Lene Vestergaard Hau

Den 18. februar 1999 vakte hun international opsigt, da det lykkedes hende og hendes forskerteam at sænke lysets hastighed drastisk. Det lykkedes at bremse lysets hastighed fra 300.000 kilometer/sekund til 17 meter/sekund. Det blev gjort ved at køle en lille cigarformet sky af natriumatomer ned til en temperatur få milliontedele grad varmere end det absolutte nulpunkt på ca. minus 273,16 grader.

I 2001 lykkedes det hende og hendes forskerteam at oplagre/stoppe en lyspuls, i en nedkølet sky af natriumatomer, ved hjælp at en koblingslaser. Når koblingslaseren lidt senere tændtes, genoptog den tidligere oplagrede lyspuls sin rejse ud af skyen.

Den nedkølede sky af natriumatomer, anvendt ved begge forsøg, er faktisk i en ny fasetilstandtilstand ud over de kendte; fast, flydende, gasform, plasma, (neutronstjerne?, kvarkstjerne?) - nemlig Bose-Einstein kondensat. Atomerne i Bose-Einstein kondensatet (BEC) er kvantefysisk sammenfiltret, hvilket bl.a. har den effekt, at hele skyen virker som et stort atom.

Se også

• Kvantemekanik

• Harvard University, Department of Physics: Lene Vestergaard Hau
• Rowland Institute for Science, RIS Members - Lene Vestergaard Hau
• Rowland Institute for Science, RIS Groups - Bose-Einstein Condensation, papers
• Chien Liu, Zachary Dutton, Cyrus H. Behroozi, Lene Vestergaard Hau. Observation of coherent optical information storage in an atomic medium using halted light pulses. Nature 409, 490-493 (25 January 2001), kopi hos Harvard
• BBC News: 18 January, 2001, Light stopped in its tracks Citat: "... And, astonishingly, if the coupling laser is turned off while the probe pulse is inside the gas cloud, the probe pulse stops dead in its tracks. If the coupling beam is then turned back on, the probe pulse emerges intact, just as if it had been waiting to resume its journey. The biggest impact of this work could be in the burgeoning field of quantum computing and quantum communication...."
• The American Institute of Physics Bulletin of Physics News, Number 415, February 18, 1999: Light has been slowed to a speed of 17 meters/second by passing it through a Bose- Einstein condensate (BEC) of sodium atoms
• Nature, 19 January 2001: Stop that light beam, I want to get off
• OE Reports, Number 185, May 1999, Behind the mass-media story: Bose-Einstein condensate slows light
• Quantum Physics, 14 Dec 2000, Many-particle entanglement with Bose--Einstein condensates
• Physics Web, 17 Mar 2000, Quantum leap for entanglement Citat: "...Entanglement is one of the most mysterious and fundamental properties of quantum mechanics. When two or more particles are "entangled", the wavefunction describing them cannot be factorized into a product of single-particle wavefunctions. This means that a measurement on one particle will immediately influence the state of the other particles in the entangled system. A group of physicists in the US has now "entangled" four particles for the first time (Nature 404 256)..."

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