The Kastler Brossel Laboratory
The Kastler Brossel Laboratory (LKB) is a joint research unit of the École Normale Supérieure, Sorbonne University, the Collège de France, and the French National Centre for Scientific Research (CNRS). It is one of the major players in the field of quantum physics, covering a wide range of topics from fundamental tests of quantum physics to their applications. Its expertise is internationally recognized, as evidenced by the three Nobel Prizes it has received in its 75-year history.
The laboratory’s activities have traditionally been linked to atomic physics and optics, with a particular focus on fundamental questions regarding light-matter interaction, quantum states of atoms and light, and precision spectroscopy. One of the significant developments over the past decades has been the cooling and trapping of atoms, opening up a rich field of study on quantum gases and liquids at the intersection of atomic physics and condensed matter physics.
Another strength of the laboratory is the study of the interaction between photons and atoms, with groundbreaking contributions in the fields of cavity quantum electrodynamics, quantum optics, and quantum information. While these concepts remain central to the LKB, the laboratory has diversified its research themes over the years. It now explores areas such as nanophotonics, optomechanics, the Casimir effect, imaging in biological and complex media, trapped ions, metrology, and tests of fundamental interactions. The LKB is also involved in several large-scale programs and international collaborations such as GBAR and LIGO-Virgo.
As a leader in quantum physics, the laboratory is heavily involved in the current development of quantum technologies. It plays a leading role in research on photonic qubits, quantum simulators based on cold atoms, quantum metrology, atomic and optomechanical sensors, optical cluster states for quantum computing, and quantum communications and networks.
Brief history
The laboratory was founded in 1951 by Alfred Kastler and Jean Brossel within the physics department of the École Normale Supérieure (ENS) on the Lhomond site. Initially named the “Laboratory of Hertzian Spectroscopy of ENS,” it adopted its current name in 1994 in tribute to its two founders, who were pioneers of modern physics in light-matter interaction after World War II. Thanks to their contributions Alfred Kastler received the Nobel Prize in 1966.
The laboratory experienced significant growth, and several teams moved in 1967 to the new university built on the Jussieu campus, now known as Sorbonne University (formerly Pierre and Marie Curie University). This move allowed the laboratory to undergo a significant evolution in its research themes and personnel, coinciding with the advent of lasers and the development of new research topics in the 1970s and 1980s. These changes led to the groundbreaking work of Claude Cohen-Tannoudji (Nobel Prize 1997) on the cooling and trapping of neutral atoms. Simultaneously, Serge Haroche’s work gave rise to the field of cavity quantum electrodynamics (Nobel Prize 2012).
Another major evolution was in 2014, when two of its research teams were elocated to the new Physics Institute of the Collège de France, actively contributing to the emergence of a new research center, particularly dedicated to quantum physics. This helped the LKB to extend its field to three geographical sites that brings benefits from rich and diverse environments.
