BEGIN:VCALENDAR
VERSION:2.0
PRODID:www.dresden-science-calendar.de
METHOD:PUBLISH
CALSCALE:GREGORIAN
X-MICROSOFT-CALSCALE:GREGORIAN
X-WR-TIMEZONE:Europe/Berlin
BEGIN:VTIMEZONE
TZID:Europe/Berlin
X-LIC-LOCATION:Europe/Berlin
BEGIN:DAYLIGHT
TZNAME:CEST
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
DTSTART:19810329T030000
RRULE:FREQ=YEARLY;INTERVAL=1;BYMONTH=3;BYDAY=-1SU
END:DAYLIGHT
BEGIN:STANDARD
TZNAME:CET
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
DTSTART:19961027T030000
RRULE:FREQ=YEARLY;INTERVAL=1;BYMONTH=10;BYDAY=-1SU
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
UID:DSC-12948
DTSTART;TZID=Europe/Berlin:20180326T163000
SEQUENCE:1522050538
TRANSP:OPAQUE
DTEND;TZID=Europe/Berlin:20180326T173000
URL:https://dresden-science-calendar.de/calendar/en/detail/12948
LOCATION:MPI-PKS\, Nöthnitzer Straße 3801187 Dresden
SUMMARY:Weitz: Colloquium: Lasing to Photon Bose-Einstein-Condensation Cros
 sover: Open versus Closed System Dynamics
CLASS:PUBLIC
DESCRIPTION:Speaker: Prof. Dr. Martin Weitz\nInstitute of Speaker: Universi
 tät Bonn\nTopics:\nPhysik\n Location:\n  Name: MPI-PKS (Seminarroom 1+2+3
 )\n  Street: Nöthnitzer Straße 38\n  City: 01187 Dresden\n  Phone: + 49 
 (0)351 871 0\n  Fax: \nDescription: Bose-Einstein condensation has been ob
 served with cold atomic gases\, exciton-polaritons\, and more recently wit
 h photons in a dye-solution filled optical microcavity. I will here descri
 be measurements of my Bonn group observing the transition between usual la
 sing dynamics and photon Bose-Einstein condensation. The photon Bose-Einst
 ein condensate is generated in a wavelength-sized optical cavity\, where t
 he small mirror spacing imprints a low-frequency cutoff and photons confin
 ed in the resonator thermalize to room temperature by absorption re-emissi
 on processes on the dye molecules. This allows for a particle-number conse
 rving thermalization\, with photons showing a thermodynamic phase transiti
 on to a macroscopically occupied ground state\, the Bose-Einstein condensa
 te. When the thermalization by absorption and re-emission is faster than t
 he photon loss rate in the cavity\, the photons accumulate at lower energy
  states above the cavity cutoff\, and the system finally thermalizes to a 
 Bose-Einstein condensate of photons. On the other hand\, for a small reabs
 orption with respect to the photon loss\, the state remains laser-like. I 
 will also report recent measurements of the heat capacity of the photon ga
 s\, which were performed under the conditions of the thermalization being 
 much faster than both photon loss and pumping. At the Bose-Einstein phase 
 transition\, the observed specific heat shows a cusp-like singularity\, as
  in the $\\lambda$-transition of liquid helium\, illustrating critical beh
 avior of the photon gas. In my talk\, I will begin with a general introduc
 tion and give an account of current work and future plans of the Bonn phot
 on gas experiment.
DTSTAMP:20260707T001202Z
CREATED:20170515T085242Z
LAST-MODIFIED:20180326T074858Z
END:VEVENT
END:VCALENDAR