Quantum Computing  

Quantum computing promises to be the next major technology with the potential to drive a new era of innovation across industries. Following on the success of competitors like D-Wave, IBM has announced that it too will begin commercializing quantum based computer systems.

Functional quantum computers are an entirely new paradigm of computing, and so far have only had limited implementation in the marketplace. IBM Q systems hopes to change that. The computing company will design a new class of computers that make use of quantum computers and aims to sell them commercially in a very short time.

"Our goal is to provide businesses and organizations with access to a new realm of computational power, before unachievable, to solve real-world and societal problems."

IBM intends to build their IBM Q systems with around 50 qubits in the next few years to demonstrate capabilities beyond today’s classical systems, and will collaborate with key industry partners to develop applications that exploit the quantum speedup of the systems. Potential applications include medicine and materials discovery, supply chain and logistics, financial services, artificial intelligence and cloud security.

Due to the exponential power of quantum computers, it is postulated that a universal quantum system with just 50 qubits may be able to perform certain complex calculations at a rate that today’s top multi-Petaflop supercomputers can’t yet produce.

IBM has demonstrated prototype systems that use quantum effects in small-scale demonstrations. They have taken advantage of effects like superpositioning, where trapped electrons can exist in two states at the same time, and used this behaviour to allow them to work in far more complex ways than the 1s and 0s that are used in today's computers.

The company has also released a new application programming interface (API) for the IBM Quantum Experience that enables developers and programmers to build interfaces between its existing five qubit, IBM Cloud-based quantum computer and classical computers.

One of the first and most promising applications for the new quantum computer system will be in the simulation of chemistry. Even for simple molecules like caffeine, the number of quantum states in the molecule can be astoundingly large – so large that all the conventional computing memory and processing power scientists could ever build could not handle the problem.

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"The universal quantum computers IBM has worked toward in more than 35 years of research are the most powerful and general class of quantum computers," writes Dario Gil, Vice President, Science and Solutions, IBM Research. "Their mojo comes from the quantum bit, or qubit, which leverages quantum effects that are not visible in our daily lives, to explore an exponentially more-powerful computational space, to help solve certain problems that we could not otherwise solve."

"Our goal is to provide businesses and organizations with access to a new realm of computational power, before unachievable, to solve real-world and societal problems," Gil writes on the company's blog.

IBM has been collaborating and engaging with developers, programmers and university partners for the development and evolution of IBM’s quantum computing systems. Since its launch less than a year ago, about 40,000 users have run over 275,000 experiments on the IBM Quantum Experience API. So far, 15 third-party research papers have been posted to arXiv with five published in leading journals based on experiments run on the Quantum Experience.

IBM has worked with academic institutions, such as MIT, the  Institute for Quantum Computing at the University of Waterloo, and École polytechnique fédérale de Lausanne (EPFL)
to leverage the IBM Quantum Experience as an educational tool for students.

Quantum computers are projected to have the capabilities to tackle problems that are currently seen as too complex and exponential in nature for classical computers. The promise of these systems is that they will deliver solutions to important problems where patterns cannot be seen and the number of possibilities that you need to explore to get to the answer are too enormous ever to be processed by classical computers.

SOURCE  IBM

By  33rd Square

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Quantum Computers  

Researchers have developed a new quantum computer module, which is the first method allowing fully programmable and reconfigurable quantum bits. The qubits are dynamically connected from the outside with patterns of laser beams, any algorithm can be run through software without modifying the base hardware.

In a paper published recently in the journal Nature, researchers show how they have introduced the first fully programmable and reconfigurable quantum computer module. The new device, called a module because of its potential to connect with copies of itself, takes advantage of the unique properties offered by trapped ions to run any algorithm on five quantum bits, or qubits—the fundamental unit of information in a quantum computer.

“For any computer to be useful, the user should not be required to know what’s inside,” Christopher Monroe, a Fellow of the Joint Quantum Institute and the Joint Center for Quantum Information and Computer Science at the University of Maryland says. “Very few people care what their iPhone is actually doing at the physical level. Our experiment brings high-quality quantum bits up to a higher level of functionality by allowing them to be programmed and reconfigured in software.”

"This work is at the frontier of quantum computing, and it’s helping to lay a foundation and bring practical quantum computing closer to being a reality."

So far, other researchers have created small and functional quantum computers, by combining a small number of atoms, electrons or superconducting junctions. This work has demonstrated quantum effects and run simple quantum algorithms—small programs dedicated to solving discrete problems.

Such quantum devices are often hard-wired to run one program or limited to fixed patterns of interactions between their quantum components. Making a quantum computer that can run arbitrary algorithms requires the right kind of physical system and a specific set of programming tools. Atomic ions, confined by fields from nearby electrodes, are among the most promising platforms for meeting these needs.

The new quantum computer module builds on decades of research into trapping and controlling ions. Using standard techniques but also introducing novel methods for control and measurement. This includes manipulating many ions at once using an array of tightly-focused laser beams, as well as dedicated detection channels that watch for the glow of each ion.

The scientists tested their module on small instances of three well established quantum computer problems. With the flexibility to test the module on a variety of problems, Shantanu Debnath, a graduate student at JQI and the paper’s lead author says, “By directly connecting any pair of qubits, we can reconfigure the system to implement any algorithm. While it’s just five qubits, we know how to apply the same technique to much larger collections.”

Key to the module working, is something that’s not even quantum: A database stores the best shapes for the laser pulses that drive quantum logic gates, the building blocks of quantum algorithms. Those shapes are calculated ahead of time using a regular computer, and the module uses software to translate an algorithm into the pulses in the database.

Every quantum algorithm consists of three basic ingredients. First, the qubits are prepared in a particular state; second, they undergo a sequence of quantum logic gates; and last, a quantum measurement extracts the algorithm’s output.

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The module performs these tasks using different colors of laser light. One color prepares the ions using a technique called optical pumping, in which each qubit is illuminated until it sits in the proper quantum energy state. The same laser helps read out the quantum state of each atomic ion at the end of the process. In between, a separate laser strikes the ions to drive quantum logic gates.

These gates are like the switches and transistors that power ordinary computers. Here, lasers push on the ions and couple their internal qubit information to their motion, allowing any two ions in the module to interact via their strong electrical repulsion. Two ions from across the chain notice each other through this electrical interaction, just as raising and releasing one ball in a Newton’s cradle transfers energy to the other side.

To test the module, the team ran three different quantum algorithms, including a demonstration of a Quantum Fourier Transform (QFT), which finds how often a given mathematical function repeats. It is a key piece in Shor’s quantum factoring algorithm, which would break some of the most widely-used security standards on the internet if run on a big enough quantum computer.

The researchers think that eventually more qubits—perhaps as many as 100—could be added to their quantum computer module. It is also possible to link separate modules together, either by physically moving the ions or by using photons to carry information between them.

According to Jean Cottam Allen, a program director in the National Science Foundation’s physics division. “This work is at the frontier of quantum computing, and it’s helping to lay a foundation and bring practical quantum computing closer to being a reality.”

SOURCE  Joint Quantum Institute

By  33rd Square

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Quantum Computers  

Researchers have reported an important step toward practical quantum computers, with a paper describing a prototype chip that can trap ions in an electric field and, with built-in optics, direct laser light toward each of them.

Researchers at MIT have designed and built a suite of on-chip optical components that can channel laser light toward individual ions.The work has been published recently in Nature Nanotechnology, and could be an important step toward practical quantum computers. The paper describes a prototype chip that can trap ions in an electric field and, with built-in optics, direct laser light toward each of them.

Jeremy Sage, who together with John Chiaverini, and their colleagues Colin Bruzewicz and Robert McConnell retooled their surface trap to accommodate the integrated optics without compromising its performance. Together, both groups designed and executed the experiments to test the new system.

“If you look at the traditional assembly, it’s a barrel that has a vacuum inside it, and inside that is this cage that’s trapping the ions. Then there’s basically an entire laboratory of external optics that are guiding the laser beams to the assembly of ions,” says Rajeev Ram, an MIT professor of electrical engineering and one of the senior authors on the paper. “Our vision is to take that external laboratory and miniaturize much of it onto a chip.”

“Typically, for surface electrode traps, the laser beam is coming from an optical table and entering this system, so there’s always this concern about the beam vibrating or moving,” Ram says.

“With photonic integration, you’re not concerned about beam-pointing stability, because it’s all on the same chip that the electrodes are on. So now everything is registered against each other, and it’s stable.”

The researchers’ new chip is built on a quartz substrate. On top of the quartz is a network of silicon nitride “waveguides,” which route laser light across the chip. Above the waveguides is a layer of glass, and on top of that are the niobium electrodes. Beneath the holes in the electrodes, the waveguides break into a series of sequential ridges, a “diffraction grating” precisely engineered to direct light up through the holes and concentrate it into a beam narrow enough that it will target a single ion, 50 micrometers above the surface of the chip.

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“We believe that surface traps are a key technology to enable these systems to scale to the very large number of ions that will be required for large-scale quantum computing,” says Sage, who co-leads MIT's Lincoln Laboratory’s trapped-ion quantum-information-processing project. “These cage traps work very well, but they really only work for maybe 10 to 20 ions, and they basically max out around there.”

The prototype chip evaluated by the researchers was tested for performance of the diffraction gratings and the ion traps, but there was no mechanism for varying the amount of light delivered to each ion. In ongoing work, the researchers are investigating the addition of light modulators to the diffraction gratings, so that different qubits can simultaneously receive light of different, time-varying intensities.

"We believe that surface traps are a key technology to enable these systems to scale to the very large number of ions that will be required for large-scale quantum computing."

This would make programming the qubits more efficient, which is vital in a practical quantum information system, since the number of quantum operations the system can perform is limited by the “coherence time” of the qubits.

“As far as I know, this is the first serious attempt to integrate optical waveguides in the same chip as an ion trap, which is a very significant step forward on the path to scaling up ion-trap quantum information processors [QIP] to the sort of size which will ultimately contain the number of qubits necessary for doing useful QIP,” says David Lucas, a professor of physics at Oxford University.

“Trapped-ion qubits are well-known for being able to achieve record-breaking coherence times and very precise operations on small numbers of qubits. Arguably, the most important area in which progress needs to be made is technologies which will enable the systems to be scaled up to larger numbers of qubits. This is exactly the need being addressed so impressively by this research.”

“Of course, it's important to appreciate that this is a first demonstration,” Lucas adds. “But there are good prospects for believing that the technology can be improved substantially. As a first step, it's a wonderful piece of work.”

SOURCE  MIT News

By 33rd Square

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 Quantum Computers  

Researchers have developed a micro-fabricated ion trap architecture that holds promise for increasing the density of qubits in future quantum computers.

Quantum computers are in theory capable of simulating the interactions of molecules at a level of detail far beyond the capabilities of even the largest supercomputers today. Such simulations could revolutionize chemistry, biology and material science, but the development of quantum computers has been limited by the ability to increase the number of quantum bits, or qubits, that encode, store and access large amounts of data.

In a paper appearing in the Journal of Applied Physics, a team of researchers at Georgia Tech Research Institute and Honeywell International have demonstrated a new device that allows more electrodes to be placed on a chip—an important step that could help increase qubit densities and bring us one step closer to a quantum computer that can simulate molecules or perform other algorithms of interest.

"To write down the quantum state of a system of just 300 qubits, you would need 2^300 numbers, roughly the number of protons in the known universe, so no amount of Moore's Law scaling will ever make it possible for a classical computer to process that many numbers," said Nicholas Guise, who led the research. "This is why it's impossible to fully simulate even a modest sized quantum system, let alone something like chemistry of complex molecules, unless we can build a quantum computer to do it."

"We all hope that someday quantum computers will fulfill their vast promise, and this research gets us one step closer to that."

The key challenge that quantum computer makers have faced is scaling this technology up, is akin to the progress from the first transistors to the first computers.

One leading qubit candidate is individual ions trapped inside a vacuum chamber and manipulated with lasers. The scalability of current trap architectures is limited since the connections for the electrodes needed to generate the trapping fields come at the edge of the chip, and their number are therefore limited by the chip perimeter.

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The GTRI/Honeywell approach uses new microfabrication techniques that allow more electrodes to fit onto the chip while preserving the laser access needed.

The team's design borrows ideas from a type of packaging called a ball grid array (BGA) that is used to mount integrated circuits. The ball grid array's key feature is that it can bring electrical signals directly from the backside of the mount to the surface, thus increasing the potential density of electrical connections.

"We all hope that someday quantum computers will fulfill their vast promise, and this research gets us one step closer to that," Guise said.

The researchers also freed up more chip space by replacing area-intensive surface or edge capacitors with trench capacitors and strategically moving wire connections.

The space-saving moves allowed tight focusing of an addressing laser beam for fast operations on single qubits. Despite early difficulties bonding the chips, a solution was developed in collaboration with Honeywell, and the device was trapping ions from the very first day.

The team was excited with the results. "Ions are very sensitive to stray electric fields and other noise sources, and a few microns of the wrong material in the wrong place can ruin a trap. But when we ran the BGA trap through a series of benchmarking tests we were pleasantly surprised that it performed at least as well as all our previous traps," Guise said.

The researchers say much work remains to be done to shrink the technology. The BGA project demonstrated that it's possible to fit more and more electrodes on a surface trap chip while wiring them from the back of the chip in a compact and extensible way. However, there are a host of engineering challenges that still need to be addressed to turn this into a miniaturized, robust and nicely packaged system that would enable quantum computing, the researchers say.


SOURCE  American Institute of Physics via NewsWise

By 33rd Square

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Quantum Computers  

The promise of quantum computers has a big obstacle to overcome—the environments of the devices easily introduce error to the system. Now researchers have created a small quantum computing array that for the first time performs with a Sudoku-like error correction method that might pave the way toward practical devices. The team behind the breakthrough have also just joined Google, to further their research.

R
esearchers in the UC Santa Barbara’s physics professor John Martinis’ lab have developed quantum circuitry that self-checks for errors and suppresses them, preserving a qubits’ state(s) and imbuing the system with the highly sought-after reliability that may be the long sought after foundation for the building large-scale superconducting quantum computers.

Keeping qubits error-free, or stable enough to reproduce the same result time and time again, is one of the major hurdles scientists on the forefront of quantum computing face.

“One of the biggest challenges in quantum computing is that qubits are inherently faulty,” said Julian Kelly, graduate student researcher and co-lead author of a research paper that was published in the journal Nature. “So if you store some information in them, they’ll forget it.”

Unlike classical computing, in which the computer bits exist on one of two binary (“yes/no”, or “true/false”) positions, qubits can exist at any and all positions simultaneously, in various dimensions. It is this property, called “superpositioning,” that gives quantum computers their phenomenal computational power, but it is also this characteristic which makes qubits prone to “flipping,” especially when in unstable environments, and thus difficult to work with.

 “It’s hard to process information if it disappears,” said Kelly.

However, that obstacle may just have been cleared by Kelly, postdoctoral researcher Rami Barends, staff scientist Austin Fowler and others in the Martinis Group.

The error process involves creating a scheme in which several qubits work together to preserve the information, said Kelly. To do this, information is stored across several qubits.

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“And the idea is that we build this system of nine qubits, which can then look for errors,” he said. Qubits in the grid are responsible for safeguarding the information contained in their neighbors, he explained, in a repetitive error detection and correction system that can protect the appropriate information and store it longer than any individual qubit can.

“This is the first time a quantum device has been built that is capable of correcting its own errors,” said Fowler. For the kind of complex calculations the researchers envision for an actual quantum computer, something up to a hundred million qubits would be needed, but before that a robust self-check and error prevention system is necessary.

Key to this quantum error detection and correction system is a scheme developed by Fowler, called the surface code. It uses parity information — the measurement of change from the original data (if any) — as opposed to the duplication of the original information that is part of the process of error detection in classical computing. That way, the actual original information that is being preserved in the qubits remains unobserved as follows quantum physics.

"This is the first time a quantum device has been built that is capable of correcting its own errors."

“You can’t measure a quantum state, and expect it to still be quantum,” explained Barends. The very act of measurement locks the qubit into a single state and it then loses its superpositioning power, he said. Therefore, in something akin to a Sudoku puzzle, the parity values of data qubits in a qubit array are taken by adjacent measurement qubits, which essentially assess the information in the data qubits by measuring around them.

“So you pull out just enough information to detect errors, but not enough to peek under the hood and destroy the quantum-ness,” said Kelly.

This development represents a meeting of the best in the science behind the physical and the theoretical in quantum computing — the latest in qubit stabilization and advances in the algorithms behind the logic of quantum computing.

“It’s a major milestone,” said Barends. “Because it means that the ideas people have had for decades are actually doable in a real system.”

The Martinis Group continues to refine its research to develop this important new tool. This particular quantum error correction has been proved to protect against the “bit-flip” error, however the researchers have their eye on correcting the complimentary error called a “phase-flip,” as well as running the error correction cycles for longer periods to see what behaviors might emerge.

Martinis and the senior members of his research group have, since this research was performed, entered into a partnership with Google.

The recruitment of the Martinis group signals Google's intent to recruit or tap into talent with wide-ranging expertise at the Google Quantum Artificial Intelligence Lab which also involves NASA. The move also inaugurates a new era of cooperation between academic researchers and D-Wave (under the Google umbrella). The scenario would have seemed unbelievable just several years ago because of the skepticism and heated debates surrounding D-Wave's machines.

SOURCE  UCSB

By 33rd Square

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