
AsianScientist (Jan. 18, 2016) – Incredible advances in medicine, communications and astronomy based on light have prompted the United Nations to proclaim 2015 as the International Year of Light and Light-based Technologies.
This nugget of information was shared by Professor Serge Haroche, who is a co-recipient of the 2012 Nobel Prize in Physics. Haroche was visiting Singapore as an invited speaker of the Global Young Scientists Summit 2016 (GYSS@one-north), a five-day international boot camp for eminent scientists and technology leaders to mentor and inspire young researchers.
In his plenary lecture on Monday, 18 January, 2016, entitled “How questions about light have shaped our vision of the world and revolutionized our lives,” Haroche walked the audience through the history of light research, before urging science agencies to give scientists sufficient time and trust to perform their research.
Is light a particle or a wave?
“The first questions about light were answered by myths, religion and philosophy, but the first scientific answers came much later during the 17th century,” shared Haroche, who is currently the chair of quantum physics at the College de France Paris.
Scientific insight was hampered by the lack of adequate tools, he continued, explaining that quantitative observations on light phenomena only became possible in the 1600s with the invention of the first modern optical instruments: the microscope and telescope. Armed with these technological advances, scientists began to ask the first questions on light theory, such as whether light was made of particles or waves, and whether it is instantaneous or does it propagates at a finite velocity.
In one camp was Sir Isaac Newton, who held the theory that light was made up of discrete particles; in the other camp was Christiaan Huygens, who believed that light was due to the propagation of waves. Early experiments on light theory, such as Thomas Young’s light interference studies in the 1800s, supported Huygens’ wave theory over Newton’s particle theory.
But it was ultimately the contributions of hallowed scientists such as Max Planck and Albert Einstein that led to the modern appreciation of light’s dual nature—light can in fact exist both as a wave and a particle.
“I don’t want to go deeper into theory, but I want to stress that quantum physics has started to explain everything,” said Haroche. “It explains the structure of atoms and subatomic particles. It explains the basis for molecules and chemistry. It also explains macroscopic matter, which is made of billions and billions of atoms.”
But not everything can or will be explained by quantum physics, Haroche said; for one, it still cannot explain the existence of dark energy and dark matter.
A laser focus
The worlds of classical and quantum physics collided dramatically in the early 1900s when scientists accepted that light behaves both as a wave and a collection of particles known as photons.
But in those days, only thought experiments were possible—Erwin Schrödinger’s 1935 cat paradox imagined a cat in a box that could either be dead or alive, depending on whether a radioactive particle had decayed or not.
Using lasers, Haroche six decades later succeeded in turning Schrödinger’s thought experiment into reality. In 1996, he developed a photon trap that allowed the non-destructive observation of photons for the first time.
“Lasers can be used to manipulate the energy levels of atoms in an exquisitely precise way. We can use laser light to manipulate atoms individually, one by one,” said Haroche, describing a pivotal experiment that led to the 2012 Nobel Prize which he shared with American physicist David Jeffrey Wineland of the National Institute of Standards and Technology.
Motivated by “mere curiosity,” Haroche trapped several photons between two tiny superconducting mirrors, before passing highly activated atoms—known as Rydberg atoms—through the photon trap. By detecting changes to the Rydberg atoms from the other side, he could measure the quantum state of the photons in the trap.
“We are manipulating single atoms in a non-destructive way. Here we are just watching in a very subtle way the atoms, the photons,” he explained.
Curiosity-driven research
“Today, quantum technologies have provided us with a lot of innovations. Computers, lasers, atomic clocks, GPS and MRI scanners all require properties of quantum physics,” Haroche said. “All of what I have talked about today would have been impossible to imagine in the 1900s.”
These technologies are driven by both curiosity and serendipity, said Haroche, who cautioned against the pursuit of science with only translational value, and the need to provide almost-constant updates to funding agencies on one’s research progress.
“Technology emerges often in a very serendipitous way from blue sky research, and blue sky research needs two priceless ingredients: time and trust,” he said. “We need tens of years for these kinds of experiments, and we also need trust.”
Asian Scientist Magazine is a media partner of the GYSS@one-north 2016.
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Copyright: Asian Scientist Magazine.
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