- Person
- Serge Haroche
- Lived
- b. 1944
- Field
- Quantum physics
- From
- French
The story
Serge Haroche was born in Casablanca in 1944 into a Jewish family of Sephardic and Ashkenazi origin; his grandparents taught in the schools of the Alliance Israélite Universelle, and his mother’s family were Russian Jewish physicians. The family moved to France in 1956. Haroche studied at the École Normale Supérieure in Paris under Claude Cohen-Tannoudji and spent his career there and at the Collège de France, studying how atoms and light interact.
Measuring light normally destroys it: a camera or a photodetector works by absorbing photons. That made it impossible to watch a single particle of light over time, and many of the strangest predictions of quantum mechanics remained thought experiments. Haroche and his colleagues Jean-Michel Raimond and Michel Brune spent years building an apparatus to get around this. At its heart are two superconducting mirrors about three centimetres apart, cooled to just above absolute zero, which are so reflective that a microwave photon can bounce between them for more than a tenth of a second.
To look at the photon without absorbing it, the team sent Rydberg atoms, giant atoms about a thousand times larger than normal, through the cavity one at a time. Each atom left the photon in place but came out with its quantum state slightly shifted, revealing whether a photon was there. In 2007 they reported following single photons in this way, seeing them appear and vanish in real time, and they learned to count the photons in the cavity, in the Nobel committee’s words, as a child counts marbles in a bowl. They also created superpositions of light, nicknamed Schrödinger cat states, and watched them decay into ordinary classical states, a process called decoherence that they had first observed in 1996.
These techniques showed that single quantum systems can be measured and manipulated while keeping their quantum properties, exactly what quantum computers need. The ideas of cavity quantum electrodynamics were carried over to superconducting circuits, which now form the basis of many quantum processors, and the study of decoherence guides engineers trying to protect fragile quantum bits. Haroche shared the 2012 Nobel Prize in Physics with David J. Wineland for this work.
Why it matters
Haroche’s methods for observing and controlling single quantum particles laid groundwork for today’s quantum computers and quantum sensors.
About Serge Haroche
Casablanca-born French physicist who trapped single particles of light in a box of mirrors and watched them without destroying them, groundwork for today’s quantum computers. Nobel Prize 2012.
Sources
- The Nobel Prize in Physics 2012, Popular information NobelPrize.org
- Serge Haroche, Biographical NobelPrize.org
- Serge Haroche Wikipedia
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