Algorithms<\/em> are recipes. A series of steps to follow. They accept inputs and deliver outputs. A good algorithm provides desired outputs quickly.\u00a0<\/p>\r\n\r\n\r\n\r\nHow do we analyze algorithms? That is, how “good” are they? We need a conceptual model for computing.\u00a0<\/p>\r\n\r\n\r\n\r\n
This is the area of computational complexity<\/em>, a branch of theoretical computer science, and as Dijkstra put it, has not much to do with a specific hardware or physical computer, but has to do with \u201cwhat a reasonable classical computer\u201d can be expected to do.<\/p>\r\n\r\n\r\n\r\nHow do you \u201cwrite\u201d these algorithms so that \u201chardware\u201d can execute its steps? This is the fourth thread: software<\/em>.<\/p>\r\n\r\n\r\n\r\nClassical computing uses software to translate algorithms, that were conceived using a conceptual computing model (of Turing), to instructions that the hardware (constructed using ideas from quantum mechanics) can execute.<\/p>\r\n\r\n\r\n\r\n
Quantum computing uses a different conceptual model.<\/p>\r\n\r\n\r\n\r\n
Information is not stored in bits<\/em>, that have a definite value<\/em> of zero or one at any given instant, but in qubits<\/em> \u2013 quantum bits \u2013 that store information as superposition<\/em> of zero and one, and so is both zero and<\/strong> one at the same time.<\/p>\r\n\r\n\r\n\r\nThat is not how classical computing works.<\/p>\r\n\r\n\r\n\r\n
Quantum computing also requires a different physical device as hardware.<\/p>\r\n\r\n\r\n\r\n
One approach is to work in supercooled temperature environment where superconductivity occurs in certain materials, and the electrons, who at higher temperatures are disorganized and feel resistance, now instead pair up (and act as bosons!) and feel no resistance.<\/p>\r\n\r\n\r\n\r\n
If a circular coil made of this material is supercooled, then these electrons can circulate (clockwise or anti-clockwise) forever if needed, and now, this is the key:<\/em><\/p>\r\n\r\n\r\n\r\n\u00a0we can (using microwave pulse) make this supercooled coil behave like a qubit, that is, as if the electron pair is circulating both clockwise and anti-clockwise at the same time!<\/p>\r\n\r\n\r\n\r\n
The physical device needs to be able to \u201chold\u201d this superposition state for a period of time.<\/p>\r\n\r\n\r\n\r\n
Quantum algorithms are conceived with this new conceptual model with qubits to run on quantum hardware.<\/p>\r\n\r\n\r\n\r\n
This is not your father\u2019s Turing-machine!<\/p>\r\n\r\n\r\n\r\n
Quantum algorithms take a classical input (in bits), transform that to an initial superposition state<\/em>, a qubit, then provide a series of steps that act on superposition states and transform to other super position states, and so on, until the very last step, when the final super position state<\/em> (of the qubit) is \u201cmeasured\u201d and it collapses<\/em> to a classical state, into a bit, which is then delivered as an output (that is classical).<\/p>\r\n\r\n\r\n\r\nThe physical device needs to be able to execute the instructions of the quantum algorithm while maintaining the superposition states, at all times, until the final measurement.<\/p>\r\n\r\n\r\n\r\n
It is really, really difficult to \u201chold\u201d a superposition state as it is so fragile that any contact with the environment makes it collapse.<\/p>\r\n\r\n\r\n\r\n
Software? Not surprisingly, new programming languages are cropping up that are tailored to “writing” quantum algorithms that quantum hardware can understand.<\/p>\r\n\r\n\r\n\r\n
Welcome to the 21st<\/sup>Century!\u00a0<\/p>\r\n","protected":false},"excerpt":{"rendered":"A gentle introduction to classical and quantum computing for MBA type audience.<\/p>\n","protected":false},"author":1,"featured_media":2994,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[331,842,493,491,492,490],"_links":{"self":[{"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/posts\/2991"}],"collection":[{"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/comments?post=2991"}],"version-history":[{"count":19,"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/posts\/2991\/revisions"}],"predecessor-version":[{"id":6662,"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/posts\/2991\/revisions\/6662"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/media\/2994"}],"wp:attachment":[{"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/media?parent=2991"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/categories?post=2991"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.myamplelife.com\/wp\/wp-json\/wp\/v2\/tags?post=2991"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}