BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Joshua Foo (Stevens Institute of Technology) DTSTART:20230418T070000Z DTEND:20230418T090000Z DTSTAMP:20260417T072056Z UID:3cqfs/3 DESCRIPTION:Title: Te lefilters\, telemirrors\, and causality\nby Joshua Foo (Stevens Instit ute of Technology) as part of Tricontinental Quantum Fundamentals Seminar\ n\n\nAbstract\nMode-selective interactions are ubiquitous in quantum optic s and interacting quantum field theories. Such unitaries take as input a m ulti-mode field but uniquely affect a single mode\, compared with those or thogonal to it. Despite their wide application in theoretical and experime ntal physics\, the temporal dimension of such interactions are typically i gnored.\n\nHere\, I demonstrate how the naïve treatment of a mode-selecti ve unitaries leads to the possibility of acausal signalling\, due to the t acit assumption that certain kinds of idealised measurements of quantum fi elds can be made. I achieve this by introducing new theoretical models for mode-selective mirrors using continuous-variable teleportation\, which is able to unveil the temporal aspects of the mode propagation.\n\nThe main result is that mode-selective operations must generally enact a fundamenta l time-delay on input modes that are delocalised in time. This result reso lves Sorkin's long-standing "impossible measurement" problem in relativist ic quantum field theory\, and thus has significant implications for experi mental quantum optics and those working in quantum causality and field the ory.\n\nTalk not recorded\n LOCATION:https://researchseminars.org/talk/3cqfs/3/ END:VEVENT END:VCALENDAR