en>Monkbot: /* Other Applications */Task 5: Fix CS1 deprecated coauthor parameter errors

2014-05-14T06:20:30Z

Other Applications: Task 5: Fix CS1 deprecated coauthor parameter errors

← Older revision		Revision as of 08:20, 14 May 2014
Line 1:		Line 1:
	~~[[File:Cavity Optomechanics.png\|thumb\|The typical model for many structures in cavity optomechanics is an optical cavity consisting of a fixed mirror and a mechanical oscillator.]]~~		54 yr old Market Research Analyst Dwight from Meadow Lake, has several hobbies and interests which include matchstick modeling, Titan Empires Hack ([http://www.gameinformer.com/blogs/members/b/mercury1st_blog/archive/2014/10/21/titan-empires-hack-is-it-real.aspx More methods]) and crochet. Last year just made a trip National Archeological Park of Tierradentro.

	'''Cavity opto-mechanics''' is a branch of [[physics]] which focusses on the interaction between light and mechanical objects on low-energy scales. It is a cross field of [[optics]], [[quantum optics]], [[solid-state physics]] and [[materials science]]. The motivation for research on cavity optomechanics comes from ~~fundamental effects of [[Quantum mechanics\|quantum theory]] and [[gravity]]~~, ~~as well as technological applications.~~

	~~The name of the field relates to the main effect of interest, which is the enhancement of [[Radiation pressure\|radiation pressure interaction]] between light ([[photon]]s)~~ and matter using [[Optical cavity\|optical resonators (cavities)]]. One may envision optomechanical structures to allow the realization of [[Schrödinger's cat]]. Macroscopic objects consisting of billions of atoms share collective degrees of freedom which ~~may behave quantum mechanically~~, ~~e.g. a sphere of micrometer diameter being in a spatial~~ [[superposition]] between two different places. Such a quantum state of motion would allow to experimentally investigate [[decoherence]], which describes the process of objects transitioning between states which are described by quantum mechanics to states which are described by [[Newtonian mechanics]]. Optomechanical structures pave a new way for testing the predictions of quantum mechanics and decoherence models and thereby might allow to answer some of the most fundamental questions in modern physics.

	There is a broad range of experimental optomechanical systems which are almost equivalent in their description, but completely different in size, mass and frequency, ranging from attograms and gigahertz to kilograms and hertz. Cavity optomechanics was featured as the most recent ''milestone of photon history''<ref>http://www.~~nature~~.com/~~milestones~~/~~milephotons~~/~~full~~/~~milephotons23.html<~~/~~ref> in nature photonics along well established concepts and technology like [[Quantum information]], [[Bell inequalities]] and the [[laser]].~~

	~~== Concepts of cavity opto-mechanics ==~~
	~~According to the [[Light#Quantum_theory\|quantum theory of light]], every photon with wave number <math>k</math> carries a momentum <math>p = \hbar k<~~/~~math> with Planck's constant <math>\hbar</math> and the speed of light <math>c<~~/math>. This means that a photon which is reflected of a mirror surface transfers a momentum <math>\Delta p = 2 \hbar k</math> onto the mirror, since the net momentum has to be conserved. This effect is extremely small and can not be observed on most every-day objects, however it becomes bigger when the mass of the mirror is very small.

	Photons can be prepared in quantum (non-classical) states. If one assumes that quantum mechanics also describes the physics of the motion of a small mirror, it should be possible to use quantum states of photons to create quantum states of mirrors. Compared to most "typical" quantum objects like photons, electrons, atoms and small molecules, even a nanogram mirror which can just be seen under a microscope is larger by many orders of magnitude. This makes optomechanical structures the closest experimental neighbours to the quantum cat in Schrödinger's Gedankenexperiment.

	~~=== Enhancing the interaction between light and matter with optical cavities ===~~
	Since the momentum of photons is extremely small and not enough to change the position of a suspended mirror by more than its quantum mechanical position uncertainty, one needs to enhance the interaction. One possible way to do this is by using optical cavities. If a photon is enclosed between two mirrors, one being the oscillator and the other a heavy fixed one, it will bounce off the mirrors many times and transfer its momentum every time it hits the mirrors. The number of times a photon can transfer its momentum is directly related to the [[Fabry–Pérot interferometer\|finesse]] of the cavity, which can be improved with highly reflective mirror surfaces.

	Another advantage of optical cavities is that the modulation of the cavity length through an oscillating mirror can directly be seen in the spectrum of the cavity. The mechanics produce ''red'' and ''blue'' sidebands around the optical resonances, shifted by the mechanical frequency. These sidebands can then be used for [[Laser cooling\|optical cooling]] of the mechanical oscillator: By detuning incoming light from resonance to the red sideband, the photons can only enter the cavity if they take phonons with energy <math>\hbar \omega_m</math> from the mechanics. This effectively cools the device until a balance with heating mechanisms from the environment and laser noise is reached. Cavity cooling has successfully been used to cool devices to the quantum ground state. In the same fashion it is also possible to heat structures by detuning a laser to the blue side and thereby achieving strong accelerations in the mechanical oscillator.

	There are several different ways of applying cavities around optomechanical structures. In the ''reflective'' case the mechanical structure of interest is one end mirror of the cavity (or the whole cavity itself is a mechanical oscillator). In the ''dispersive'' case, a dispersive medium is brought into a cavity consisting of fixed massive mirrors. Both schemes are similar, though not entirely equivalent.<ref>Thompson, J. D., Zwickl, B. M., Jayich, A. M., Marquardt, F., Girvin, S. M., & Harris, J. G. E. (2008). Strong dispersive coupling of a high-finesse cavity to a micromechanical membrane. ''Nature'', 452(7183), 72-5. Nature Publishing Group. {{doi\|10~~.1038~~/~~nature06715}}<~~/ref> A third way of achieving coupling between mechanical structures and the light field within a cavity is through evanescent fields.<ref>Anetsberger, G., Arcizet, O., Unterreithmeier, Q. P., Rivière, R., Schliesser, A., Weig, E. M., Kotthaus, J. P., et al. (2009). Near-~~field cavity optomechanics with nanomechanical oscillators. Nature Physics, 5(12), 909~~-~~914. Nature Publishing Group. {{doi\|10.1038/nphys1425}}</ref>~~

	~~=== Mathematical treatment ===~~
	~~The full hamiltonian of the system can be motivated to be of the following form:<ref>Law, C. (1994). Effective Hamiltonian for the radiation in a cavity with a moving mirror and a time~~-~~varying dielectric medium. Physical Review A, 49(1), 433-437. {{doi\|10.1103/PhysRevA.49.433}}</ref>~~

	~~:<math>H=\hbar \omega_c a^\dagger a + \frac{1}{2} \hbar \omega_m (p_m^2+x_m^2) - \hbar g_0 a^\dagger a x_m + i \hbar E (a^\dagger e^{-i \omega_l t} - a e^{i \omega_l t})</math>~~

	with the cavity frequency <math>\omega_c</math>, the annihilation and creation operators of the cavity field <math>a</math> and <math>a^\dagger</math>, the momentum and position operators of the mechanics <math>p_m</math> and <math>x_m</math>, the coupling rate <math>g_0</math>, the laser input <math>E</math> and frquency <math>\omega_l</math>.

	~~== Relation to fundamental research ==~~
	~~One of the questions which are still subject to current debate~~ is the exact mechanism of decoherence. As Schrödinger pointed out, we would never see something like a cat in a quantum state. There needs to be something like a collapse of the quantum wave functions, which brings it from a quantum state to a pure classical state. Now one can ask where the boundary lies between objects with quantum properties and classical objects. Taking spatial superpositions as an example, there might be a size limit to objects which can be brought into superpositions, there might be a limit to the spatial separation of the centers of mass a super position or even a limit to the superposition of gravitational fields and its impact on small test masses. Those predictions could be checked with large mechanical structures which can be manipulated on a quantum level.<ref>Bose, S., Jacobs, K., & Knight, P. (1999). Scheme to probe the decoherence of a macroscopic object. Physical Review A, 59(5), 3204-3210. {{doi\|10.1103/PhysRevA.59.3204}}</ref>

	Some easier to check predictions of quantum mechanics is the prediction of negative [[Wigner quasi-probability distribution\|Wigner functions]] for certain quantum states,<ref>Simon Rips, Martin Kiffner, Ignacio Wilson-Rae, & Michael Hartmann. (2011). Cavity Optomechanics with Nonlinear Mechanical Resonators in the Quantum Regime - OSA Technical Digest (CD). CLEO/Europe and EQEC 2011 Conference Digest (p. JSI2_3). Optical Society of America. Retrieved from http://www.opticsinfobase.org/abstract.cfm?URI=EQEC-2011-JSI2_3</ref> measurement precision beyond the [[Quantum limit\|standard quantum limit]] using squeezed states of light<ref>Jaekel, M. T., & Reynaud, S. (1990). Quantum Limits in Interferometric Measurements. Europhysics Letters (EPL), 13(4), 301-306. {{doi\|10.1209/0295-5075/13/4/003}}</ref> or the asymmetry of the sidebands in the spectrum of a cavity near the quantum ground state.<ref>Safavi-Naeini, A. H., Chan, J., Hill, J. T., Alegre, T. P. M., Krause, A., & Painter, O. (2011). Measurement of the quantum zero-point motion of a nanomechanical resonator, 6. Retrieved from http://arxiv.org/abs/1108.4680</ref>

	~~== Applications ==~~
	~~Years before cavity opto-mechanics gained the status of an independent field of research, many of its techniques were already used in [[Gravitational wave detector]]s where~~ it is necessary to measure displacements of mirrors on the order of the Planck scale. Even if these detectors do not address the measurement of quantum effects, they encounter related issues ([[Shot noise#In optics\|photon shot noise]]) and use similar tricks ([[Squeezed coherent state\|squeezed states]]) to enhance the precision. Further applications include the development of quantum memory for [[quantum computer]]s<ref>Cole, G. D., & Aspelmeyer, M. (2011). Cavity optomechanics: Mechanical memory sees the light. Nature nanotechnology, 6(11), 690-~~1. Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. {{doi\|10.1038/nnano~~.~~2011.199}}</ref> and high precision [[Accelerometer\|acceleration sensors]~~]~~.<ref>Krause, A. G., Winger, M., Blasius, T. D., Lin, Q. & Painter, O. A high-resolution microchip optomechanical accelerometer. Nature Photonics (2012~~)~~. {{doi\|10.1038/nphoton.2012.245}}</ref>~~

	~~== Neighbouring fields ==~~
	~~Cavity opto-meachnics is closely related to [[Trapped ion quantum computer\|trapped ion]] physics~~ and ~~[[Bose-Einstein condensate]]s~~. ~~These systems share very similar Hamiltonians, but they have less particles (about 10 for ion traps and <math>10^5</math>-<math>10^8</math> for BECs) interacting with the field of light.~~

	~~== See also ==~~
	~~{{portal\|Physics}}~~
	*[[Radiation pressure]]
	*[[Quantum optics]]
	*[[Ground state]]
	*[[Quantum harmonic oscillator]]
	*[[Solid-state physics]]
	*[[Optical cavity]]
	*[[Schrödinger's cat]]
	*[[Decoherence]]

	~~== References ==~~
	~~<references />~~

	~~=== Further reading ===~~

	* Aspelmeyer, M., Gröblacher, S., Hammerer, K., & Kiesel, N. (2010). Quantum optomechanics—throwing a ~~glance [Invited]. Journal~~ of ~~the Optical Society of America B, 27(6), A189. OSA~~. ~~{{doi\|10.1364/JOSAB.27.00A189}}~~
	* Kippenberg, T. J., & Vahala, K. J. (2007). Cavity Opto-Mechanics. Optics Express, 15(25), 17172. OSA. {{doi\|10.1364/OE.15.017172}}
	* Romero-Isart, O., Pflanzer, A., Blaser, F., Kaltenbaek, R., Kiesel, N., Aspelmeyer, M., & Cirac, J. (2011). Large Quantum Superpositions and Interference of Massive Nanometer-Sized Objects. Physical Review Letters, 107(2). {{doi\|10.1103/PhysRevLett.107.020405}}

	~~[[Category:Optics]]~~

en>Anrnusna at 06:01, 17 September 2013

2013-09-17T06:01:28Z

Show changes

en>Trashbird1240: Disambiguated: fitness → fitness (biology)

2012-01-21T20:42:06Z

Disambiguated: fitness → fitness (biology)

New page

Does your company find itself lacking just a little in the service department? Are you getting complaints about perhaps not getting back once again to people or do you genuinely believe that you need to use a newer fresher design of marketing? That are available If that"s the case then perhaps it"s time that you started looking into one of the numerous autoresponder companies. These autoresponder companies can alter the face of your business and help you to pull in a lot more sales than you have ever noticed in the past. In fact, with a good autoresponder company on your own part you might up your organization as quickly as in one week. In regards to an autoresponder support you need choose the type you want. You may get an autoresponder service that would have been a software program or one that is a genuine autoresponder service. If you elect to obtain autoresponder service plans you"ll just make a onetime payment for them. Discover more on a partner article directory by clicking [http://www.indyarocks.com/blog/1742631/Email-Courses-And-Autoresponders lists of email addresses]. Normally, this is affordable and an easy task to do, as you want you"ll be as much times able to use your autoresponder support programs or programs and you will do not have to cover significantly more than your original investment. You may also elect to get an actual autoresponder service. That autoresponder service will save you time and energy in a huge way. It"s easy and so simple to use an autoresponder support that there"s a very good chance that you"ll never look right back. Many people have changed form an autoresponder company to a script and then regretted it. When you are utilizing a script and some thing goes wrong you have to determine where in actuality the problem lies and how to fix it. They do all of this hard work for you when you"re utilizing an autoresponder service. The problem is found by them and it is fixed by them at no cost. This is a great selling point on the part of an autoresponder company, particularly when you"re new to the whole idea. When you choose an autoresponder support you will also have the satisfaction realizing that they are keeping along with most of the newest and best developments in this market. Mass mailing is really a growing industry and it is changing all the time. You"ll have the advantages of getting most of the latest technology when you"ve signed to an autoresponder support. It"ll never change on its own if you are running your own program and you could possibly be missing out on some strong autoresponder service features. In the event you require to discover additional information on [http://www.purevolume.com/marketinglistspld/posts/7839568/Email+Courses+And+Autoresponders+ homeowner email lists], there are heaps of libraries you can investigate. Functions that could change your business for the better. An autoresponder support is really a easy and affordable method for you to retain in touch with potential customers. When you are using an autoresponder company you will always know you are making a splash, a large one and that you are getting the messages out to the general public. Therefore learn more about the many great autoresponder services on line today.. In case people require to get supplementary info on [http://www.revish.com/people/emaillistjez/ opt in email addresses], there are tons of databases you should investigate. In the event you loved this article and you want to receive much more information relating to [http://ovalranchtalk.wallinside.com health Insurance Individual] please visit our own web-page.

Genic capture - Revision history

en>Monkbot: /* Other Applications */Task 5: Fix CS1 deprecated coauthor parameter errors

en>Anrnusna at 06:01, 17 September 2013

en>Trashbird1240: Disambiguated: fitness → fitness (biology)