Lene Hau

Career

In 1991, she joined the Rowland Institute for Science at Cambridge, Massachusetts as a scientific staff member, beginning to explore the possibilities of slow light and cold atoms. In 1999, at the age of 40, Hau accepted a two-year appointment as a postdoctoral fellow at Harvard University. Her formalized training is in theoretical physics, but her interest moved to experimental research in an effort to create a new form of matter known as a Bose–Einstein condensate. "Hau applied to the National Science Foundation for funds to make a batch of this condensate but was rejected on the grounds that she was a theorist for whom such experiments would be too difficult to do." Undeterred, she gained alternative funding and became one of the first handful of physicists to create such a condensate. In September 1999, she was appointed the Gordon Mckay Professor of Applied Physics and Professor of Physics at Harvard. She was also awarded tenure in 1999 and is now Mallinckrodt Professor of Physics and Applied Physics at Harvard. In 2001, she became the first person to stop light completely, using a Bose–Einstein condensate to achieve this. Since then, she has produced extensive research and new experimental work in electromagnetically induced transparency, various areas of quantum physics, photonics, and has contributed to the development of new quantum devices and novel nanoscale applications.

Qubit transfer

Hau and her associates at Harvard University "have demonstrated exquisite control over light and matter in several experiments, but her experiment with 2 condensates is one of the most compelling". In 2006, they successfully transferred a qubit from light to a matter wave and back into light, again using Bose–Einstein condensates. Details of the experiment are discussed in the February 8, 2007, publication of the journal Nature. The experiment relies on the way that, according to quantum mechanics, atoms may behave as waves as well as particles. This enables atoms to do some counterintuitive things, such as passing through two openings at once. Within a Bose–Einstein condensate a light pulse is compressed by a factor of 50 million, without losing any of the information stored within it. In this Bose–Einstein condensate, information encoded in a light pulse can be transferred to the atom waves. Because all the atoms move coherently, the information does not dissolve into random noise. The light drives some of the cloud's roughly 1.8 million sodium atoms to enter into "quantum superposition" states, with a lower-energy component that stays put and a higher-energy component that travels between the two clouds. A second 'control' laser then writes the pulse shape into the atom's wave function. When this control beam is turned off, and the light pulse disappears, the 'matter copy' remains. Prior to this, researchers could not readily control optical information during its journey, except to amplify the signal to avoid fading. This experiment by Hau and her colleagues marked the first successful manipulation of coherent optical information. The new study is "a beautiful demonstration", says Irina Novikova, a physicist at the College of William and Mary in Williamsburg, VA. Before this result, she says, light storage was measured in milliseconds. "Here it's fractional seconds. It's a really dramatic time."

Of its potential, Hau said, "While the matter is traveling between the two Bose–Einstein condensates, we can trap it, potentially for minutes, and reshape it – change it – in whatever way we want. This novel form of quantum control could also have applications in the developing fields of quantum information processing and quantum cryptography." Of the developmental implications, "This feat, the sharing around of quantum information in light-form and in not just one but two atom-forms, offers great encouragement to those who hope to develop quantum computers," said Jeremy Bloxham, dean of science in the Faculty of Arts and Sciences. Hau was awarded the George Ledlie Prize for this work, Harvard's Provost Steven Hyman noting "her work is path-breaking. Her research blurs the boundaries between basic and applied science, draws on the talent and people of two Schools and several departments, and provides a literally glowing example of how taking daring intellectual risks leads to profound rewards."

Cold atoms and nanoscale systems

In 2009, Hau and team laser-cooled clouds of one million rubidium atoms to just a fraction of a degree above absolute zero. They then launched this millimeter-long atomic cloud towards a suspended carbon nanotube, located some two centimeters away and charged to hundreds of volts. The results were published in 2010, heralding new interactions between cold atoms and nanoscale systems. They observed that most atoms passed by, but approximately 10 per million were inescapably attracted, causing them to dramatically accelerate both in movement and in temperature. "At this point, the speeding atoms separate into an electron and an ion rotating in parallel around the nanowire, completing each orbit in just a few trillionths of a second. The electron eventually gets sucked into the nanotube via quantum tunneling, causing its companion ion to shoot away – repelled by the strong charge of the 300-volt nanotube – at a speed of roughly 26 kilometers per second, or 59,000 miles per hour." Atoms can rapidly disintegrate, without having to collide with each other, in this experiment. The team notes that this effect is not produced by gravity in black holes, as calculated for black holes in space, but by the high electrical charge in the nanotube. The experiment combines nanotechnology with cold atoms to demonstrate a new type of high-resolution, single-atom, chip-integrated detector that may ultimately resolve fringes from the interference of matter waves. The scientists also foresee a range of single-atom, fundamental studies made possible by their setup.

Awards

• 1986-1989: Faculty of Sciences, University of Aarhus, Denmark – Research Fellowship
• 1988: Carlsberg Foundation, Denmark – Carlsberg Scholarship
• 1991: Rowland Institute – Gordon Mckay Professor of Applied Physics at Harvard and Principal Investigator for the Atom Cooling Group
• 2000: Top Danmark Foundation, Copenhagen – Year 2000 Award
• 2001: Samuel Friedman Foundation, University of California, Los Angeles – Samuel Friedman Rescue Award
• 2001: Honorary degree, Æreshåndværker Kjøbenhavns Håndværkerforening, in the presence of Her Majesty Queen Margrethe II of Denmark, Copenhagen
• 2001: Danish Natural Science Research Council – The Ole Rømer Medal
• 2001: Danish Physical Society – NKT Award
• 2001-2006: MacArthur Fellow 2001–2006 – Genius Grant
• 2004: American Association of Physics Teachers – Richtmyer Memorial Award
• 2008: George Ledlie Prize
• 2008: Rigmor and Carl Holst-Knudsen Award for Scientific Research
• 2010: Global Network of Danes Worldwide – "Årets Verdensdansker" (World Dane of the year) 2010 because she "emphatically and persistently has put Denmark on the world map".
• 2011: Carlsberg Foundation's Research Award from the Royal Danish Academy of Sciences and Letters

Guest lectures

• 2004: Leon Pape Memorial Lecture
• 2003: Slow Light for the Annals of Improbable Research (AIR)
• 2008: Capital Science Lecture at Carnegie Institution for Science
• 2010: H.C. Ørsted Lectureship
• 2018: Lise Meitner Distinguished Lecturer
• 2019: Dirac Medal and Lecture, the University of New South Wales

Honorary positions and memberships

• Royal Danish Academy of Sciences and Letters – honorary appointment
• 2008: Royal Swedish Academy of Sciences – foreign member
• 2009: American Academy of Arts and Sciences – member
• 2009: American Association for the Advancement of Science (AAAS) – fellow
• 2010: United States Department of Defense – National Security Science and Engineering Faculty Fellow
• 2011: Aarhus Universitet – honorary alum