{"id":270,"date":"2019-12-05T03:12:56","date_gmt":"2019-12-05T03:12:56","guid":{"rendered":"https:\/\/hadron893716717.wordpress.com\/?p=270"},"modified":"2020-09-06T19:59:29","modified_gmt":"2020-09-06T19:59:29","slug":"the-quantum-zeno-effect-explained","status":"publish","type":"post","link":"https:\/\/sites.imsa.edu\/hadron\/2019\/12\/05\/the-quantum-zeno-effect-explained\/","title":{"rendered":"The ‘Quantum Zeno Effect’ Explained"},"content":{"rendered":"\r\n

Written by alexander zhang<\/h2>\r\n\r\n\r\n\r\n

Greek philosopher Zeno of Elea once had an interesting thought (as philosophers do): if an arrow in flight is examined at an instant in time, the arrow appears to be motionless. However, if the arrow is motionless at every instant in time, and time is entirely composed of instants, then the idea of \u201cmotion\u201d is complete bogus. This posed an interesting mathematical problem.<\/p>\r\n\r\n\r\n\r\n

Thankfully, \u201cmotion\u201d was later un-bogused with the power of calculus. An intuitive refutation of Zeno\u2019s paradox was provided by Aristotle, who noted that “time is not composed of indivisible nows any more than any other magnitude is composed of indivisibles.\u201d That is, instantaneous moments in time do not exist because it is impossible to complete a task (such as firing an arrow from one point to another) with infinite steps. Bertrand Russell further criticized Zeno\u2019s model of motion, arguing that, while it is true that an arrow cannot be \u201cin motion\u201d at an infinitely small duration of time, all motion requires is for the arrow to be at a point at one time, another point at another time, and at the appropriate points during the intervening time.\u00a0<\/p>\r\n\r\n\r\n\r\n

Zeno\u2019s paradox may not be successful in dismantling the foundations of motion, but Zeno may have been pleased to know that his ideas helped to name an effect observed in the quantum realm. To preface this, it\u2019s important to acknowledge that slapping the word \u201cquantum\u201d in front of a disproved paradox doesn\u2019t necessarily make it any more sensible, but the quantum Zeno effect\u2014a feature of quantum systems with an idea similar to Zeno\u2019s arrow paradox\u2014is a very real and observable phenomenon.\u00a0\u00a0<\/p>\r\n\r\n\r\n\r\n

To put the quantum Zeno effect into understandable (yet nowhere near accurate) terms, take a common example: waiting for something to load. Suppose Zeno wanted to watch a YouTube video, but it was taking a long time to load and he was growing impatient. Then an idea struck him: if he closed his eyes while waiting for the video to load, periodically opening them to check on the progress, he might make it seem to speed up! He does this, measuring the state of the video frequently. However, he finds that his video\u2014which usually finishes loading after a short while\u2014doesn\u2019t load at all. In fact, everytime he glances at the loading icon, it seems like nothing changed! That\u2019s because, according to the quantum Zeno effect, nothing\u2014or at least very little\u2014did change. By measuring the system frequently enough at specific intervals, Zeno was able to arrest his video\u2019s time evolution (that\u2019s assuming that his video is actually a particle abiding to quantum laws), keeping the video at its initial conditions. Put into simple terms, the quantum Zeno effect describes how a quantum system can be \u201cfrozen\u201d by measuring it frequently enough.\u00a0<\/p>\r\n\r\n\r\n\r\n

A better metaphor to explain this phenomenon is Schrodinger\u2019s cat. Schrodinger\u2019s famous thought experiment hypothesized that a cat locked in a box with a 50% of dying (usually due to a radioactive atom) will be half-dead and half-alive, a victim of the duality of conditions that exist within quantum physics. What\u2019s curious is that the quantum Zeno effect can actually ensure that the cat always lives. Assume the fate of the cat relies on a radioactive atom which has a 50% chance of decaying and triggering the destruction of a poison vial. Plotting the probability that the survivability of the cat over an x-value of time, a negatively sloped graph arises. This\u2014while tragic\u2014is to be expected; a greater value of time leads to a higher probability that the atom has decayed and, thus, a lower survivability of the cat. However, if the atom is \u201cobserved\u201d over the course of its decay, a more lively graph takes form:\u00a0<\/p>\r\n\r\n\r\n\r\n

\"\"<\/figure>\r\n\r\n\r\n\r\n

The \u201cbounces\u201d in the graph correspond with the times at which the system is measured, while the dashed line depicts the survivability of the cat without measurements.\u00a0<\/p>\r\n\r\n\r\n\r\n

\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Everytime the system is measured, and the atom still hasn\u2019t decayed (in other words, it\u2019s still in its initial conditions), it\u2019s as if nothing happened at all. As a result, the system \u201cresets\u201d in a sense, and the process begins again. So, Schrodinger\u2019s cat lives on, and Zeno\u2019s quantum YouTube video loads in an endless spiral. As strange as this may seem, the quantum Zeno effect has been experimentally proven in the real world. Researchers from Cornell found ways to use the quantum Zeno effect to freeze the tunneling of atoms\u2014a phenomenon that usually occurs when atoms are exposed to extremely cold temperatures. Instead of \u201ctunneling\u201d place to place as a result of having nearly 0 velocity, the atoms exhibited reduced tunneling when measured.\u00a0<\/p>\r\n\r\n\r\n\r\n

Thankfully, the quantum Zeno effect isn\u2019t only understood under the context of \u201cmagic.\u201d The active action of measuring\u2014that is, in the Cornell researcher\u2019s case, shining an imaging laser on atoms\u2014served as an outside force, disrupting the sensitive balance of quantum systems. This caused for the reduction of tunneling. As measurements by the imaging laser became brighter and\/or more frequent, the tunneling was dramatically reduced.<\/p>\r\n\r\n\r\n\r\n

It\u2019s evident that the quantum Zeno effect isn\u2019t yet readily applicable for everyday life. It may be a long time until this phenomenon, like many other quantum phenomena, is fully understood and ready to be taught in high school classrooms. Even so, it\u2019s valuable to take a look at what really is reality and explore the stranger parts of it. After all, that\u2019s what Zeno of Elea did when he took an aspect of reality\u2014motion\u2014and thought about it for a little while, even if his work is unfounded today. Quantum physics is still a relatively new and unexplored realm of physics, and it\u2019s up to the thinkers of today to un-bogus it.\u00a0<\/p>\r\n\r\n\r\n\r\n

Felix Pollock – The quantum Zeno effect: how curiosity can save Schrodinger’s cat. (2015, May 28). Retrieved from https:\/\/youtu.be\/3WHPiH0pNeo<\/a>.<\/p>\r\n\r\n\r\n\r\n

\u0158eh\u00e1\u010dek, J., Hradil, Z., Pe\u0159ina, J., Pascazio, S., Facchi, P., & Zawisky, M. (2008, May 30). Advanced Neutron Imaging and Sensing. Retrieved from https:\/\/www.sciencedirect.com\/science\/article\/pii\/S1076567005420029<\/a>.<\/p>\r\n\r\n\r\n\r\n

Steele, B. (2015, October 22). ‘Zeno effect’ verified: Atoms won’t move while you watch. Retrieved from http:\/\/news.cornell.edu\/stories\/2015\/10\/zeno-effect-verified-atoms-wont-move-while-you-watch.<\/p>\r\n","protected":false},"excerpt":{"rendered":"

Written by alexander zhang Greek philosopher Zeno of Elea once had an interesting thought (as philosophers do): if an arrow in flight is examined at an instant in time, the arrow appears to be motionless. However, if the arrow is motionless at every instant in<\/p>\n","protected":false},"author":568,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"footnotes":""},"categories":[12],"tags":[],"class_list":["post-270","post","type-post","status-publish","format-standard","hentry","category-physics"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/posts\/270","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/users\/568"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/comments?post=270"}],"version-history":[{"count":1,"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/posts\/270\/revisions"}],"predecessor-version":[{"id":694,"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/posts\/270\/revisions\/694"}],"wp:attachment":[{"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/media?parent=270"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/categories?post=270"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sites.imsa.edu\/hadron\/wp-json\/wp\/v2\/tags?post=270"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}