Quantum optics is a field of research in physics, dealing with the application of quantum mechanics to phenomena involving light and its interactions with matter. A black hole concept drawing by NASA. Physics (from the Greek, φυσικός (physikos), natural, and φύσις (physis), nature) is the science of the natural world dealing with the fundamental constituents of the universe, the forces they exert on one another, and the results produced by these forces. ... Fig. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific context, electromagnetic radiation of any wavelength. ... Matter is commonly referred to as the substance of which physical objects are composed. ...

History of quantum optics

Light is made up of particles called photons and hence inherently is "grainy" (quantized); quantum optics is the study of the nature and effects of this. The first indication that light might be quantized came from Max Planck in 1899 when he correctly modelled blackbody radiation by assuming that the exchange of energy between light and matter only occurred in discrete amounts he called quanta. It was unknown whether the source of this discreteness was the matter or the light. In 1905, Albert Einstein published the theory of the photoelectric effect. It appeared that the only possible explanation for the effect was the existence of particles of light called photons. Later, Bohr showed that the atoms were also quantized, in the sense that they could only emit discrete amounts of energy. The understanding of the interaction between light and matter following from these developments not only formed the basis of quantum optics but also were crucial for the development of quantum mechanics as a whole. However, the subfields of quantum mechanics dealing with matter-light interaction were principally regarded as research into matter rather than into light and hence, one rather spoke of atom physics and quantum electronics. In physics, the photon (from Greek φοτος, meaning light) is a quantum of excitation of the quantised electromagnetic field and is one of the elementary particles studied by quantum electrodynamics (QED) which is the oldest part of the Standard Model of particle physics. ... Max Planck This article is about Planck, the German physicist. ... 1899 was a common year starting on Sunday (see link for calendar). ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... 1905 (MCMV) was a common year starting on Sunday (see link for calendar). ... Albert Einstein photographed by Oren J. Turner in 1947. ... The photoelectric effect is the emission of electrons from matter upon the absorption of electromagnetic radiation, such as ultraviolet radiation or x-rays. ... Niels Bohr Niels Henrik David Bohr (October 7, 1885 – November 18, Danish physicist who made essential contributions to understanding atomic structure and quantum mechanics. ... Matter is commonly referred to as the substance of which physical objects are composed. ... Atomic physics (or atom physics) is physics of the electron hull of atoms. ... Quantum electronics is an area of physics dealing with the effect of quantum mechanics on the behaviour of electrons in solid-state matter. ...

This changed with the invention of the laser in 1950. Laser science—i.e., research into principles, design and application of these devices—became an important field, and the quantum mechanics underlying the laser's principles was studied now with more emphasis on the properties of light, and the name quantum optics became customary. The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ... 1950 (MCML) was a common year starting on Sunday (link will take you to calendar). ... Laser science is a branch of optics that describes the theory and practice of lasers. ...

As laser science needed good theoretical foundations, and also because research into these soon proved very fruitful, interest in quantum optics rose. Following the work of Dirac in quantum field theory, Roy J. Glauber and Leonard Mandel applied quantum theory to the electromagnetic field in the 1950s and 1960s to gain a more detailed understanding of photodetection and the statistics of light (see degree of coherence). This led to the introduction of the coherent state as a quantum description of laser light and the realization that some states of light could not be described with classical waves. In the 1970s, Kimball demonstrated the first source of light which required a quantum description: a single atom that emitted one photon at a time. This was the first conclusive evidence that light was made up of photons. Another quantum state of light with certain advantages over any classical state, squeezed light, was soon proposed. At the same time, development of short and ultrashort laser pulses—created by Q switching and modelocking techniques—opened the way to the study of unimaginably fast ("ultrafast") processes. Applications for solid state research (e.g. Raman spectroscopy) were found, and mechanical forces of light on matter were studied. The latter led to levitating and positioning clouds of atoms or even small biological samples in an optical trap or optical tweezers by laser beam. This, along with Doppler cooling was the crucial technology needed to achieve the celebrated Bose-Einstein condensation. Paul Adrien Maurice Dirac Paul Adrien Maurice Dirac, OM (IPA: [dɪræk]) (August 8, 1902 – October 20, 1984) was a British theoretical physicist and a founder of the field of quantum physics. ... Quantum field theory (QFT) is the application of quantum mechanics to fields. ... Roy Jay Glauber (born 1 September 1925) is the Mallinckrodt Professor of Physics at Harvard University and Adjunct Professor of Optical Sciences at the University of Arizona. ... Leonard Mandel Mandel was the Lee DuBridge Professor Emeritus of Physics and Optics at the University of Rochester, having become emeritus only a few months before he died, at the age of 73, at his home in Pittsford, New York. ... // Events and trends This map shows two essential global spheres during the Cold War in 1959. ... The 1960s decade refers to the years from 1960 to 1969, inclusive. ... Statistical mechanics is the application of statistics, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force. ... In optics, correlation functions are used to quantify the statistical and coherence properties of an electromagnetic field. ... In quantum mechanics a coherent state is a specific kind of quantum state of the quantum harmonic oscillator whose dynamics most closely resemble the oscillating behaviour of a classical harmonic oscillator system. ... The 1970s decade refers to the years from 1970 to 1979, inclusive. ... Introduction In optics, an ultrashort pulse of light is an electromagnetic pulse whose time duration is on the order of the femtosecond ( second). ... Q-switching, sometimes known as giant pulse formation, is a technique by which a laser can be made to produce a pulsed output beam. ... Modelocking is a technique in optics by which a laser can be made to produce pulses of light of extremely short duration, on the order of picoseconds (10-12s) or femtoseconds (10-15s). ... In physics, ultrafast describes events that occur on femtosecond timescales. ... Raman spectroscopy is a spectroscopic technique used in condensed matter physics and chemistry to study vibrational, rotational, and other low-frequency modes in a system. ... Optical tweezers are the application of a laser beam to physically move very small translucent objects. ... Optical tweezers make use of a laser beam to provide a mechanical force (in the range of pico to femto Newtons) to physically move microscopic objects around with nanometer precision. ... A Bose-Einstein condensate is a gaseous superfluid phase formed by atoms cooled to temperatures very near to absolute zero. ...

Other remarkable results are the demonstration of quantum entanglement, quantum teleportation, and (recently, in 1995) quantum logic gates. The latter are of much interest in quantum information theory, a subject which partly emerged from quantum optics, partly from theoretical computer science. Quantum entanglement is a quantum mechanical phenomenon in which the quantum states of two or more objects have to be described with reference to each other, even though the individual objects may be spatially separated. ... This article might not be written in the formal tone expected of an encyclopedia entry. ... 1995 (MCMXCV) was a common year starting on Sunday of the Gregorian calendar. ... A quantum gate or quantum logic gate is a rudimentary quantum circuit operating on a small number of qubits. ... Quantum information science is a field of research at the interface of quantum mechanics and computer science. ... Wikibooks Wikiversity has more about this subject: School of Computer Science Open Directory Project: Computer Science Downloadable Science and Computer Science books Collection of Computer Science Bibliographies Belief that title science in computer science is inappropriate Categories: | ...

Today's fields of interest among quantum optics researchers include parametric down-conversion, parametric oscillation, even shorter (attosecond) light pulses, use of quantum optics for quantum information, manipulation of single atoms, Bose-Einstein condensates, their application, and how to manipulate them (a sub-field often called atom optics), and much more. Parametric down-conversion is an important process in quantum optics. ... An optical parametric oscillator (OPO) converts a input laser wave (called pump) into two output waves of lower frequency () by means of nonlinear optical interaction. ... To help compare orders of magnitude of different times this page lists times between 10-16 seconds and 10-15 seconds (100 attoseconds and 1 femtosecond) See also times of other orders of magnitude. ... In quantum mechanics, quantum information is physical information that is held in the state of a quantum system. ... A Bose-Einstein condensate is a phase of matter formed by bosons cooled to temperatures very near to absolute zero. ...

Research into quantum optics, which aims to bring photons into use for information transfer and computation, is now often called photonics to emphasize the claim that photons and photonics will take the role that electrons and electronics now have. This article is in need of attention from an expert on the subject. ... Properties The electron is a fundamental subatomic particle which carries a negative electric charge. ... Two digital voltmeters The field of electronics is the study and use of systems that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. ...

Concepts of quantum optics

According to quantum mechanics, light may be considered not only as an electro-magnetic wave but also as a "stream" of particles called photons which travel with c, the vacuum speed of light. These particles should not be considered to be classical billiard balls, but as quantum mechanical particles described by a wavefunction spread over a finite region. Each particle carries one quantum of energy equal to hf, where h is Planck's constant and f is the frequency of the light. The postulation of the quantization of light by Max Planck in 1899 and the discovery of the general validity of this idea in Albert Einstein's 1905 explanation of the photoelectric effect soon led physicists to realize the possibility of population inversion and the possibility of the laser. Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ... In physics, the photon (from Greek φοτος, meaning light) is a quantum of excitation of the quantised electromagnetic field and is one of the elementary particles studied by quantum electrodynamics (QED) which is the oldest part of the Standard Model of particle physics. ... Cherenkov effect in a swimming pool nuclear reactor. ... In quantum mechanics, the wavefunction associated with a particle such as an electron, is a complex-valued function ψ defined over a portion of space and normalized in such a way that In Max Borns probabilistic interpretation of the wavefunction, the amplitude squared of the wavefunction |ψ(x)|2 is the... Generally, quantization is the state of being constrained to a set of discrete values, rather than varying continuously. ... Max Planck This article is about Planck, the German physicist. ... 1899 was a common year starting on Sunday (see link for calendar). ... Albert Einstein photographed by Oren J. Turner in 1947. ... 1905 (MCMV) was a common year starting on Sunday (see link for calendar). ... The photoelectric effect is the emission of electrons from matter upon the absorption of electromagnetic radiation, such as ultraviolet radiation or x-rays. ... In physics, specifically statistical mechanics, the concept of population inversion is of fundamental importance in laser science because the production of a population inversion is a necessary step in the workings of a laser. ... The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ...

This kind of use of statistical mechanics is the fundament of most concepts of quantum optics: Light is described in terms of field operators for creation and annihilation of photons—i.e. in the language of quantum electrodynamics. Statistical mechanics is the application of statistics, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force. ... Quantum electrodynamics (QED) is a quantum field theory of electromagnetism. ...

A frequently encountered state of the light field is the coherent state as introduced by Roy J. Glauber in 1963. This state, which can be used to approximately describe the output of a single-frequency laser well above the laser threshold, exhibits Poissonean photon number statistics. Via certain nonlinear interactions, a coherent state can be transformed into a squeezed coherent state, which can exhibit super- or sub-Poissonean photon statistics. Such light is called squeezed light. Other important quantum aspects are related to correlations of photon statistics between different beams. For example, parametric nonlinear processes can generate so-called twin beams, where ideally each photon of one beam is associated with a photon in the other beam. In quantum mechanics a coherent state is a specific kind of quantum state of the quantum harmonic oscillator whose dynamics most closely resemble the oscillating behaviour of a classical harmonic oscillator system. ... Roy Jay Glauber (born 1 September 1925) is the Mallinckrodt Professor of Physics at Harvard University and Adjunct Professor of Optical Sciences at the University of Arizona. ... 1963 (MCMLXIII) was a common year starting on Tuesday (link will take you to calendar). ... The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ... In probability theory and statistics, the Poisson distribution is a discrete probability distribution. ... In physics, a squeezed coherent state is every state in the Hilbert space of quantum mechanics that saturates the uncertainty principle that is the product of the corresponding two operators takes on its minimum value: The simplest such state is the ground state of the quantum harmonic oscillator. ...

Atoms are considered as quantum mechanical oscillators with a discrete energy spectrum with the transitions between the energy eigenstates being driven by the absorption or emission of light according to Einstein's theory with the oscillator strength depending on the quantum numbers of the states. Oscillation is the periodic variation, typically in time, of some measure as seen, for example, in a swinging pendulum. ... The word discrete comes from the Latin word discretus which means separate. ... This article needs to be cleaned up to conform to a higher standard of quality. ... In linear algebra, the eigenvectors (from the German eigen meaning inherent, characteristic) of a linear operator are non-zero vectors which, when operated on by the operator, result in a scalar multiple of themselves. ... A quantum number is any one of a set of numbers used to specify the full quantum state of any system in quantum mechanics. ...

For solid state matter one uses the energy band models of solid state physics. This is important as understanding how light is detected (typically by a solid-state device that absorbs it) is crucial for understanding experiments. In solid-state physics, an energy band is a continuous range of values of energy that an electron may or may not have. ... Solid-state physics, the largest branch of condensed matter physics, is the study of rigid matter, or solids. ... Absorption has a number of meanings: In physics, absorption is a process in which particles of some sort encounter another material and are taken up by or even disappear in it. ...

External links

• An introduction to quantum optics of the light field
• Encyclopedia of laser physics and technology, with content on quantum optics (particularly quantum noise in lasers), by Rüdiger Paschotta
• Qwiki - A quantum physics wiki devoted to providing technical resources for practicing quantum physicists.