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Gray Molasses
Gray molasses is a method of Sub-Doppler cooling, sub-Doppler laser cooling of atoms. It employs principles from Sisyphus cooling in conjunction with a so-called "dark" state whose transition to the excited state is not addressed by the resonant lasers. Ultracold atomic physics experiments on atomic species with poorly-resolved hyperfine structure, like isotopes of lithium and potassium, often utilize gray molasses instead of Sisyphus cooling as a secondary cooling stage after the ubiquitous Magneto-optical trap, magneto-optical trap (MOT) to achieve temperatures below the Doppler cooling#Minimum temperature, Doppler limit. Unlike a MOT, which combines a molasses force with a confining force, a gray molasses can only slow but not trap atoms; hence, its efficacy as a cooling mechanism lasts only milliseconds before further cooling and trapping stages must be employed. Overview Like Sisyphus cooling, the cooling mechanism of gray molasses relies on a two-photon Raman spectroscopy, R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sub-Doppler Cooling
Sub-Doppler cooling is a class of laser cooling techniques that reduce the temperature of atoms and molecules below the Doppler cooling limit. In experiment implementation, Doppler cooling is limited by the broad natural linewidth of the lasers used in cooling. Regardless of the transition used, however, Doppler cooling processes have an intrinsic cooling limit that is characterized by the momentum recoil from the emission of a photon from the particle. This is called the recoil temperature and is usually far below the linewidth-based limit mentioned above. By laser cooling methods beyond the two-level approximations of atoms, temperature below this limit can be achieved. Optical pumping between the sublevels that make up an atomic state introduces a new mechanism for achieving ultra-low temperatures. The essential feature of sub-Doppler cooling is the non-adiabaticity of the moving atoms to the light field. For a spatially dependent light field, the orientation of moving atoms is ... [...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 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 physicist and former government official. He is a Nobel laureate and was the 12th [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atoms
Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium, and any atom that contains 29 protons is copper. Atoms with the same number of protons but a different number of neutrons are called isotopes of the same element. Atoms are extremely small, typically around 100 picometers across. A human hair is about a million carbon atoms wide. Atoms are smaller than the shortest wavelength of visible light, which means humans cannot see atoms with conventional microscopes. They are so small that accurately predicting their behavior using classical physics is not possible due to quantum effects. More than 99.94% of an atom's mass is in the nucleus. Protons have a positive electric charge a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Cooling
Laser cooling includes several 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. It is a routinely used in atomic physics experiments where the laser-cooled atoms are manipulated and measured, or in technologies, such as atom-based quantum computing architectures. Laser cooling reduces the random motion of particles or the random vibrations of mechanical systems. For atoms and molecules this reduces Doppler shifts in spectroscopy, allowing for high precision measurements and instruments such as optical clocks. The reduction in thermal energy also allows for efficient loading of atoms and molecules into traps where they can be used in experiments or atom-based devices for longer periods of time. Laser cooling relies on the momen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Detuning
In optical physics, laser detuning is the tuning of a laser to a frequency that is slightly off from a quantum system's resonant frequency. When used as a noun, the laser detuning is the difference between the resonance frequency of the system and the laser's optical frequency (or wavelength). Lasers tuned to a frequency below the resonant frequency are called ''red-detuned'', and lasers tuned above resonance are called ''blue-detuned''. This technique is essential in many AMO physics experiments and associated technologies, as it allows the manipulation of light-matter interactions with high precision. Detuning has use cases in research fields including quantum optics, laser cooling, and spectroscopy. It is also fundamental to many modern and emerging atomic and quantum technologies, such as atomic clocks, quantum computers, and quantum sensors. By adjusting the detuning, researchers and engineers can control absorption, emission, and scattering processes, making it a versatile ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gray Molasses Cooling Cycle
Grey (more frequent in British English) or gray (more frequent in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning that it has no chroma. It is the color of a cloud-covered sky, of ash, and of lead. The first recorded use of ''grey'' as a color name in the English language was in 700 CE.Maerz and Paul ''A Dictionary of Color'' New York:1930 McGraw-Hill Page 196 ''Grey'' is the dominant spelling in European and Commonwealth English, while ''gray'' is more common in American English; however, both spellings are valid in both varieties of English. In Europe and North America, surveys show that gray is the color most commonly associated with neutrality, conformity, boredom, uncertainty, old age, indifference, and modesty. Only one percent of respondents chose it as their favorite color. Etymology ''Grey'' comes from the Middle English or , from the Old English , and is related to the Dutch and German ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonadiabatic Coupling
Vibronic coupling (also called nonadiabatic coupling or derivative coupling) in a molecule involves the interaction between electronic and nuclear vibrational motion. The term "vibronic" originates from the combination of the terms "vibrational" and "electronic", denoting the idea that in a molecule, vibrational and electronic interactions are interrelated and influence each other. The magnitude of vibronic coupling reflects the degree of such interrelation. In theoretical chemistry, the vibronic coupling is neglected within the Born–Oppenheimer approximation. Vibronic couplings are crucial to the understanding of nonadiabatic processes, especially near points of conical intersections. The direct calculation of vibronic couplings used to be uncommon due to difficulties associated with its evaluation, but has recently gained popularity due to increased interest in the quantitative prediction of internal conversion rates, as well as the development of cheap but rigorous ways ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rabi Frequency
The Rabi frequency is the frequency at which the Probability amplitude, probability amplitudes of two atomic electron transition, atomic energy levels fluctuate in an oscillating electromagnetic field. It is proportional to the transition dipole moment of the two levels and to the amplitude (''not'' Irradiance, intensity) of the electromagnetic field. Population transfer between the levels of such a 2-level system illuminated with light exactly resonant with the difference in energy between the two levels will occur at the Rabi frequency; when the incident light is detuned from this energy difference (detuned from resonance) then the population transfer occurs at the #Generalized Rabi frequency, generalized Rabi frequency. The Rabi frequency is a semiclassical concept since it treats the atom as an object with quantized Energy level, energy levels and the electromagnetic field as a continuous wave. In the context of a nuclear magnetic resonance experiment, the Rabi frequency is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Product State
In quantum mechanics, separable states are multipartite quantum states that can be written as a convex combination of product states. Product states are multipartite quantum states that can be written as a tensor product of states in each space. The physical intuition behind these definitions is that product states have no correlation between the different degrees of freedom, while separable states might have correlations, but all such correlations can be explained as due to a classical random variable, as opposed to being due to entanglement. In the special case of pure states the definition simplifies: a pure state is separable if and only if it is a product state. A state is said to be entangled if it is not separable. In general, determining if a state is separable is not straightforward and the problem is classed as NP-hard. Separability of bipartite systems Consider first composite states with two degrees of freedom, referred to as ''bipartite states''. By a postulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gray Molasses Raman Transition
Grey (more frequent in British English) or gray (more frequent in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning that it has no chroma. It is the color of a cloud-covered sky, of ash, and of lead. The first recorded use of ''grey'' as a color name in the English language was in 700 CE.Maerz and Paul ''A Dictionary of Color'' New York:1930 McGraw-Hill Page 196 ''Grey'' is the dominant spelling in European and Commonwealth English, while ''gray'' is more common in American English; however, both spellings are valid in both varieties of English. In Europe and North America, surveys show that gray is the color most commonly associated with neutrality, conformity, boredom, uncertainty, old age, indifference, and modesty. Only one percent of respondents chose it as their favorite color. Etymology ''Grey'' comes from the Middle English or , from the Old English , and is related to the Dutch and German ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linewidth
A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules. These "fingerprints" can be compared to the previously collected ones of atoms and molecules, and are thus used to identify the atomic and molecular components of stars and planets, which would otherwise be impossible. Types of line spectra Spectral lines are the result of interaction between a quantum system (usually atoms, but sometimes molecules or atomic nuclei) and a single photon. When a photon has about the right amount of energy (which is connected to its frequency) to allow a change in the energy state of the system (in the case of an atom this is usually an electron changing orbitals), the photon is absorbed. Then the energy will be spontaneously re-emitted, either as one photon at the same ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AC Stark Effect
AC, A.C., A/C, or Ac often refers to: * Air conditioning, often abbreviated as A/C * Alternating current, a type of electrical current in which the current repeatedly changes direction AC, A.C. or Ac may also refer to: Arts and entertainment Gaming * ''Ace Combat'', a series of combat flight simulator games * ''Animal Crossing'', a series of community simulation games * ''Anonymous;Code'', a visual novel in the Science Adventure series * '' Another Code'', a series of adventure games * ''Armored Core'', a series of mecha-based third person shooter games * ''Asheron's Call'', a fantasy massively multiplayer online role-playing game * ''Assassin's Creed'', a series of action-adventure games * ''Assetto Corsa'', a racing simulator game * ''Astral Chain'', an action-adventure hack and slash game * Armor Class, a combat-related parameter in the ''Dungeons & Dragons'' role playing game system * A.C., a character in '' Fortnite: Save the World'' Music * A.C. Newman, solo stage name f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
