Chapter 1 Production of entangled photons Roll Number : MP12014 Name : S.Srikanth 1.1 Introduction Quantum entanglement occurs when a group of particles interact in a way, such that their quantum state cannot be described independently. As a consequence, all measurables such as position, momentum, polarization etc, are correlated. This is remarkable and sometimes seems paradoxical. The debate on this phenomena dates back to the days of Einstein, recalling the seminal work "The EPR paradox" [1]. This phenomena can be attributed solely to the nature of quantum measurement which deviates radically from classical measurements. Many experiments since have con rmed the validity of such a phenomena. We will not delve deep into these debates. Photon Entanglement Consider a system of two photons, label them signal and idler (historical reasons!). The photons can be distinguished as they are heading in dif- ferent directions. We assume that the photons have the polarization state described by the following wave function [2]: j Belli = 1 p2 (jV isjV ii + jHisjHii) (1.1) 12 CHAPTER 1. PRODUCTION OF ENTANGLED PHOTONS where jV i and jHi refer to horizontal or vertical polarizations and subscripts indicate signal or idler. The notation in the above equation means that the states are entangled and hence, cannot be factored into simple product of signal and idler states. If the polarizations of the photons are measured in the H,V basis there are two possible outcomes: both vertical or both horizontal. Now one can choose to measure in the rotated basis jV i = cos jV i sin jHi (1.2) jH i = sin jV i + cos jHi (1.3) The polarizers are rotated at an angle and measurements are made. It can be seen plainly that, on measurement both the photons are in... ... middle of paper ... ...2 sin2lcos )+C (1.11) where A is number of entangled pairs and C is an o set.O set is necessary as some coincidences are observed even when = 00; = 900. Hence, we now have a way to count the number of entangled pairs. We need to calibrate the above equation and a rough idea of purity of the entangled states can be found by nding N(00; 00):N(900,900) etc. 1.5 Summary and Discussion Non-locality is a major theme pondered over in fundamental physics. As pointed out by Einstein quantum mechanics seems to give rise to "spooky actions at distance". A method to produce entangled photons using a laser source and a non-linear crystal has been explained. The6 CHAPTER 1. PRODUCTION OF ENTANGLED PHOTONSBibliography [1] Arvind and Arvind, Quantum tomography Physical Review A73, 211- 215 (2014). [2] Neilson and Chuang, Quantum Computation and Quantum Informa- tion ........ 7
(t)| (12) The −→ A , −→ C vectors are calculated as in equations 13 and 14 −→ A = 2 −→ A . −→ r 1 − −→ a (13)
Throughout the past century, investigations of quantum and particle physics phenomena have proven to show the most significant concepts and ideas in the physical and sub-atomic world. However, the discoveries yet to be made are endless. One of the most fascinating concepts in the sub-atomic universe is the idea of spintronics. Spintronics is the quantum study of the independent angular momentum (not to be confused with the orbital angular momentum of the electron) of a particle, typically that of an electron (Introduction). An electron is a fundamental particle, with a negative charge, and is independently studied in the process of spintronic devices. The spin angular momentum of electrons is ±½ћ. Devices that use the properties
The novel, Alice and Quantum Land, by Robert Gilmore is an adventure in the Quantum universe. Alice, a normal teenage girl, goes through quantum land and understands what quantum is and how it works. The quantum world is a difficult one to understand, as its nature is one of complex states of being, natures, principles, notions, and the like. When these principles or concepts are compared with the macro world, one can find great similarities and even greater dissimilarities between the world wherein electrons rule, and the world wherein human beings live. In Alice in Quantumland, author Robert Gilmore converts the original tale of Alice in Wonderland from a world of anthropomorphic creatures into the minute world of quantum mechanics, and attempts to ease the reader into this confusing world through a series of analogies (which comprise an allegory) about the principles of quantum mechanics. Through Alice’s adventure she comes across some ideas or features that contradict real world ideas. These ideas are the following: Electrons have no distinguishing spin, the Pauli Exclusion Principle, Superposition, Heisenberg Uncertainty Principle, and Interference and Wave Particle Duality.
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Hypnosis and Weight Loss Hypnosis has many practical uses, and these days it is becoming increasingly popular as a method of behavior modification. The Internet contains many advertisements for self-help programs that use hypnosis to reduce stress, quit smoking, or lose weight. In the area of hypnosis and weight loss, there are many web sites for both products and services for sale that promise to help anyone lose weight. Hypnosis uses suggestions to change a person's behavior and eating habits in order to facilitate weight loss. What are the expected outcomes?
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Of the many counter intuitive quirks of quantum mechanics, the strangest quirk is perhaps the notion of quantum entanglement. Very roughly, quantum entanglement a phenomenon where the state of a large system cannot be described by the state of the smaller systems that compose it. On the standard metaphysical interpretation of quantum entanglement, this is taken to show that there exists emergent properties1. If this standard interpretation is correct, it seems that physics paints a far different picture of the world then commonsense leads one to believe.
Particle Physics plays an important role in attempting to answer many modern cosmological theories, notably: dark matter, structure formation, baryogenesis and nucleosynthesis. I am going to discuss some of connections between particle physics and cosmology and investigate how experimental particle physics and cosmology can complement each other and how dependable the connections are.
The way that each individual interprets, retrieves, and responds to the information in the world that surrounds you is known as perception. It is a personal way of creating opinions about others and ourselves in everyday life and being able to recognize it under various conditions. Each person’s perceptions are used as a kind of filter that every piece of information has to pass through before it determines the effect that it has or will have on the person from the stimulus. It is convincing to believe that we create multiple perceptions about different situations and objects each day. Perceptions reflect our opinions in many ways. The quality of a person’s perceptions is very important and can affect the response that is given through different situations. Perception is often deceived as reality. “Through perception, people process information inputs into responses involving feelings and action.” (Schermerhorn, et al.; p. 3). Perception can be influenced by a person’s personality, values, or experiences which, in turn, can play little role in reality. People make sense of the world that they perceive because the visual system makes practical explanations of the information that the eyes pick up.
According to Shannon’s rules, if the data we are going to encrypt is much lesser than the key in length and the same key we ...
“Just as a candle cannot burn without fire, men cannot live without a spiritual life.” According to Buddha, everyone needs some form of spirituality to define his or her life and existence. Webster Dictionary defines spiritualism as “a system of beliefs or religious practices based on supposed communication with the spirits of the dead, often times through mediums.” Though this is one general definition of spiritualism, this concept is one that does not hold a conclusive meaning. Each and every single person has the ability and right to create and practice their own idea of spiritualism. From ancient times to present day, the term and practice of spirituality has transformed, particularly from region to region. Despite the discrepancies in practices and overall understanding of this idea, spirituality has had an effect and impact upon all of humanity since the creation of time. This religion that is believed to have been established in the early eighteen hundreds, after two little girls claimed to have the ability to talk to spirits, sparked interest in this spiritual movement, allowing it to spread rather rapidly over many geographical locations. Aside from being recognized as a religion, spiritualism is also believed to be a form of philosophy and a science in which spiritualists believe that there is life after death and try to demonstrate this through the ability of attempting to communicate with those that have passed on. Spiritualism was socially different from other religions in existence at the time because it presented followers with a more tolerant belief system that assimilated the principles and facts from a selection the world's religions. Spiritualism also made it acceptable for women to play a disti...
The year 2012 was not only memorable to physicists for its breakthroughs, which include the galaxy motion cluster, neutrino-based communication or the method to see through opaque materials. But it is memorable because 2012 was the year that the physicists working in the Large Hadron Collider announced the detection of the Higgs boson particle.
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