing the uncertainty. In this way protective measurements may outperform strong measurements, in the sense that they can yield a lower measurement uncertainty. In this presentation I will describe the theory of strong, weak and protective measurements. I will also describe the experiments we have carried out to perform protective measurements on single-photon level fields."
Join us on Tuesday, Apr. 28, (note the date and time change) for this exciting presentation from Beck. Lunch will be available in Hayes 216 from 10:45 a.m. to 11:15 p.m., and the presentation will begin in Hayes 211/213 at 11:10 p.m. We hope to see you there!