David DeMille | |
---|---|
Born | David DeMille |
Nationality | American |
Alma mater | University of Chicago (B.A.), University of California, Berkeley (Ph.D.) |
Awards | Francis M. Pipkin Award (2007) Norman F. Ramsey Prize (2024) |
Scientific career | |
Fields | Physics (atomic physics) |
Institutions | Amherst College (1997–1998) Yale University (1998–2020) University of Chicago (2020 – ) Argonne National Laboratory (2020 – ) [1] |
Doctoral advisor | Eugene Commins |
David P. DeMille is an American physicist and Professor of Physics at the University of Chicago. He is best known for his use of polar diatomic molecules to search for symmetry-violating effects within the molecules and as a means for manipulating the external properties of the molecules. [2]
His group was the first to accomplish laser cooling of a diatomic molecule, achieved in 2010 using strontium monofluoride (SrF). [3] [4] He is also known for his precise measurements in the ACME EDM Experiment [5] which constrain the upper limit of the electron electric dipole moment using a beam of thorium monoxide, conducted in collaboration with the groups of Gerald Gabrielse and John Doyle at Harvard. [6] DeMille is currently also leading the CeNTREX collaboration, an experiment to measure the nuclear Schiff moment of the thallium nucleus inside a thallium fluoride molecule. [7]
He was elected a fellow of the American Physical Society in 2005, [8] and was awarded the 2024 Norman F. Ramsey Prize in Atomic, Molecular and Optical Physics, and in Precision Tests of Fundamental Laws and Symmetries of the APS. [9]
T-symmetry or time reversal symmetry is the theoretical symmetry of physical laws under the transformation of time reversal,
Laser cooling includes a number of techniques where atoms, molecules, and small mechanical systems are cooled with laser light. The directed energy of lasers is often associated with heating materials, e.g. laser cutting, so it can be counterintuitive that laser cooling often results in sample temperatures approaching absolute zero. Laser cooling relies on the change in momentum when an object, such as an atom, absorbs and re-emits a photon. For an ensemble of particles, their thermodynamic temperature is proportional to the variance in their velocity. That is, more homogeneous velocities among particles corresponds to a lower temperature. Laser cooling techniques combine atomic spectroscopy with the aforementioned mechanical effect of light to compress the velocity distribution of an ensemble of particles, thereby cooling the particles.
Supersymmetry is a theoretical framework in physics that suggests the existence of a symmetry between particles with integer spin (bosons) and particles with half-integer spin (fermions). It proposes that for every known particle, there exists a partner particle with different spin properties. There have been multiple experiments on supersymmetry that have failed to provide evidence that it exists in nature. If evidence is found, supersymmetry could help explain certain phenomena, such as the nature of dark matter and the hierarchy problem in particle physics.
In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end.
In atomic physics, hyperfine structure is defined by small shifts in otherwise degenerate energy levels and the resulting splittings in those energy levels of atoms, molecules, and ions, due to electromagnetic multipole interaction between the nucleus and electron clouds.
Molecular physics is the study of the physical properties of molecules and molecular dynamics. The field overlaps significantly with physical chemistry, chemical physics, and quantum chemistry. It is often considered as a sub-field of atomic, molecular, and optical physics. Research groups studying molecular physics are typically designated as one of these other fields. Molecular physics addresses phenomena due to both molecular structure and individual atomic processes within molecules. Like atomic physics, it relies on a combination of classical and quantum mechanics to describe interactions between electromagnetic radiation and matter. Experiments in the field often rely heavily on techniques borrowed from atomic physics, such as spectroscopy and scattering.
In physics, tunnel ionization is a process in which electrons in an atom tunnel through the potential barrier and escape from the atom. In an intense electric field, the potential barrier of an atom (molecule) is distorted drastically. Therefore, as the length of the barrier that electrons have to pass decreases, the electrons can escape from the atom's potential more easily. Tunneling ionization is a quantum mechanical phenomenon, since in the classical picture an electron does not have sufficient energy to overcome the potential barrier of the atom.
Doppler cooling is a mechanism that can be used to trap and slow the motion of atoms to cool a substance. The term is sometimes used synonymously with laser cooling, though laser cooling includes other techniques.
The electron electric dipole momentde is an intrinsic property of an electron such that the potential energy is linearly related to the strength of the electric field:
Quantum electrodynamics (QED), a relativistic quantum field theory of electrodynamics, is among the most stringently tested theories in physics. The most precise and specific tests of QED consist of measurements of the electromagnetic fine-structure constant, α, in various physical systems. Checking the consistency of such measurements tests the theory.
Gerald Gabrielse is an American physicist. He is the Board of Trustees Professor of Physics and director of the Center for Fundamental Physics at Northwestern University, and Emeritus George Vasmer Leverett Professor of Physics at Harvard University. He is primarily known for his experiments trapping and investigating antimatter, measuring the electron g-factor, and measuring the electron electric dipole moment. He has been described as "a leader in super-precise measurements of fundamental particles and the study of anti-matter."
The neutron electric dipole moment (nEDM), denoted dn, is a measure for the distribution of positive and negative charge inside the neutron. A nonzero electric dipole moment can only exist if the centers of the negative and positive charge distribution inside the particle do not coincide. So far, no neutron EDM has been found. The current best measured limit for dn is (0.0±1.1)×10−26 e⋅cm.
CryoEDM is a particle physics experiment aiming to measure the electric dipole moment (EDM) of the neutron to a precision of ~10−28ecm. The name is an abbreviation of cryogenic neutron EDM experiment. The previous name nEDM is also sometimes used, but should be avoided where there may be ambiguity. The project follows the Sussex/RAL/ILL nEDM experiment, which set the current best upper limit of 2.9×10−26ecm. To reach the improved sensitivity, cryoEDM uses a new source of ultracold neutrons (UCN), which works by scattering cold neutrons in superfluid helium.
High-precision experiments could reveal small previously unseen differences between the behavior of matter and antimatter. This prospect is appealing to physicists because it may show that nature is not Lorentz symmetric.
In physics a non-neutral plasma is a plasma whose net charge creates an electric field large enough to play an important or even dominant role in the plasma dynamics. The simplest non-neutral plasmas are plasmas consisting of a single charge species. Examples of single species non-neutral plasmas that have been created in laboratory experiments are plasmas consisting entirely of electrons, pure ion plasmas, positron plasmas, and antiproton plasmas.
Thorium monoxide, is the binary oxide of thorium having chemical formula ThO. The covalent bond in this diatomic molecule is highly polar. The effective electric field between the two atoms has been calculated to be about 80 gigavolts per centimeter, one of the largest known internal effective electric fields.
Yannis K. Semertzidis is a physicist exploring axions as a dark matter candidate, precision physics in storage rings including muon g-2 and proton electric dipole moment (pEDM). The axion and the pEDM are intimately connected through the strong CP problem. Furthermore, if the pEDM is found to be non-zero, it can help resolve the matter anti-matter asymmetry mystery of our universe. During his research career, he held a number of positions in the Department of Physics in Brookhaven National Laboratory, including initiator and co-spokesperson of the Storage Ring Electric Dipole Moment Collaboration. He is the founding director of the Institute for Basic Science (IBS) Center for Axion and Precision Physics Research, is a professor in the Physics Department of KAIST, and a Fellow of the American Physical Society.
The rotating wall technique is a method used to compress a single-component plasma confined in an electromagnetic trap. It is one of many scientific and technological applications that rely on storing charged particles in vacuum. This technique has found extensive use in improving the quality of these traps and in tailoring of both positron and antiproton plasmas for a variety of end uses.
Tanya Zelevinsky is a professor of physics at Columbia University. Her research focuses on high-precision spectroscopy of cold molecules for fundamental physics measurements, including molecular lattice clocks, ultracold molecule photodissociation, as well as cooling and quantum state manipulation techniques for diatomic molecules with the goal of testing the Standard Model of particle physics. Zelevinsky graduated from MIT in 1999 and received her Ph.D. from Harvard University in 2004 with Gerald Gabrielse as her thesis advisor. Subsequently, she worked as a post-doctoral research associate at the Joint Institute for Laboratory Astrophysics (JILA) with Jun Ye on atomic lattice clocks. She joined Columbia University as an associate professor of physics in 2008. Professor Zelevinsky became a Fellow of the American Physical Society in 2018 and received the Francis M. Pipkin Award in 2019.
John Morrissey Doyle is an American physicist working in the field of Atomic, Molecular, and Optical (AMO) physics and Precision Particle Physics. He is the Henry B. Silsbee Professor of Physics, Director of the Japanese Undergraduate Research Exchange Program (JUREP), Co-Director of the Harvard Quantum Initiative as well as Co-director of the Ph.D. Program in Quantum Science and Engineering at Harvard University.