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Quantum Information Research at NIST: Goals and Vision What Good Is Quantum Information?
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Quantum computing offers the possibility of parallel processing on a grand scale. Unlike switches in today’s computer chips, which are either on or off, qubits can be in superpositions of both on and off at the same time, and entangled so that their properties are correlated even if the qubits are moved apart. Properties like this could enable a quantum computer to solve certain problems in an exponentially shorter time than today’s computers. Researchers often point out that, for specific classes of problems, a quantum computer with 300 qubits potentially has more processing power than a classical computer containing as many bits as there are particles in the universe.
For instance, the security of today’s most common cryptographic systems relies on the difficulty of “factoring” large numbers—figuring out which smaller prime numbers, when multiplied together, equal the large number. Today’s computers cannot factor large numbers in reasonable amounts of time. A network of classical computers (with trillions of bits and trillions of operations per second) would need to operate for years to factor a 200-digit number, whereas a relatively small quantum computer consisting of 100,000 qubits might do it in just a few minutes or less.
Applications may extend far beyond breaking today’s best encryption codes. Many physicists, computer scientists, and mathematicians are excited about quantum computing because they believe that new insights needed to build such a machine will lead to important discoveries about information processing and, more generally, about the universe by solving problems that cannot even be attempted today. New tools developed for quantum information science may help unlock secrets of nature, using quantum mechanics to explain how literally everything works. But harnessing all this potential is extremely difficult. Researchers need to find ways of controlling and measuring delicate quantum states while minimizing electronic “noise” and ensuing computational errors. The challenge becomes greater as the number of qubits grows. In addition, to make full use of a quantum computer, scientists must design new software programs that can take advantage of the unusual quantum properties. These software packages must be far more efficient than conventional computer programs. Many basic components and tools of quantum computing already have been demonstrated. These experiments generally require a roomful of equipment. Several ions (charged atoms) in a trap, for example, need to be kept in a housing 0.03 cubic meters (1 cubic foot) in size and manipulated with a laser system spread over two large optical tables, controlled by huge racks of electronics. Someday, scientists might find a way to squeeze as many as 1 billion neutral atom qubits into a processor smaller than a sugar cube. But it is expected to take years, perhaps decades, to build a useful quantum computer, regardless of the design. NIST is pursuing three separate approaches to quantum processing: trapped ions, neutral atoms, and “artificial atoms” made of superconducting electrical circuits. While other technical approaches are being pursued at other institutions, NIST researchers believe these three types of qubits provide the best near- term possibilities for breakthroughs while also having potential applications to other NIST mission activities. Because this work is very long term, these are largely independent projects exploring potential quantum computing technologies. However, knowledge of complex quantum systems obtained from one or more of these projects may contribute insights and help create new paradigms for the others.
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Date
created: 4/11/06
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