Scientists engineered a high-tech computer that can run several
simple programs by harnessing the relationships between tiny particles,
or quantum mechanics, according to a new report Wednesday.
The work represents a leap in the field of so-called quantum computers, which store information differently than traditional machines, computing experts said.
Classical computers use binary bits of information, whose values alternate between 0 and 1, to store data. Quantum computers use smaller units—“qubits”—which can simultaneously be 0 and 1. That duality underpins their rapidity and potential supremacy over conventional devices like laptops and servers.
The new device combines magnets, lasers and five individual ions, or charged atoms, trapped in single file. Each atom represents singular qubits. The team of researchers, at the University of Maryland in College Park, used the mechanism to run three different basic algorithms, including a primitive version of the algorithm that underlies encryption technology.
“It’s wonderful work,” said Krysta Svore, a research manager at Microsoft Research, Microsoft Corp. ’s experimental arm, who wasn’t involved with the study.
Government organizations, academic labs and companies like Alphabet Inc. subsidiary Google, Microsoft and International Business Machines Corp. believe quantum machines will facilitate advances in materials science, chemistry, space exploration and artificial intelligence. They are investing millions on developing so-called universal quantum computers that could execute any program without tweaking the hardware on which that software runs.
The new prototype, described in the journal Nature, is a step in that direction—“a very clear demonstration of flexible programmability and universality on a single hardware platform,” said Mark Saffman, a University of Wisconsin-Madison physicist who wasn’t involved in the work.
The lead researcher, Chris Monroe, is using the technology to launch a startup dubbed ionQ Inc., according to the paper’s first author, graduate student Shantanu Debnath.
Previous attempts have made strides toward, but haven’t quite achieved, such versatility, said Daniel Lidar, the director of the University of Southern California Center for Quantum Information Science & Technology in Los Angeles.
To run their algorithms, the researchers devised the equivalent of a quantum-scale laser-light show. They split a single laser beam and precisely varied the times and intensities at which each mini-ray struck atomic qubits. Their ensuing vibrations can entangle any pair such that they behave like a unit. Such particle pas-de-deux give quantum machines their speed.
Depending on the operation, qubits light up a certain way; a detector sees that fluorescence and uses it to read the information the qubits hold.
Simple calculations had an accuracy of 98%. For more complex ones, like the encryption algorithm, accuracy plummeted to roughly 60%. In the quantum world, scientists aim for precisions higher than 99%. At that level, they can start harnessing quantum mechanics to correct errors that naturally build up in quantum systems, an important hurdle to making them workable.
They haven’t yet shown they can do that, said Hartmut Neven, a director of engineering at Google specializing in quantum computing. Mr. Debnath says they are tackling the problem.
The researchers must also prove they can build a reliable system bigger than five qubits, said Dr. Saffman and others. Such scalability is among the biggest quandaries in quantum computing. To solve commercially interesting problems that can’t be cracked in a timely manner with classical computers, experts estimate somewhere between hundreds to millions of qubits will be necessary, depending on complexity. Most experimental systems have handled only a handful.
D-Wave Systems Inc. has a 1,152-qubit system, though scientists have called into question the reliability and “quantum-ness.” D-Wave stands by the quality of its product, which it says is used by companies like Lockheed Martin and Google, according to CEO Vern Brownell.
There is disagreement over what flavor of qubits will ultimately dominate: individual trapped ions in a line, like the ones in the new study, or superconducting qubits, which are essentially a collection of atoms acting together as a quantum unit. Commercial companies like Google and IBM prefer superconducting qubits because they are faster and can be manufactured similarly to conventional chips. Trapped-ion qubits are more reliable, but may be difficult to scale. (Microsoft is going after an altogether different approach.)
Isaac Chuang, a quantum-information scientist at the Massachusetts Institute of Technology, thinks it is likely future quantum machines will fuse several technologies. Such hybrids are already emerging. In June, Google published a study, also in Nature, describing a prototype that reliably merged two architectures. That machine was also regarded as a step toward a multipurpose quantum computer.
Write to Daniela Hernandez at daniela.hernandez@wsj.com
Source:http://www.wsj.com/articles/scientists-harness-quantum-physics-to-build-a-programmable-computer-1470243605
The work represents a leap in the field of so-called quantum computers, which store information differently than traditional machines, computing experts said.
Classical computers use binary bits of information, whose values alternate between 0 and 1, to store data. Quantum computers use smaller units—“qubits”—which can simultaneously be 0 and 1. That duality underpins their rapidity and potential supremacy over conventional devices like laptops and servers.
The new device combines magnets, lasers and five individual ions, or charged atoms, trapped in single file. Each atom represents singular qubits. The team of researchers, at the University of Maryland in College Park, used the mechanism to run three different basic algorithms, including a primitive version of the algorithm that underlies encryption technology.
“It’s wonderful work,” said Krysta Svore, a research manager at Microsoft Research, Microsoft Corp. ’s experimental arm, who wasn’t involved with the study.
Government organizations, academic labs and companies like Alphabet Inc. subsidiary Google, Microsoft and International Business Machines Corp. believe quantum machines will facilitate advances in materials science, chemistry, space exploration and artificial intelligence. They are investing millions on developing so-called universal quantum computers that could execute any program without tweaking the hardware on which that software runs.
The new prototype, described in the journal Nature, is a step in that direction—“a very clear demonstration of flexible programmability and universality on a single hardware platform,” said Mark Saffman, a University of Wisconsin-Madison physicist who wasn’t involved in the work.
The lead researcher, Chris Monroe, is using the technology to launch a startup dubbed ionQ Inc., according to the paper’s first author, graduate student Shantanu Debnath.
Previous attempts have made strides toward, but haven’t quite achieved, such versatility, said Daniel Lidar, the director of the University of Southern California Center for Quantum Information Science & Technology in Los Angeles.
To run their algorithms, the researchers devised the equivalent of a quantum-scale laser-light show. They split a single laser beam and precisely varied the times and intensities at which each mini-ray struck atomic qubits. Their ensuing vibrations can entangle any pair such that they behave like a unit. Such particle pas-de-deux give quantum machines their speed.
Depending on the operation, qubits light up a certain way; a detector sees that fluorescence and uses it to read the information the qubits hold.
Simple calculations had an accuracy of 98%. For more complex ones, like the encryption algorithm, accuracy plummeted to roughly 60%. In the quantum world, scientists aim for precisions higher than 99%. At that level, they can start harnessing quantum mechanics to correct errors that naturally build up in quantum systems, an important hurdle to making them workable.
They haven’t yet shown they can do that, said Hartmut Neven, a director of engineering at Google specializing in quantum computing. Mr. Debnath says they are tackling the problem.
The researchers must also prove they can build a reliable system bigger than five qubits, said Dr. Saffman and others. Such scalability is among the biggest quandaries in quantum computing. To solve commercially interesting problems that can’t be cracked in a timely manner with classical computers, experts estimate somewhere between hundreds to millions of qubits will be necessary, depending on complexity. Most experimental systems have handled only a handful.
D-Wave Systems Inc. has a 1,152-qubit system, though scientists have called into question the reliability and “quantum-ness.” D-Wave stands by the quality of its product, which it says is used by companies like Lockheed Martin and Google, according to CEO Vern Brownell.
There is disagreement over what flavor of qubits will ultimately dominate: individual trapped ions in a line, like the ones in the new study, or superconducting qubits, which are essentially a collection of atoms acting together as a quantum unit. Commercial companies like Google and IBM prefer superconducting qubits because they are faster and can be manufactured similarly to conventional chips. Trapped-ion qubits are more reliable, but may be difficult to scale. (Microsoft is going after an altogether different approach.)
Isaac Chuang, a quantum-information scientist at the Massachusetts Institute of Technology, thinks it is likely future quantum machines will fuse several technologies. Such hybrids are already emerging. In June, Google published a study, also in Nature, describing a prototype that reliably merged two architectures. That machine was also regarded as a step toward a multipurpose quantum computer.
Write to Daniela Hernandez at daniela.hernandez@wsj.com
Source:http://www.wsj.com/articles/scientists-harness-quantum-physics-to-build-a-programmable-computer-1470243605
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