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Ultra-cold Atoms
Ultracold atoms are atoms that are maintained at temperatures close to 0 kelvin (absolute zero), typically below several tens of microkelvin (µK). At these temperatures the atom's quantum-mechanical properties become important. To reach such low temperatures, a combination of several techniques typically has to be used. First, atoms are usually trapped and pre-cooled via laser cooling in a magneto-optical trap. To reach the lowest possible temperature, further cooling is performed using evaporative cooling in a magnetic or optical trap. Several Nobel prizes in physics are related to the development of the techniques to manipulate quantum properties of individual atoms (e.g. 1995-1997, 2001, 2005, 2012, 2017). Experiments with ultracold atoms study a variety of phenomena, including quantum phase transitions, Bose–Einstein condensation (BEC), bosonic superfluidity, quantum magnetism, many-body spin dynamics, Efimov states, Bardeen–Cooper–Schrieffer (BCS) superfluidity and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelvin
The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and physicist William Thomson, 1st Baron Kelvin (1824–1907). The Kelvin scale is an absolute thermodynamic temperature scale, meaning it uses absolute zero as its null (zero) point. Historically, the Kelvin scale was developed by shifting the starting point of the much-older Celsius scale down from the melting point of water to absolute zero, and its increments still closely approximate the historic definition of a degree Celsius, but since 2019 the scale has been defined by fixing the Boltzmann constant to be exactly . Hence, one kelvin is equal to a change in the thermodynamic temperature that results in a change of thermal energy by . The temperature in degree Celsius is now defined as the temperature in kelvins minus 273.15, meaning t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubbard Model
The Hubbard model is an approximate model used to describe the transition between conducting and insulating systems. It is particularly useful in solid-state physics. The model is named for John Hubbard. The Hubbard model states that each electron experiences competing forces: one pushes it to tunnel to neighboring atoms, while the other pushes it away from its neighbors. Its Hamiltonian thus has two terms: a kinetic term allowing for tunneling ("hopping") of particles between lattice sites and a potential term reflecting on-site interaction. The particles can either be fermions, as in Hubbard's original work, or bosons, in which case the model is referred to as the "Bose–Hubbard model". The Hubbard model is a useful approximation for particles in a periodic potential at sufficiently low temperatures, where all the particles may be assumed to be in the lowest Bloch band, and long-range interactions between the particles can be ignored. If interactions between particles at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold Atom Laboratory
The Cold Atom Laboratory (CAL) is an experimental instrument on board the ISS, which launched in 2018. It creates an extremely cold microgravity environment in order to study behaviour of atoms in these conditions. Timeline The CAL was developed at JPL in Pasadena, California. It was originally scheduled for launch to the International Space Station (ISS) in June 2017. It was then delayed until a scheduled launch on a SpaceX CRS-12 rocket in August 2017. It was finally launched on May 21, 2018. The initial mission had a duration of 12 months with up to five years of extended operation. In January 2020 it underwent hardware upgrades, which were carried out over an eight-day period by astronauts Christina Koch and Jessica Meir under the supervision of ground controllers. The upgrade included an atom interferometer which can be used to study the equivalence principle. In July 2021, another upgrade by astronaut Megan McArthur gave CAL the ability to work with ultracold potassium a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carl Wieman
Carl Edwin Wieman (born March 26, 1951) is an American physicist and educationist at Stanford University, and currently the A.D White Professor at Large at Cornell University. In 1995, while at the University of Colorado Boulder, he and Eric Allin Cornell produced the first true Bose–Einstein condensate (BEC) and, in 2001, they and Wolfgang Ketterle (for further BEC studies) were awarded the Nobel Prize in Physics. Wieman currently holds a joint appointment as Professor of Physics and Professor in the Stanford Graduate School of Education, as well as the DRC Professor in the Stanford University School of Engineering. In 2020, Wieman was awarded the Yidan Prize in Education Research for "his contribution in developing new techniques and tools in STEM education.citation Biography Wieman was born in Corvallis, Oregon to N. Orr Wieman and Alison Marjorie Fry in the United States and graduated from Corvallis High School. His paternal grandfather Henry Nelson Wieman was a religi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wolfgang Ketterle
Wolfgang Ketterle (; born 21 October 1957) is a German physicist and professor of physics at the Massachusetts Institute of Technology (MIT). His research has focused on experiments that trap and cool atoms to temperatures close to absolute zero, and he led one of the first groups to realize Bose–Einstein condensation in these systems in 1995. For this achievement, as well as early fundamental studies of condensates, he was awarded the Nobel Prize in Physics in 2001, together with Eric Allin Cornell and Carl Wieman. Biography Ketterle was born in Heidelberg, Baden-Württemberg, and attended school in Eppelheim and Heidelberg. In 1976 he entered the University of Heidelberg, before transferring to the Technical University of Munich two years later, where he gained the equivalent of his master's diploma in 1982. In 1986 he earned a PhD in experimental molecular spectroscopy under the supervision of Herbert Walther and Hartmut Figger at the Max Planck Institute for Quantum Optics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eric Cornell
Eric Allin Cornell (born December 19, 1961) is an American physicist who, along with Carl E. Wieman, was able to synthesize the first Bose–Einstein condensate in 1995. For their efforts, Cornell, Wieman, and Wolfgang Ketterle shared the Nobel Prize in Physics in 2001. Biography Cornell was born in Palo Alto, California, where his parents were completing graduate degrees at nearby Stanford University. Two years later he moved to Cambridge, Massachusetts, where his father was a professor of civil engineering at MIT. Here he grew up with his younger brother and sister, with yearlong intermezzos in Berkeley, California, and Lisbon, Portugal, where his father spent sabbatical years. In Cambridge he attended Cambridge Rindge and Latin, Cambridge Rindge and Latin School. The year before his graduation he moved back to California with his mother and finished high school at San Francisco's Lowell High School (San Francisco), Lowell High School, a local magnet school for academically ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
State Of Matter
In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Many intermediate states are known to exist, such as liquid crystal, and some states only exist under extreme conditions, such as Bose–Einstein condensates (in extreme cold), neutron-degenerate matter (in extreme density), and quark–gluon plasma (at extremely high energy). For a complete list of all exotic states of matter, see the list of states of matter. Historically, the distinction is made based on qualitative differences in properties. Matter in the solid state maintains a fixed volume (assuming no change in temperature or air pressure) and shape, with component particles ( atoms, molecules or ions) close together and fixed into place. Matter in the liquid state maintains a fixed volume (assuming no change in temperature or air pressure), but has a variable shape that adapts to fit its contain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evaporative Cooling (atomic Physics)
Evaporative cooling is an atomic physics technique to achieve high phase space densities which optical cooling techniques alone typically can not reach. Atoms trapped in optical or magnetic traps can be evaporatively cooled via two primary mechanisms, usually specific to the type of trap in question: in magnetic traps, radiofrequency (RF) fields are used to selectively drive warm atoms from the trap by inducing transitions between trapping and non-trapping spin states; or, in optical traps, the depth of the trap itself is gradually decreased, allowing the most energetic atoms in the trap to escape over the edges of the optical barrier. In the case of a Maxwell-Boltzmann distribution for the velocities of the atoms in the trap, as in the figure at right, these atoms which escape/are driven out of the trap lie in the highest velocity tail of the distribution, meaning that their kinetic energy (and therefore temperature) is much higher than the average for the trap. The net result is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William D
William is a male given name of Germanic origin.Hanks, Hardcastle and Hodges, ''Oxford Dictionary of First Names'', Oxford University Press, 2nd edition, , p. 276. It became very popular in the English language after the Norman conquest of England in 1066,All Things William"Meaning & Origin of the Name"/ref> and remained so throughout the Middle Ages and into the modern era. It is sometimes abbreviated "Wm." Shortened familiar versions in English include Will, Wills, Willy, Willie, Bill, and Billy. A common Irish form is Liam. Scottish diminutives include Wull, Willie or Wullie (as in Oor Wullie or the play ''Douglas''). Female forms are Willa, Willemina, Wilma and Wilhelmina. Etymology William is related to the given name ''Wilhelm'' (cf. Proto-Germanic ᚹᛁᛚᛃᚨᚺᛖᛚᛗᚨᛉ, ''*Wiljahelmaz'' > German ''Wilhelm'' and Old Norse ᚢᛁᛚᛋᛅᚼᛅᛚᛘᛅᛋ, ''Vilhjálmr''). By regular sound changes, the native, inherited English form of the name should b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Claude Cohen-Tannoudji
Claude Cohen-Tannoudji (; born 1 April 1933) is a French physicist. He shared the 1997 Nobel Prize in Physics with Steven Chu and William Daniel Phillips for research in methods of laser cooling and trapping atoms. Currently he is still an active researcher, working at the École normale supérieure (Paris). Early life Cohen-Tannoudji was born in Constantine, French Algeria, to Algerian Jewish parents Abraham Cohen-Tannoudji and Sarah Sebbah. When describing his origins Cohen-Tannoudji said: "My family, originally from Tangier, settled in Tunisia and then in Algeria in the 16th century after having fled Spain during the Inquisition. In fact, our name, Cohen-Tannoudji, means simply the Cohen family from Tangiers. The Algerian Jews obtained the French citizenship in 1870 after Algeria became a French colony in 1830." After finishing secondary school in Algiers in 1953, Cohen-Tannoudji left for Paris to attend the École Normale Supérieure. His professors included Henri Cartan, L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steven Chu
Steven Chu''Chu, Steven'' was elected a fellow of the American Physical Society in 1986 for his contributions in atomic physics and laser spectroscopy, including the first observation of parity non-conservation in atoms, excitation and precision spectroscopy of positronium, and the optical confinement and cooling of atoms. (born February 28, 1948) is an American Experimental physics, physicist and former government official. He is a Nobel laureate and was the 12th United States Secretary of Energy. He is currently the William R. Kenan Jr. Professor of Physics and Professor of Molecular and Cellular Physiology at Stanford University. He is known for his research at the University of California, Berkel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeeman Slower
A Zeeman slower is a scientific apparatus that is commonly used in atomic physics to slow and cool a beam of hot atoms to speeds of several meters per second and temperatures below a kelvin. The Gas-phase atoms used in atomic physics are often generated in an oven by heating a solid or liquid atomic sample to temperatures where the vapor pressure is high enough that there are a substantial number of atoms in the gas phase. These atoms effuse out of a hole in the oven with average speeds on the order of hundreds of m/s and large velocity distributions (due to their high temperature). The Zeeman slower is attached close to where the hot atoms exit the oven and is used to slow them to less than 10 m/s (slowing) with a very small velocity spread (cooling). A Zeeman slower consists of a cylinder, through which an atomic beam travels, a pump laser that counterpropagates with respect to the beam's direction , and a magnetic field (commonly produced by a solenoid-like coil) t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
