Born in 1900 in Breslau (today Wrocław in Poland), Fritz London studied philosophy before choosing science. After getting a PhD in Munich in 1921, he understood what bonds two hydrogen atoms in a H2 molecule. This work he did with Walter Heitler in Zürich was the starting point for the understanding of chemical bonding. Then he joined Erwin Schrödinger in Berlin but had to leave in 1933 because of the rise of anti-Semitism in Nazi Germany. After a stay in Oxford where he worked on superconductivity with his brother Heinz, he sought refuge at the Institut Henri Poincaré (Paris) in 1936, thanks to a group of intellectuals linked to the Popular Front (Jacques Hadamard, Paul Langevin, Jean Perrin, Frédéric Joliot and Edmond Bauer).
It is at that time, in 1938, that he explained that the superfluidity in liquid helium was a manifestation of Bose-Einstein condensation, a purely quantum phenomenon that could be seen for the first time on a macroscopic scale. This work followed a series of articles about superconductivity that could finally be understood as a superfluidity of charged particles (electron pairs in the case of superconducting metals).
At the beginning of World War II (September 1939), he left France and joined Duke University (USA) where Paul Gross had offered him a professorship in the Chemistry Department and where he felt more comfortable with his wife, the painter Edith London. Einstein wanted the Nobel Prize to be awarded to Fritz London, but London died prematurely in 1954.
The “London equations” prove that a magnetic field only penetrates the surface of a superconducting material because the absence of collisions between the electrons enables the electricity to be transported with no loss. The “London penetration depth” defines the maximum penetration length of a magnetic field in a superconductor.
According to John Bardeen, one of the creators of the BCS theory of superconductivity, it was Fritz London who made quantum physics take a huge step from the microscopic subatomic scale to the macroscopic world of matter on a human scale.
Since London’s death, the “Fritz London memorial prize” rewards the best works in Low Temperature Physics of Condensed Matter. John Bardeen gave part of his second Nobel Prize to help financing the London Prize.
