Nikolas Blomberg

Nikolas Blomberg

American physicist of Dutch origin. Winner of the Nobel Prize in Physics for 1981 (together with Arthur Shavlov).
Date of Birth: 11.03.1920
Country: Netherlands

Biography of Nicholas Blombergen

Nicholas Blombergen was an American physicist of Dutch origin. He was awarded the Nobel Prize in Physics in 1981, along with Arthur Schawlow. Blombergen was born in Dordrecht, Netherlands, and was the second of six children to Oke Blombergen and Sofia Maria (nee Quint) Blombergen. His father was a chemical engineer and worked for a fertilizer company, while his mother, who had a doctoral degree in mathematical physics, dedicated herself to caring for the family.

Blombergen grew up in a conservative, disciplined, and intellectual atmosphere. He loved reading and engaged in various outdoor activities such as swimming, sailing, and ice skating, which were encouraged by his family. After the family relocated to Bilthoven, a suburb of Utrecht, Blombergen attended primary school and later enrolled in the municipal gymnasium in Utrecht. The focus of his education was on humanities, as the students were being prepared for university. Most of his teachers held doctoral degrees. It was only in the last years of his education that his inclination towards natural sciences became apparent as he started studying the basics of physics and chemistry.

In 1938, Blombergen enrolled in Utrecht University to study physics. He later wrote, "The choice of physics was probably due to the fact that this subject seemed to be the most difficult to me." However, with the occupation of the Netherlands by Germany in 1940, many faculty members were dismissed or captured by the Gestapo. Nevertheless, Blombergen obtained the equivalent of a master's degree in 1943, just before the university was closed by the Nazis. He went into hiding for the next two years. By the end of the war, Europe was devastated, so Blombergen had to turn to American educational institutions for further studies. He was admitted to the graduate program at Harvard University in 1945 and continued his studies there, attending lectures by leading physicists such as Julius S. Schwinger and John X. Van Vleck.

Just six weeks before Blombergen's arrival in the United States, Edward M. Purcell and two of his colleagues discovered nuclear magnetic resonance (NMR) – the absorption and emission of high-frequency electromagnetic energy by atomic nuclei related to their nuclear spin. Nuclei behave like spinning tops. Since they are positively charged, their motion is equivalent to an electric current, which generates a magnetic field similar to the field produced by a current in the coils of an electromagnet. Nuclear magnetism, like any magnetism, has magnitude and direction and interacts with external electromagnetic fields.

As Purcell's graduate student, Blombergen helped develop the first NMR devices and, together with Purcell and R. V. Pound, published an important paper in 1948 on the relaxation effect in NMR – the return of nuclear magnetic orientation to its previous state after excitation by electromagnetic fields from an external source. This return is influenced by the surrounding structure and depends on its details. Many of these materials were included in Blombergen's doctoral dissertation, which he presented at Leiden University in the same year. He then moved to Leiden in 1947 and began working at the laboratory named after the Dutch physicist Heike Kamerlingh Onnes.

Returning to the United States in 1949, Blombergen was elected a member of the prestigious Harvard Society of Fellows. He became an adjunct professor there in 1951, a full professor in 1957, a professor of physics in 1974, and a university professor in 1980.

In 1953, Charles H. Townes, along with two colleagues, demonstrated a maser (an acronym for "microwave amplification by stimulated emission of radiation") at Columbia University, which produces intense, narrow, monochromatic microwave beams. Stimulated (induced) emission was predicted by Albert Einstein in 1917 based on the quantum theory and Niels Bohr's atomic model, which postulates that negatively charged electrons orbit a positively charged dense central nucleus. The electron's motion is limited to certain orbits (or energy levels), and they can transition from a lower to a higher level by absorbing electromagnetic radiation. Max Planck showed that this radiation consists of discrete portions, now called photons, and that its frequency is proportional to the energy of the photon. The absorbed photon has an energy equal to the difference between two characteristic energy levels of the atom. The excited electron then quickly returns to a lower level, emitting a photon with corresponding energy (and frequency), equal to the difference between the levels. Typically, photons are emitted at random times and are completely uncorrelated in phase. Einstein showed that if atoms (or molecules, which also have energy levels but are more complex than atoms) could be excited to a particular energy level and kept there, the emission of appropriate frequency photons would cause their simultaneous transition to a lower level. The frequency and energy of the photons must correspond to the difference between the two energy levels. As a result, a cascade of photons, with the same frequency and phase, would be emitted simultaneously, generating powerful coherent (all in phase) radiation. Since a relatively small electromagnetic signal induces a relatively large signal of the same frequency at the output, amplification occurs due to induced emission. Townes used gaseous ammonia with two special energy levels, the difference of which corresponded to radio frequency photons, in his maser. When Blombergen wrote his paper on magnetic resonance in 1956, he proposed a three-level scheme for masers, which allowed for the use of solid materials such as crystals. According to this scheme, the crystal, excited by radiation of the appropriate frequency, transitions to the highest of the three specific energy levels. As a result of natural decay from the excited state, a transition to an intermediate level occurs, serving as a source of induced emission. Then, emission with a frequency corresponding to the difference between the two lowest levels causes the emission of the desired radiation. Arthur L. Schawlow later referred to Blombergen's scheme as the first practically useful maser.

The first device to produce stimulated (induced) emission of visible light was built in 1960 by American physicist Theodore Maiman and was named the "laser" (an acronym for "light amplification by stimulated emission of radiation"). In the same year, Schawlow and other physicists also built lasers. During the same period, both masers and lasers were independently created by Nikolay Basov and Alexander Prokhorov. In 1965, Arno A. Penzias and Robert W. Wilson used a solid-state maser based on a ruby crystal to detect cosmic microwave background radiation, the remains of the hypothetical "big bang" that gave birth to our Universe.

Blombergen is known as one of the creators of nonlinear optics, a general theory of the interaction of electromagnetic radiation with matter that is broader than the one formulated by James Clerk Maxwell in the 19th century. According to Maxwell's theory, the effect of visible light or any other form of electromagnetic radiation on matter is directly proportional to the intensity of the radiation. In 1962, Blombergen and three colleagues published a general theory of nonlinear optics, which he subsequently expanded. He made significant contributions to the development of lasers, showing that due to the laws of nonlinear optics, harmonics, multiples of the fundamental frequency, similar to overtones in sound, can appear in a laser, resulting in the emission of higher-frequency energy beams. By describing the hypothetical interaction of three laser beams that produce a fourth beam, the frequency of which can be precisely controlled, Blombergen laid the theoretical groundwork for the development of tunable lasers. Using tunable lasers, other researchers, including Schawlow, developed sophisticated laser spectroscopy techniques, providing new detailed information about the structure of atoms and molecules. In laser spectroscopy, laser beams excite atoms, bringing them to higher energy levels compared to the lowest (ground) state. By observing which frequencies are preferentially absorbed or emitted, spectroscopists can determine the characteristic energy levels, or the structure, of the studied material. The precise knowledge of the beam's frequency, provided by the monochromatic (single-frequency) nature of laser light, as well as the ability to precisely tune the frequency to different energy levels, allows for a more in-depth analysis.

"For his contributions to the development of laser spectroscopy," Blombergen and Schawlow shared half of the 1981 Nobel Prize in Physics. The other half was awarded to Kai Siegbahn for electron spectroscopy using X-rays. In his Nobel lecture, Blombergen pointed out some applications of nonlinear optical processes, including the development of optical communication systems, temporal and linear metrology, and information gathering.

At a physics conference in the Netherlands in 1948, Blombergen met Hubertina Deliana Brink, a native of Indonesia who was studying medicine. She followed him to the United States the following year on a student exchange program, and Blombergen proposed to her on her first day of arrival. They married in 1950 and have a son and two daughters. He became a U.S. citizen in 1958. Described as a "good old Dutch gentleman" by one of his colleagues, Blombergen enjoys playing tennis, taking walks, and skiing. The family resides in Lexington, Massachusetts.

In addition to the Nobel Prize, Blombergen received the Oliver E. Buckley Prize from the American Physical Society (1958), the Morris E. Liebmann Memorial Prize from the Institute of Radio Engineers (1959), the Stuart Ballantine Medal from the Franklin Institute (1961), the National Medal for Scientific Achievement from the National Science Foundation (1974), and the Frederic Ives Medal from the Optical Society of America (1979). He is a member of the American Academy of Arts and Sciences, the National Academy of Sciences, and the Royal Netherlands Academy of Arts and Sciences.