quantum computer, device that employs properties described by quantum mechanics to enhance computations.
As early as 1959 the American physicist and Nobel laureate Richard Feynman noted that, as electronic components begin to reach microscopic scales, effects predicted by quantum mechanics occurwhich, he suggested, might be exploited in the design of more powerful computers. In particular, quantum researchers hope to harness a phenomenon known as superposition. In the quantum mechanical world, objects do not necessarily have clearly defined states, as demonstrated by the famous experiment in which a single photon of light passing through a screen with two small slits will produce a wavelike interference pattern, or superposition of all available paths. (See wave-particle duality.) However, when one slit is closedor a detector is used to determine which slit the photon passed throughthe interference pattern disappears. In consequence, a quantum system exists in all possible states before a measurement collapses the system into one state. Harnessing this phenomenon in a computer promises to expand computational power greatly. A traditional digital computer employs binary digits, or bits, that can be in one of two states, represented as 0 and 1; thus, for example, a 4-bit computer register can hold any one of 16 (24) possible numbers. In contrast, a quantum bit (qubit) exists in a wavelike superposition of values from 0 to 1; thus, for example, a 4-qubit computer register can hold 16 different numbers simultaneously. In theory, a quantum computer can therefore operate on a great many values in parallel, so that a 30-qubit quantum computer would be comparable to a digital computer capable of performing 10 trillion floating-point operations per second (TFLOPS)comparable to the speed of the fastest supercomputers.
During the 1980s and 90s the theory of quantum computers advanced considerably beyond Feynmans early speculations. In 1985 David Deutsch of the University of Oxford described the construction of quantum logic gates for a universal quantum computer, and in 1994 Peter Shor of AT&T devised an algorithm to factor numbers with a quantum computer that would require as few as six qubits (although many more qubits would be necessary for factoring large numbers in a reasonable time). When a practical quantum computer is built, it will break current encryption schemes based on multiplying two large primes; in compensation, quantum mechanical effects offer a new method of secure communication known as quantum encryption. However, actually building a useful quantum computer has proved difficult. Although the potential of quantum computers is enormous, the requirements are equally stringent. A quantum computer must maintain coherence between its qubits (known as quantum entanglement) long enough to perform an algorithm; because of nearly inevitable interactions with the environment (decoherence), practical methods of detecting and correcting errors need to be devised; and, finally, since measuring a quantum system disturbs its state, reliable methods of extracting information must be developed.
Plans for building quantum computers have been proposed; although several demonstrate the fundamental principles, none is beyond the experimental stage. Three of the most promising approaches are presented below: nuclear magnetic resonance (NMR), ion traps, and quantum dots.
In 1998 Isaac Chuang of the Los Alamos National Laboratory, Neil Gershenfeld of the Massachusetts Institute of Technology (MIT), and Mark Kubinec of the University of California at Berkeley created the first quantum computer (2-qubit) that could be loaded with data and output a solution. Although their system was coherent for only a few nanoseconds and trivial from the perspective of solving meaningful problems, it demonstrated the principles of quantum computation. Rather than trying to isolate a few subatomic particles, they dissolved a large number of chloroform molecules (CHCL3) in water at room temperature and applied a magnetic field to orient the spins of the carbon and hydrogen nuclei in the chloroform. (Because ordinary carbon has no magnetic spin, their solution used an isotope, carbon-13.) A spin parallel to the external magnetic field could then be interpreted as a 1 and an antiparallel spin as 0, and the hydrogen nuclei and carbon-13 nuclei could be treated collectively as a 2-qubit system. In addition to the external magnetic field, radio frequency pulses were applied to cause spin states to flip, thereby creating superimposed parallel and antiparallel states. Further pulses were applied to execute a simple algorithm and to examine the systems final state. This type of quantum computer can be extended by using molecules with more individually addressable nuclei. In fact, in March 2000 Emanuel Knill, Raymond Laflamme, and Rudy Martinez of Los Alamos and Ching-Hua Tseng of MIT announced that they had created a 7-qubit quantum computer using trans-crotonic acid. However, many researchers are skeptical about extending magnetic techniques much beyond 10 to 15 qubits because of diminishing coherence among the nuclei.
Just one week before the announcement of a 7-qubit quantum computer, physicist David Wineland and colleagues at the U.S. National Institute for Standards and Technology (NIST) announced that they had created a 4-qubit quantum computer by entangling four ionized beryllium atoms using an electromagnetic trap. After confining the ions in a linear arrangement, a laser cooled the particles almost to absolute zero and synchronized their spin states. Finally, a laser was used to entangle the particles, creating a superposition of both spin-up and spin-down states simultaneously for all four ions. Again, this approach demonstrated basic principles of quantum computing, but scaling up the technique to practical dimensions remains problematic.
Quantum computers based on semiconductor technology are yet another possibility. In a common approach a discrete number of free electrons (qubits) reside within extremely small regions, known as quantum dots, and in one of two spin states, interpreted as 0 and 1. Although prone to decoherence, such quantum computers build on well-established, solid-state techniques and offer the prospect of readily applying integrated circuit scaling technology. In addition, large ensembles of identical quantum dots could potentially be manufactured on a single silicon chip. The chip operates in an external magnetic field that controls electron spin states, while neighbouring electrons are weakly coupled (entangled) through quantum mechanical effects. An array of superimposed wire electrodes allows individual quantum dots to be addressed, algorithms executed, and results deduced. Such a system necessarily must be operated at temperatures near absolute zero to minimize environmental decoherence, but it has the potential to incorporate very large numbers of qubits.
Read the original post:
Quantum computer | Description & Facts | Britannica
- Time Crystals Could be the Key to the First Quantum Computer - TrendinTech [Last Updated On: May 3rd, 2017] [Originally Added On: May 3rd, 2017]
- The Quantum Computer Revolution Is Closer Than You May Think - National Review [Last Updated On: May 3rd, 2017] [Originally Added On: May 3rd, 2017]
- Chinese scientists build world's first quantum computing machine - India Today [Last Updated On: May 3rd, 2017] [Originally Added On: May 3rd, 2017]
- Quantum Computing | D-Wave Systems [Last Updated On: May 3rd, 2017] [Originally Added On: May 3rd, 2017]
- Quantum computing utilizes 3D crystals - Johns Hopkins News-Letter [Last Updated On: May 4th, 2017] [Originally Added On: May 4th, 2017]
- Quantum Computing and What All Good IT Managers Should Know - TrendinTech [Last Updated On: May 4th, 2017] [Originally Added On: May 4th, 2017]
- World's First Quantum Computer Made By China 24000 Times Faster Than International Counterparts - Fossbytes [Last Updated On: May 4th, 2017] [Originally Added On: May 4th, 2017]
- China adds a quantum computer to high-performance computing arsenal - PCWorld [Last Updated On: May 6th, 2017] [Originally Added On: May 6th, 2017]
- Quantum computing: A simple introduction - Explain that Stuff [Last Updated On: May 6th, 2017] [Originally Added On: May 6th, 2017]
- What is Quantum Computing? Webopedia Definition [Last Updated On: May 6th, 2017] [Originally Added On: May 6th, 2017]
- Quantum Computing Market Forecast 2017-2022 | Market ... [Last Updated On: May 6th, 2017] [Originally Added On: May 6th, 2017]
- China hits milestone in developing quantum computer - South China Morning Post [Last Updated On: May 8th, 2017] [Originally Added On: May 8th, 2017]
- China builds five qubit quantum computer sampling and will scale to 20 qubits by end of this year and could any beat ... - Next Big Future [Last Updated On: May 8th, 2017] [Originally Added On: May 8th, 2017]
- Five Ways Quantum Computing Will Change the Way We Think ... - PR Newswire (press release) [Last Updated On: May 8th, 2017] [Originally Added On: May 8th, 2017]
- Quantum Computing Demands a Whole New Kind of Programmer - Singularity Hub [Last Updated On: May 9th, 2017] [Originally Added On: May 9th, 2017]
- New materials bring quantum computing closer to reality - Phys.org - Phys.Org [Last Updated On: May 9th, 2017] [Originally Added On: May 9th, 2017]
- Researchers Invent Nanoscale 'Refrigerator' for Quantum ... - Sci-News.com [Last Updated On: May 11th, 2017] [Originally Added On: May 11th, 2017]
- China's New Type of Quantum Computing Device, Built Inside a Diamond - TrendinTech [Last Updated On: May 11th, 2017] [Originally Added On: May 11th, 2017]
- Molecular magnets closer to application in quantum computing - Next Big Future [Last Updated On: May 11th, 2017] [Originally Added On: May 11th, 2017]
- New Materials Could Make Quantum Computers More Practical - Tom's Hardware [Last Updated On: May 11th, 2017] [Originally Added On: May 11th, 2017]
- Home News Computer Europe Takes Quantum Computing to the Next Level With this Billion Euro... - TrendinTech [Last Updated On: May 13th, 2017] [Originally Added On: May 13th, 2017]
- Researchers seek to advance quantum computing - The Stanford Daily [Last Updated On: May 13th, 2017] [Originally Added On: May 13th, 2017]
- quantum computing - WIRED UK [Last Updated On: May 13th, 2017] [Originally Added On: May 13th, 2017]
- Scientists Invent Nanoscale Refrigerator For Quantum Computers - Wall Street Pit [Last Updated On: May 14th, 2017] [Originally Added On: May 14th, 2017]
- D-Wave Closes $50M Facility to Fund Next Generation of Quantum Computers - Marketwired (press release) [Last Updated On: May 17th, 2017] [Originally Added On: May 17th, 2017]
- Quantum Computers Sound Great, But Who's Going to Program Them? - TrendinTech [Last Updated On: May 17th, 2017] [Originally Added On: May 17th, 2017]
- Quantum Computing Could Use Graphene To Create Stable Qubits - International Business Times [Last Updated On: May 18th, 2017] [Originally Added On: May 18th, 2017]
- Bigger is better: Quantum volume expresses computer's limit - Ars Technica [Last Updated On: May 18th, 2017] [Originally Added On: May 18th, 2017]
- IBM's Newest Quantum Computing Processors Have Triple the Qubits of Their Last - Futurism [Last Updated On: May 18th, 2017] [Originally Added On: May 18th, 2017]
- It's time to decide how quantum computing will help your business - Techworld Australia [Last Updated On: May 20th, 2017] [Originally Added On: May 20th, 2017]
- IBM makes a leap in quantum computing power - PCWorld [Last Updated On: May 20th, 2017] [Originally Added On: May 20th, 2017]
- IBM scientists demonstrate ballistic nanowire connections, a potential future key component for quantum computing - Phys.Org [Last Updated On: May 20th, 2017] [Originally Added On: May 20th, 2017]
- The route to high-speed quantum computing is paved with error - Ars Technica UK [Last Updated On: May 20th, 2017] [Originally Added On: May 20th, 2017]
- IBM makes leap in quantum computing power - ITworld [Last Updated On: May 22nd, 2017] [Originally Added On: May 22nd, 2017]
- Researchers push forward quantum computing research - The ... - Economic Times [Last Updated On: May 22nd, 2017] [Originally Added On: May 22nd, 2017]
- Quantum Computing Research Given a Boost by Stanford Team - News18 [Last Updated On: May 22nd, 2017] [Originally Added On: May 22nd, 2017]
- US playing catch-up in quantum computing - The Register-Guard [Last Updated On: May 22nd, 2017] [Originally Added On: May 22nd, 2017]
- Stanford researchers push forward quantum computing research ... - The Indian Express [Last Updated On: May 23rd, 2017] [Originally Added On: May 23rd, 2017]
- NASA Scientist Eleanor Rieffel to give a talk on quantum computing - Chapman University: Happenings (blog) [Last Updated On: May 23rd, 2017] [Originally Added On: May 23rd, 2017]
- Graphene Just Brought Us One Step Closer to Practical Quantum Computers - Futurism [Last Updated On: May 23rd, 2017] [Originally Added On: May 23rd, 2017]
- IBM Q Offers Quantum Computing as a Service - The Merkle [Last Updated On: May 23rd, 2017] [Originally Added On: May 23rd, 2017]
- How quantum computing increases cybersecurity risks | Network ... - Network World [Last Updated On: May 23rd, 2017] [Originally Added On: May 23rd, 2017]
- Quantum Computing Is Going Commercial With the Potential ... [Last Updated On: May 23rd, 2017] [Originally Added On: May 23rd, 2017]
- Is the US falling behind in the race for quantum computing? - AroundtheO [Last Updated On: May 26th, 2017] [Originally Added On: May 26th, 2017]
- Quantum computing, election pledges and a thief who made science history - Nature.com [Last Updated On: May 26th, 2017] [Originally Added On: May 26th, 2017]
- Top 5: Things to know about quantum computers - TechRepublic [Last Updated On: May 26th, 2017] [Originally Added On: May 26th, 2017]
- Google Plans to Demonstrate the Supremacy of Quantum ... - IEEE Spectrum [Last Updated On: May 26th, 2017] [Originally Added On: May 26th, 2017]
- Quantum Computing Is Real, and D-Wave Just Open ... - WIRED [Last Updated On: May 26th, 2017] [Originally Added On: May 26th, 2017]
- IBM to Sell Use of Its New 17-Qubit Quantum Computer over the Cloud - All About Circuits [Last Updated On: May 28th, 2017] [Originally Added On: May 28th, 2017]
- Doped Diamonds Push Practical Quantum Computing Closer to Reality - Motherboard [Last Updated On: May 28th, 2017] [Originally Added On: May 28th, 2017]
- For more advanced computing, technology needs to make a ... - CIO Dive [Last Updated On: May 30th, 2017] [Originally Added On: May 30th, 2017]
- Microsoft, Purdue Extend Quantum Computing Partnership To Create More Stable Qubits - Tom's Hardware [Last Updated On: May 30th, 2017] [Originally Added On: May 30th, 2017]
- AI and Quantum Computers Are Our Best Weapons Against Cyber Criminals - Futurism [Last Updated On: May 30th, 2017] [Originally Added On: May 30th, 2017]
- Toward mass-producible quantum computers | MIT News - MIT News [Last Updated On: June 1st, 2017] [Originally Added On: June 1st, 2017]
- Purdue, Microsoft Partner On Quantum Computing Research | WBAA - WBAA [Last Updated On: June 1st, 2017] [Originally Added On: June 1st, 2017]
- Tektronix AWG Pulls Test into Era of Quantum Computing - Electronic Design [Last Updated On: June 1st, 2017] [Originally Added On: June 1st, 2017]
- Telstra just wants a quantum computer to offer as-a-service - ZDNet [Last Updated On: June 1st, 2017] [Originally Added On: June 1st, 2017]
- D-Wave partners with U of T to move quantum computing along - Financial Post [Last Updated On: June 1st, 2017] [Originally Added On: June 1st, 2017]
- MIT Just Unveiled A Technique to Mass Produce Quantum Computers - Futurism [Last Updated On: June 1st, 2017] [Originally Added On: June 1st, 2017]
- Here's how we can achieve mass-produced quantum computers ... - ScienceAlert [Last Updated On: June 1st, 2017] [Originally Added On: June 1st, 2017]
- Research collaborative pursues advanced quantum computing - Phys.Org [Last Updated On: June 1st, 2017] [Originally Added On: June 1st, 2017]
- Team develops first blockchain that can't be hacked by quantum computer - Siliconrepublic.com [Last Updated On: June 3rd, 2017] [Originally Added On: June 3rd, 2017]
- Quantum computers to drive customer insights, says CBA CIO - CIO - CIO Australia [Last Updated On: June 6th, 2017] [Originally Added On: June 6th, 2017]
- FinDEVr London: Preparing for the Dark Side of Quantum Computing - GlobeNewswire (press release) [Last Updated On: June 8th, 2017] [Originally Added On: June 8th, 2017]
- Scientists May Have Found a Way to Combat Quantum Computer Blockchain Hacking - Futurism [Last Updated On: June 9th, 2017] [Originally Added On: June 9th, 2017]
- Purdue, Microsoft to Collaborate on Quantum Computer - Photonics.com [Last Updated On: June 9th, 2017] [Originally Added On: June 9th, 2017]
- From the Abacus to Supercomputers to Quantum Computers - Duke Today [Last Updated On: June 12th, 2017] [Originally Added On: June 12th, 2017]
- Microsoft and Purdue work on scalable topological quantum computer - Next Big Future [Last Updated On: June 12th, 2017] [Originally Added On: June 12th, 2017]
- Are Enterprises Ready to Take a Quantum Leap? - IT Business Edge [Last Updated On: June 12th, 2017] [Originally Added On: June 12th, 2017]
- A Hybrid of Quantum Computing and Machine Learning Is Spawning New Ventures - IEEE Spectrum [Last Updated On: June 14th, 2017] [Originally Added On: June 14th, 2017]
- The Machine of Tomorrow Today: Quantum Computing on the Verge - Bloomberg [Last Updated On: June 14th, 2017] [Originally Added On: June 14th, 2017]
- KPN CISO details Quantum computing attack dangers - Mobile World Live [Last Updated On: June 15th, 2017] [Originally Added On: June 15th, 2017]
- Accenture, Biogen, 1QBit Launch Quantum Computing App to ... - HIT Consultant [Last Updated On: June 15th, 2017] [Originally Added On: June 15th, 2017]
- Angry Birds, qubits and big ideas: Quantum computing is tantalisingly close - The Australian Financial Review [Last Updated On: June 15th, 2017] [Originally Added On: June 15th, 2017]
- Consortium Applies Quantum Computing to Drug Discovery for Neurological Diseases - Drug Discovery & Development [Last Updated On: June 15th, 2017] [Originally Added On: June 15th, 2017]
- Accenture, 1QBit partner for drug discovery through quantum computing - ZDNet [Last Updated On: June 15th, 2017] [Originally Added On: June 15th, 2017]
- How to get ahead in quantum machine learning AND attract Goldman Sachs - eFinancialCareers [Last Updated On: June 15th, 2017] [Originally Added On: June 15th, 2017]
- Quantum computing, the machines of tomorrow - The Japan Times [Last Updated On: June 16th, 2017] [Originally Added On: June 16th, 2017]
- Toward optical quantum computing - MIT News [Last Updated On: June 17th, 2017] [Originally Added On: June 17th, 2017]
- Its time to decide how quantum computing will help your ... [Last Updated On: June 18th, 2017] [Originally Added On: June 18th, 2017]