Australian
researchers confirm the promise of silicon for quantum computing.
Australian researchers have measured the fidelity of
two-qubit logic operations in silicon for the first time ever, with highly
promising results that will allow a full-scale quantum processor to be scaled.
The research, conducted by the UNSW Engineering team of
Professor Andrew Dzurak, has been published in the world-renowned journalNature today. The true accuracy of such a two-qubit gate was unknown until this
landmark paper today.
Australian researchers confirm the promise of silicon for quantum computing.
Dzurak's team was the first to construct a quantum logic
gate in silicon in 2015, enabling calculations between two qubits of
information – and thus clearing up a crucial hurdle to make silicon quantum
computers a reality.
Important accuracy for success
of quantum computing
In this study, the team applied and conducted Clifford-based
fidelity benchmarking-a technique that can assess qubit accuracy across all
technology platforms-showing an average fidelity of 98 percent to two-qubit
gates.
“Most of important Quantum applications, millions of qubits
will be needed, and you're going to have to correct quantum errors, even when
they’re small,” Professor Dzurak says.
“The more accurate your qubits, the fewer you need – and
therefore, the sooner we can ramp up the engineering and manufacturing to
realise a full-scale quantum computer.”
Concrete
path to silicon in quantum computing
“If our fidelity value had been too low, it would have meant
serious problems for the future of silicon quantum computing. The fact that it
is near 99% puts it in the ballpark we need, and there are excellent prospects
for further improvement. Our results immediately show, as we predicted, that
silicon is a viable platform for full-scale quantum computing,” Professor
Dzurak says.
Recently published in Nature Electronics and featured on its
cover – where Dr. Yang is the lead author, the same team also recorded the
world's most accurate 1-qubit gate in a silicon quantum dot with a remarkable
99.96 percent fidelity.
“Besides the natural advantages of silicon qubits, one key
reason we’ve been able to achieve such impressive results is because of the
fantastic team we have here at UNSW. My student Wister and Dr Yang are both
incredibly talented. They personally conceived the complex protocols required
for this benchmarking experiment,” says Professor Dzurak.
UNSW Dean of Engineering, Professor Mark Hoffman, says “Quantum
computing is this century’s space race – and Sydney is leading the charge.”
“This milestone is another step towards realising a
large-scale quantum computer – and it reinforces the fact that silicon is an
extremely attractive approach that we believe will get UNSW there first.”
“Our latest result brings us closer to commercialising this
technology – my group is all about building a quantum chip that can be used for
real-world applications,” Professor Dzurak says.
The silicon qubit device used in this study was manufactured
entirely at UNSW using a unique silicon-CMOS process line, high-resolution
patterning systems, and supporting equipment made available by ANFF-NSW for
nanofabrication.
Australian Researchers Unveil First Complete Silicon Quantum Computer Processor
UNSW
16 DEC 2017
A reimagining of today’s computer chips by UNSW engineers shows how a quantum computer can be manufactured – using mostly standard silicon technology.
A reimagining of today’s computer chips by Australian and Dutch engineers shows how a quantum computer can be manufactured – using mostly standard silicon technology.
Australian Researchers Unveil First Complete Silicon Quantum Computer Processor
Research teams all over the world are exploring different ways to design a working computing chip that can integrate quantum interactions. Now, UNSW engineers believe they have cracked the problem, reimagining the silicon microprocessors we know to create a complete design for a quantum computer chip that can be manufactured using mostly standard industry processes and components.
The new chip design, published in the journal Nature Communications, details a novel architecture that allows quantum calculations to be performed using existing semiconductor components, known as CMOS (complementary metal-oxide-semiconductor) – the basis for all modern chips.
It was devised by Andrew Dzurak, director of the Australian National Fabrication Facility at the University of New South Wales (UNSW), and Menno Veldhorst, lead author of the paper who was a research fellow at UNSW when the conceptual work was done.
“We often think of landing on the Moon as humanity’s greatest technological marvel,” said Dzurak, who is also a Program Leader at Australia’s famed Centre of Excellence for Quantum Computation and Communication Technology (CQC2T). “But creating a microprocessor chip with a billion operating devices integrated together to work like a symphony – that you can carry in your pocket! – is an astounding technical achievement, and one that’s revolutionised modern life.
“With quantum computing, we are on the verge of another technological leap that could be as deep and transformative. But a complete engineering design to realise this on a single chip has been elusive. I think what we have developed at UNSW now makes that possible. And most importantly, it can be made in a modern semiconductor manufacturing plant,” he added.
Veldhorst, now a team leader in quantum technology at QuTech – a collaboration between Delft University of Technology and TNO, the Netherlands Organisation for Applied Scientific Research – said the power of the new design is that, for the first time, it charts a conceivable engineering pathway toward creating millions of quantum bits, or qubits.
“Remarkable as they are, today’s computer chips cannot harness the quantum effects needed to solve the really important problems that quantum computers will. To solve problems that address major global challenges – like climate change or complex diseases like cancer – it’s generally accepted we will need millions of qubits working in tandem. To do that, we will need to pack qubits together and integrate them, like we do with modern microprocessor chips. That’s what this new design aims to achieve.
“Our design incorporates conventional silicon transistor switches to ‘turn on’ operations between qubits in a vast two-dimensional array, using a grid-based ‘word’ and ‘bit’ select protocol similar to that used to select bits in a conventional computer memory chip,” he added. “By selecting electrodes above a qubit, we can control a qubit’s spin, which stores the quantum binary code of a 0 or 1. And by selecting electrodes between the qubits, two-qubit logic interactions, or calculations, can be performed between qubits.”
A quantum computer exponentially expands the vocabulary of binary code used in modern computers by using two spooky principles of quantum physics – namely, ‘entanglement’ and ‘superposition’. Qubits can store a 0, a 1, or an arbitrary combination of 0 and 1 at the same time. And just as a quantum computer can store multiple values at once, so it can process them simultaneously, doing multiple operations at once.
This would allow a universal quantum computer to be millions of times faster than any conventional computer when solving a range of important problems.
There are at least five major quantum computing approaches being explored worldwide: silicon spin qubits, ion traps, superconducting loops, diamond vacancies and topological qubits; UNSW’s design is based on silicon spin qubits. The main problem with all of these approaches is that there is no clear pathway to scaling the number of quantum bits up to the millions needed without the computer becoming huge a system requiring bulky supporting equipment and costly infrastructure.
That’s why UNSW’s new design is so exciting: relying on its silicon spin qubit approach – which already mimics much of the solid-state devices in silicon that are the heart of the US$380 billion global semiconductor industry – it shows how to dovetail spin qubit error correcting code into existing chip designs, enabling true universal quantum computation.
Unlike almost every other major group elsewhere, CQC2T’s quantum computing effort is obsessively focused on creating solid-state devices in silicon, from which all of the world’s computer chips are made. And they’re not just creating ornate designs to show off how many qubits can be packed together, but aiming to build qubits that could one day be easily fabricated – and scaled up.
“It’s kind of swept under the carpet a bit, but for large-scale quantum computing, we are going to need millions of qubits,” said Dzurak. “Here, we show a way that spin qubits can be scaled up massively. And that’s the key.”
The design is a leap forward in silicon spin qubits; it was only two years ago, in a paper in Nature, that Dzurak and Veldhorst showed, for the first time, how quantum logic calculations could be done in a real silicon device, with the creation of a two-qubit logic gate – the central building block of a quantum computer.
“Those were the first baby steps, the first demonstrations of how to turn this radical quantum computing concept into a practical device using components that underpin all modern computing,” said Mark Hoffman, UNSW’s Dean of Engineering. “Our team now has a blueprint for scaling that up dramatically.
“We’ve been testing elements of this design in the lab, with very positive results. We just need to keep building on that – which is still a hell of a challenge, but the groundwork is there, and it’s very encouraging. It will still take great engineering to bring quantum computing to commercial reality, but clearly the work we see from this extraordinary team at CQC2T puts Australia in the driver’s seat,” he added.
Other CQC2T researchers involved in the design published in the Nature Communications paper were Henry Yang and Gertjan Eenink, the latter of whom has since joined Veldhorst at QuTech.
The UNSW team has struck a A$83 million deal between UNSW, Telstra, Commonwealth Bank and the Australian and New South Wales governments to develop, by 2022, a 10-qubit prototype silicon quantum integrated circuit – the first step in building the world’s first quantum computer in silicon.
In August, the partners launched Silicon Quantum Computing Pty Ltd, Australia’s first quantum computing company, to advance the development and commercialisation of the team’s unique technologies. The NSW Government pledged A$8.7 million, UNSW A$25 million, the Commonwealth Bank A$14 million, Telstra A$10 million and the Australian Government A$25 million.
STILLS: Pictures of Dzurak and Veldhorst, plus illustrations of the complete quantum computer chip. (Photos: Grant Turner/UNSW, Illustrations: Tony Melov/UNSW)
BACKGROUNDERS: How UNSW’s ‘silicon spin qubit’ design compares with other approaches; plus a free 3,000-word feature article on the UNSW effort (Creative Commons).
SCIENTIFIC PAPER: Original paper in Nature Communications, “Silicon CMOS architecture for a spin-based quantum computer”.
Key component to scale up quantum computing invented
28 November 2017
Sydney team develops microcircuit based on Nobel Prize research
Invention of the mrowave circulator is part of a revolution in device engineering needed to build a large-scale quantum computer.
A team at the University of Sydney and Microsoft, in collaboration with Stanford University in the US, has miniaturised a component that is essential for the scale-up of quantum computing. The work constitutes the first practical application of a new phase of matter, first discovered in 2006, the so-called topological insulators.
[caption id="attachment_840" align="aligncenter" width="1280"] University of Sydney Miniaturised a Component for the Scale-up of Quantum Computing[/caption]
Beyond the familiar phases of matter - solid, liquid, or gas - topological insulators are materials that operate as insulators in the bulk of their structures but have surfaces that act as conductors. Manipulation of these materials provide a pathway to construct the circuitry needed for the interaction between quantum and classical systems, vital for building a practical quantum computer.
The Sydney team’s component, coined a microwave circulator, acts like a traffic roundabout, ensuring that electrical signals only propagate in one direction, clockwise or anti-clockwise, as required. Similar devices are found in mobile phone base-stations and radar systems, and will be required in large quantities in the construction of quantum computers. A major limitation, until now, is that typical circulators are bulky objects the size of your hand.
This invention, reported by the Sydney team today in the journal Nature Communications, represents the miniaturisation of the common circulator device by a factor of 1000. This has been done by exploiting the properties of topological insulators to slow the speed of light in the material. This minaturisation paves the way for many circulators to be integrated on a chip and manufactured in the large quantities that will be needed to build quantum computers.
Microsoft teams up with Sydney University for Quantum Computing
The University of Sydney
25/07/2017
Australian lab part of IT giant's ramped-up quantum computing bid Share
A multi-year partnership announced today establishes ongoing investment focused on Sydney’s Quantum Nanoscience Laboratory to scale-up devices, as Microsoft moves from research to real-world engineering of quantum machines.
The University of Sydney today announces the signing of a multi-year quantum computing partnership with Microsoft, creating an unrivalled setting and foundation for quantum research in Sydney and Australia.
[caption id="attachment_835" align="aligncenter" width="704"] Microsoft teams up with Sydney University for Quantum Computing[/caption]
The long-term Microsoft investment will bring state of the art equipment, allow the recruitment of new staff, help build the nation’s scientific and engineering talent, and focus significant research project funding into the University, assuring the nation a key role in the emerging “quantum economy.”
David Pritchard, Chief of Staff for Microsoft’s Artificial Intelligence and Research Group and Douglas Carmean, Partner Architect of Microsoft’s Quantum Architectures and Computation (QuArC) group, participated in the announcement at the University of Sydney’s Nanoscience Hub.
The official establishment of Station Q Sydney today embeds Microsoft’s commitment to kickstarting the emergence of a quantum economy by partnering with the University to develop a premier centre for quantum computing.
Directed by Professor David Reilly from the School of Physics and housed inside the $150 million Sydney Nanoscience Hub, Station Q Sydney joins Microsoft’s other experimental research sites at Purdue University, Delft University of Technology, and the University of Copenhagen. There are only four labs of this kind in the world.
We’ve reached a point where we can move from theory to applied engineering for significant scale-up.
Professor David Reilly
Sydney-born Professor Reilly – who completed a postdoctoral fellowship at Harvard University before returning to Australia – asserts that quantum computing is one of the most significant opportunities in the 21st century, with the potential to transform the global economy and society at large.
“The deep partnership between Microsoft and the University of Sydney will allow us to help build a rich and robust local quantum economy by attracting more skilled people, investing in new equipment and research, and accelerate progress in quantum computing – a technology that we believe will disrupt the way we live, reshaping national and global security and revolutionising medicine, communications and transport,” Professor Reilly said.
The focus of Professor Reilly and his team at Station Q Sydney is to bring quantum computing out of the laboratory and into the real world where it can have genuine impact: “We’ve reached a point where we can move from mathematical modelling and theory to applied engineering for significant scale-up,” Professor Reilly said.
Leveraging his research in quantum computing, Professor Reilly’s team has already demonstrated how spin-off quantum technologies can be used in the near-future to help detect and track early-stage cancers using the quantum properties of nanodiamonds. Watch the video animation.
Microsoft’s David Pritchard outlined the company’s redoubled quantum efforts, a key strategic pillar within Microsoft’s AI and Research Group; the quantum computing effort is being led by Todd Holmdahl, the creator of the Xbox and HoloLens.
Mr Pritchard said the partnership with the University of Sydney was important because Microsoft is looking forward to reaching the critical juncture where theory and demonstration need to segue and be complemented by systems-level abstraction and applied engineering efforts focused on scaling.
“There’s always an element of risk when you are working on projects with the potential to make momentous and unprecedented impact; we’re at the inflection point now where we have the opportunity to do that,” Mr Pritchard said.
D-Wave Systems Announces the General Availability of the 1000+ Qubit D-Wave 2X Quantum Computer
New system has twice the qubits of the D-Wave Two and new benchmarks demonstrate increasing performance advantage over specialized highly tuned algorithms on classical systems
Palo Alto, CA August 20, 2015
D-Wave Systems Inc., the world's first quantum computing company, today announced the general availability of the D-Wave 2X™ quantum computing system. The D-Wave 2X features a 1000+ qubit quantum processor and numerous design improvements that result in larger problem sizes, faster performance and higher precision. At 1000+ qubits, the D-Wave 2X quantum processor evaluates all 21000 possible solutions simultaneously as it converges on optimal or near optimal solutions, more possibilities than there are particles in the observable universe. No conventional computer of any kind could represent this many possibilities simultaneously, further illustrating the powerful nature of quantum computation.
[caption id="attachment_625" align="aligncenter" width="480"] The General Availability of the 1000+ Qubit D-Wave 2X Quantum Computer[/caption]
The D-Wave 2X demonstrates a factor of up to 15x gains over highly specialized classical solvers in nearly all classes of problems examined. Measuring only the native computation time of the D-Wave 2X quantum processor shows performance advantages of up to 600x over these same solvers.
Jeremy Hilton, vice president of processor development at D-Wave, said, “The D-Wave 2X marks the latest step forward in our aggressive performance trajectory. Our first system, the D-Wave One™ system, was the first scalable quantum computer, but was slower than general-purpose optimization software. The next generation D-Wave Two™ system significantly outperformed the general-purpose optimization software, but was only comparable to specialized highly tuned heuristic algorithms. With the D-Wave 2X system we have surpassed the performance of these specialized algorithms, providing incentive for users to develop methods to harness this revolutionary technology for their own applications.”
To showcase the performance of the new system, a paper outlining benchmark results for a set of problems native to the D-Wave 2X system will be posted to the arXiv. A summary of the results and a link to the paper are on the company’s blog.
The benchmark includes a set of synthetic discrete combinatorial optimization problems intended to be representative of real world challenges. Some application challenges currently under study at D-Wave involve algorithms that tune stock portfolios or underlie machine learning used in bioinformatics, inductive logic programming, and natural language processing and computer vision.
“D-Wave continues to advance the state-of-the-art of quantum computing at a rapid pace, with a number of impressive application results, and the release of their 1000 qubit D-Wave 2X system is another major milestone in the industry,” said Earl Joseph, IDC program vice president for HPC. “Complementing today’s high performance computing systems, quantum computers will likely become an important tool to solve important problems that can’t be solved today.”
In addition to scaling beyond 1000 qubits, the new system incorporates other major technological and scientific advancements. These include an operating temperature below 15 millikelvin, near absolute zero and 180 times colder than interstellar space. With over 128,000 Josephson tunnel junctions, the new processors are believed to be the most complex superconductor integrated circuits ever successfully used in production systems. Increased control circuitry precision and a 50% reduction in noise also contribute to faster performance and enhanced reliability.
The D-Wave 2X system is available immediately for shipment and installation.
About D-Wave Systems Inc. D-Wave Systems is the first quantum computing company. Its mission is to integrate new discoveries in physics, engineering, manufacturing, and computer science into breakthrough approaches to computation to help solve some of the world’s most complex challenges. The company's quantum computers are built using a novel type of superconducting processor that uses quantum mechanics to massively accelerate computation. D-Wave’s customers include some of the world’s most prominent organizations including Lockheed Martin, Google and NASA. With headquarters near Vancouver, Canada, D-Wave U.S. is based in Palo Alto, California. D-Wave has a blue-chip investor base including Bezos Expeditions, BDC Capital, DFJ, Goldman Sachs, Growthworks, Harris & Harris Group, In-Q-Tel, International Investment and Underwriting, and Kensington Partners Limited. For more information, visit: www.dwavesys.com.
Graphene layer reads optical information from nanodiamonds electronically
Nitrogen-vacancy centers in diamonds could be used to construct vital components for quantum computers. But hitherto it has been impossible to read optically written information from such systems electronically. Using a graphene layer, a team of scientists headed by Professor Alexander Holleitner of the Technische Universität München (TUM) has now implemented just such a read unit.
[caption id="attachment_498" align="aligncenter" width="650"]This image shows a laboratory set-up measuring the interaction between graphene and nano-diamonds with implanted nitrogen-vacancy centers.[/caption]
Ideally, diamonds consist of pure carbon. But natural diamonds always contain defects. The most researched defects are nitrogen-vacancy centers comprising a nitrogen atom and a vacancy. These might serve as highly sensitive sensors or as register components for quantum computers. However, until now it has not been possible to extract the optically stored information electronically.
A team headed by Professor Alexander Holleitner, physicist at the TU München and Frank Koppens, physics professor at the Institut de Ciencies Fotoniques near Barcelona, have now devised just such a methodology for reading the stored information. The technique builds on a direct transfer of energy from nitrogen-vacancy centers in nanodiamonds to a directly neighboring graphene layer.
Non-radiative energy transfer
When laser light shines on a nanodiamond, a light photon raises an electron from its ground state to an excited state in the nitrogen-vacancy center. "The system of the excited electron and the vacated ground state can be viewed as a dipole," says Professor Alexander Holleitner. "This dipole, in turn, induces another dipole comprising an electron and a vacancy in the neighboring graphene layer."
In contrast to the approximately 100 nanometer large diamonds, in which individual nitrogen-vacancy centers are insulated from each other, the graphene layer is electrically conducting. Two gold electrodes detect the induced charge, making it electronically measureable.
Picosecond electronic detection
Essential for this experimental setup is that the measurement is made extremely quickly, because the generated electron-vacancy pairs disappear after only a few billionths of a second. However, the technology developed in Holleitners laboratory allows measurements in the picosecond domain (trillionths of a second). The scientists can thus observe these processes very closely.
"In principle our technology should also work with dye molecules," says doctoral candidate Andreas Brenneis, who carried out the measurements in collaboration with Louis Gaudreau. "A diamond has some 500 point defects, but the methodology is so sensitive that we should be able to even measure individual dye molecules."
As a result of the extremely fast switching speeds of the nanocircuits developed by the researchers, sensors built using this technology could be used not only to measure extremely fast processes. Integrated into future quantum computers they would allow clock speeds ranging into the terahertz domain.
Elusive quantum transformations found near absolute zero
Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition
UPTON, NY—Heat drives classical phase transitions—think solid, liquid, and gas—but much stranger things can happen when the temperature drops. If phase transitions occur at the coldest temperatures imaginable, where quantum mechanics reigns, subtle fluctuations can dramatically transform a material.
[caption id="attachment_424" align="aligncenter" width="400"]Quantum Transformations Found Near Absolute Zero[/caption]
Scientists from the U.S. Department of Energy's Brookhaven National Laboratory and Stony Brook University have explored this frigid landscape of absolute zero to isolate and probe these quantum phase transitions with unprecedented precision.
"Under these cold conditions, the electronic, magnetic, and thermodynamic performance of metallic materials is defined by these elusive quantum fluctuations," said study coauthor Meigan Aronson, a physicist at Brookhaven Lab and professor at Stony Brook. "For the first time, we have a picture of one of the most fundamental electron states without ambient heat obscuring or complicating those properties."
The scientists explored the onset of ferromagnetism—the same magnetic polarization exploited in advanced electronic devices, electrical motors, and even refrigerator magnets—in a custom-synthesized iron compound as it approached absolute zero.
The research provides new methods to identify and understand novel materials with powerful and unexpected properties, including superconductivity—the ability to conduct electricity with perfect efficiency. The study will be published online Sept. 15, 2014, in the journal Proceedings of the National Academy of Sciences.
"Exposing this quantum phase transition allows us to predict and potentially boost the performance of new materials in practical ways that were previously only theoretical," said study coauthor and Brookhaven Lab physicist Alexei Tsvelik.
Mapping Quantum Landscapes
The presence of heat complicates or overpowers the so-called quantum critical fluctuations, so the scientists conducted experiments at the lowest possible temperatures.
"The laws of thermodynamics make absolute zero unreachable, but the quantum phase transitions can actually be observed at nonzero temperatures," Aronson said. "Even so, in order to deduce the full quantum mechanical nature, we needed to reach temperatures as low as 0.06 Kelvin—much, much colder than liquid helium or even interstellar space."
The researchers used a novel compound of yttrium, iron, and aluminum (YFe2Al10), which they discovered while searching for new superconductors. This layered, metallic material sits poised on the threshold of ferromagnetic order, a key and very rare property.
"Our thermodynamic and magnetic measurements proved that YFe2Al10 becomes ferromagnetic exactly at absolute zero—a sharp contrast to iron, which is ferromagnetic well above room temperature," Aronson said. "Further, we used magnetic fields to reverse this ferromagnetic order, proving that quantum fluctuations were responsible."
The collaboration produced near-perfect samples to prove that material defects could not impact the results. They were also the first group to prepare YFe2Al10 in single-crystal form, which allowed them to show that the emergent magnetism resided within two-dimensional layers.
"As the ferromagnetism decayed with heat or applied magnetic fields, we used theory to identify the spatial and temporal fluctuations that drove the transition," Tsvelik said. "That fundamental information provides insight into countless other materials."
Quantum Clues to New Materials
The scientists plan to modify the composition of YFe2Al10 so that it becomes ferromagnetic at nonzero temperatures, opening another window onto the relationship between temperature, quantum transitions, and material performance.
"Robust magnetic ordering generally blocks superconductivity, but suppressing this state might achieve the exact balance of quantum fluctuations needed to realize unconventional superconductivity," Tsvelik said. "It is a matter of great experimental and theoretical interest to isolate these competing quantum interactions that favor magnetism in one case and superconductivity on the other."
Added Aronson, "Having more examples displaying this zero-temperature interplay of superconductivity and magnetism is crucial as we develop a holistic understanding of how these phenomena are related and how we might ultimately control these properties in new generations of materials."
###
Other authors on this study include Liusuo Wu, Moosung Kim, and Keeseong Park, all of Stony Brook University's Department of Physics and Astronomy.
The research was conducted at Brookhaven Lab's Condensed Matter Physics and Materials Science Department and supported by the U.S. Department of Energy's Office of Science (BES).
Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.
NIST ion duet offers tunable module for quantum simulator
BOULDER, Colo -- Physicists at the National Institute of Standards and Technology (NIST) have demonstrated a pas de deux of atomic ions that combines the fine choreography of dance with precise individual control.
NIST Ion Duet Could be Used to Perform Logic Operations in Quantum Computers
NIST's ion duet, described in the August 7 issue of Nature, is a component for a flexible quantum simulator that could be scaled up in size and configured to model quantum systems of a complexity that overwhelms traditional computer simulations. Beyond simulation, the duet might also be used to perform logic operations in future quantum computers, or as a quantum-enhanced precision measurement tool.
In the experiments, researchers coaxed two beryllium ions located in separate zones of an electric-field trap (a storage device) into an "entangled" state. An important resource for quantum technologies, entanglement involves an intimate connection between the particles such that a measurement of one ordains the state of the other. This is the first time ions in separate zones have been entangled by manipulating their electric interactions, an important feature that could be used in quantum simulation and computing.
The work demonstrates a high level of quantum control with microfabricated trap technology well suited to the scaling-up needed to make powerful quantum information processors. Having separate trapping zones enabled the research team to tune the ions' interactions from weak to strong—a feature expected to be useful for simulating the behavior of complex quantum materials.
"Even though the ions are confined apart from one another, we can now entangle them," NIST physicist Andrew Wilson says. "We plan to use this for quantum simulation and computing, but when I explain to my family what we're doing, the remote entanglement sounds kind of romantic."
"We focus on the idea that everything needs to be scalable," Wilson notes. "To do useful simulations we'll need versatile traps with more than two ions, and making traps using the same technology used to make computer chips gives us this capability. NIST pioneered this approach and we're fortunate to have great facilities for doing this sort of work."
Inducing the ions to perform a number of intricate quantum dances, the researchers first coaxed the ions to exchange a single quantum of vibrational energy (the smallest amount that nature allows). They then used lasers and microwaves to entangle the ions' "spins." Analogous to tiny bar magnets, the spins of the entangled ions pointed in the same direction, but were also in a "superposition" of pointing in the opposite direction at the same time. Superposition is another strange but useful feature of the quantum world.
The researchers say that extending the new module to make a two-dimensional network of a few tens of ions would be enough to perform useful simulations of phenomena that are extremely difficult to model even on the most powerful traditional computers. An example is the high-temperature superconductitivity—electron flow without resistance—observed in certain ceramics. Despite more than 20 years of study, the underlying mechanism remains a mystery. A quantum simulator might provide deeper insights.
The ion duet also could be used to perform logic operations in quantum computers, which would have a wider range of applications than quantum simulators. And NIST researchers also envision the ion duet as a sensor, in which one well-controlled ion is used to investigate a second ion with interesting features. For instance, a beryllium ion might be used to probe a charged anti-matter particle in another trap zone, Wilson says.
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This research was funded by the Office of the Director of National Intelligence, the Intelligence Advanced Research Projects Activity and the Office of Naval Research. A.C. Wilson, Y. Colombe, K.R. Brown, E. Knill, D. Leibfried and D.J. Wineland. Entangling spin-spin interactions of ions in individually controlled potential wells. Nature. August 7. DOI 10.1038/nature13565.
Physicists find way to boot up quantum computers 72 times faster than previously possible
Press the start button, switch on the monitor, grab a cup of coffee and off you go. That is pretty much how most us experience booting up a computer. But with a quantum computer the situation is very different. So far, researchers have had to spend hours making dozens of adjustments and fine calibrations in order to set up a chip with just five quantum bits so that it can be used for experimental work. (One quantum bit or 'qubit' is the quantum physical equivalent of a single bit in a conventional computer). Any small errors in the adjustment and calibration procedure and the chip would not work.
Way to Boot up Quantum Computers 72 Times Faster Than Previously Possible
The problem is that, not unlike musical instruments, quantum computers react to small changes in the local environment. If, for example, it is a little warmer or a little colder or if the ambient air pressure is a little higher or a little lower than the day before then the complex network of qubits will no longer function – the computer is detuned and has to be readjusted before it can be used. 'Up until now, experimental quantum physicists have had to sit down each day and see how conditions have changed compared to the day before. They then had to remeasure each parameter and carefully recalibrate the chip,' explains Professor Wilhelm-Mauch, Professor for Theoretical Quantum and Solid-State Physics at Saarland University. Only a very small error rate of less than 0.1 percent is permissible when measuring ambient conditions. Frank Wilhelm-Mauch explains this sensitivity thus: 'That means that an error can occur in only one in a thousand measurements. If just two in a thousand measurements are in error, the software will be unable to correct for the errors and the quantum computer will not operate correctly.' With around 50 different parameters involved in the calibration process, one begins to get an idea of the sheer effort involved in calibrating a quantum computer.
Working together with his doctoral student, Wilhelm-Mauch began to consider a fundamentally new approach to the problem. 'We asked ourselves the question: Why is it necessary each and every day to understand how conditions differ from those of the day before?' The answer we eventually came up with was that it isn't necessary. What's important is that the setup procedure produces the right results. Why it produces the right results is not so relevant.' It was this pragmatic approach that underlay the work carried out by Wilhelm-Mauch and Egger. 'For the calibration procedure we used an algorithm from engineering mathematics, strictly speaking from the field of civil and structural engineering, as that's another area in which experiments are costly,' explains Professor Wilhelm-Mauch.
Using this technique, the two theoreticians were able to reduce the calibration error rate to below the required 0.1 percent threshold, while at the same time speeding up the calibration process from six hours to five minutes. The Saarbrücken methodology, which goes under the name Ad-HOC (Adaptive Hybrid Optimal Control), has now been subjected to rigorous testing by a group of experimental physicists from the University of California in Santa Barbara. Their experimental work is published in the issue of Physical Review Letters that also contains the Saarbrücken paper.
This development is of major importance for future experimental research into quantum computing. Physicists in quantum computing laboratories no longer have to spend hours every day preparing their system for just a short period of experimental work. 'As many of the parameters, such as temperature, light and air pressure do not remain stable during the long calibration phase, this can further shorten the time window in which the chip is running error-free and in which it can therefore be used for experiments,' says Wilhelm-Mauch, adding that the new method is scalable. Up until now, technical constraints have meant that experiments have been carried out using a single chip housing five qubits that perform the actual computational operations. The new method, in contrast, is not restricted to chips of this magnitude and can be applied to quantum processors of almost any size.
Frank Wilhelm-Mauch jokingly points out another appealing feature of the new methodology: 'Unlike the previous approach of manual calibration, our method is fully automated. The researcher really does just push a button like on a conventional computer. They can then go off to get themselves a coffee while the quantum computer boots up.' A major improvement in the life of experimental research scientists working in the field.
Even computers are error-prone. The slightest disturbances may alter saved information and falsify the results of calculations. To overcome these problems, computers use specific routines to continuously detect and correct errors. This also holds true for a future quantum computer, which will require procedures for error correction as well: "Quantum phenomena are extremely fragile and error-prone. Errors can spread rapidly and severely disturb the computer," says Thomas Monz, member of Rainer Blatt's research group at the Institute for Experimental Physics at the University of Innsbruck. Together with Markus Müller and Miguel Angel Martin-Delgado from the Department for Theoretical Physics at the Complutense University in Madrid, the physicists in Innsbruck developed a new quantum error-correcting method and tested it experimentally. "A quantum bit is extremely complex and cannot be simply copied. Moreover, errors in the microscopic quantum world are more manifold and harder to correct than in conventional computers," underlines Monz. "To detect and correct general errors in a quantum computer, we need highly sophisticated so-called quantum error-correcting codes." The topological code used for this current experiment was proposed by Martin-Delgado's research group in Madrid. It arranges the qubits on a two-dimensional lattice, where they can interact with the neighboring particles.
Quantum computation -Fragile yet error free
A quantum bit encoded in seven ions
For the experiment at the University of Innsbruck the physicists confined seven calcium atoms in an ion trap, which allows them to cool these atoms to almost absolute zero temperature and precisely control them by laser beams. The researchers encoded the fragile quantum states of one logical qubit in entangled states of these particles. The quantum error-correcting code provided the program for this process. "Encoding the logical qubit in the seven physical qubits was a real experimental challenge," relates Daniel Nigg, a member of Rainer Blatt's research group. The physicists achieved this in three steps, where in each step complex sequences of laser pulses were used to create entanglement between four neighboring qubits. "For the first time we have been able to encode a single quantum bit by distributing its information over seven atoms in a controlled way," says an excited Markus Müller, who in 2011 moved from Innsbruck to the Complutense University in Madrid. "When we entangle atoms in this specific way, they provide enough information for subsequent error correction and possible computations."
Error-free operations
In another step the physicists tested the code's capability to detect and correct different types of errors. "We have demonstrated that in this type of quantum system we are able to independently detect and correct every possible error for each particle," says Daniel Nigg. "To do this we only need information about the correlations between the particles and don't have to perform measurements of the single particles," explains Daniel Nigg's colleague Esteban Martinez. In addition to reliably detecting single errors, the physicists were for the first time able to apply single or even repetitive operations on a logical encoded qubit. Once the obstacle of the complex encoding process is overcome, only simple single-qubit gate operations are necessary for each gate operation. "With this quantum code we can implement basic quantum operations and simultaneously correct all possible errors," explains Thomas Monz this crucial milestone on the route towards a reliable and fault tolerant quantum computer.
Basis for future innovations
This new approach developed by the Spanish and Austrian physicists constitutes a promising basis for future innovations. "This 7-ion system applied for encoding one logical quantum bit can be used as a building block for much larger quantum systems," says theoretical physicist Müller. "The bigger the lattice, the more robust it becomes. The result might be a quantum computer that could perform any number of operations without being impeded by errors." The current experiment not only opens new routes for technological innovations: "Here, completely new questions come up, for example which methods can be used in the first place to characterise such large logical quantum bits," says Rainer Blatt with a view into the future. "Moreover, we would also like to collaboratively develop the used quantum codes further to optimize them for even more extensive operations," adds Martin-Delgado.
The researchers are financially supported by the Spanish Ministry of Science, the Austrian Science Fund, the U.S. Government, the European Commission and the Federation of Austrian Industries Tyrol.
An international research group led by the University of Bristol has made an important advance towards a quantum computer by shrinking down key components and integrating them onto a silicon microchip.
Integration brings quantum computer a step closer
Scientists and engineers from an international collaboration led by Dr Mark Thompson from the University of Bristol have, for the first time, generated and manipulated single particles of light (photons) on a silicon chip – a major step forward in the race to build a quantum computer.
Quantum computers and quantum technologies in general are widely anticipated as the next major technology advancement, and are poised to replace conventional information and computing devices in applications ranging from ultra-secure communications and high-precision sensing to immensely powerful computers. While many of the components for a quantum computer already exist, for a quantum computer to be realised, these components need to be integrated onto a single chip.
Featuring today on the front cover of Nature Photonics, this latest advancement is one of the important pieces in the jigsaw needed in order to realise a quantum computer. While previous attempts have required external light sources to generate the photons, this new chip integrates components that can generate photons inside the chip. "We were surprised by how well the integrated sources performed together," admits Joshua Silverstone, lead author of the paper. "They produced high-quality identical photons in a reproducible way, confirming that we could one day manufacture a silicon chip with hundreds of similar sources on it, all working together. This could eventually lead to an optical quantum computer capable of perform enormously complex calculations."
"Single-photon detectors, sources and circuits have all been developed separately in silicon but putting them all together and integrating them on a chip is a huge challenge," explains group leader Mark Thompson. "Our device is the most functionally complex photonic quantum circuit to date, and was fabricated by Toshiba using exactly the same manufacturing techniques used to make conventional electronic devices."
The group, which, includes researchers from Toshiba Corporation (Japan), Stanford University (US), University of Glasgow (UK) and TU Delft (The Netherlands), now plans to integrate the remaining necessary components onto a chip, and show that large-scale quantum devices using photons are possible.
"Our group has been making steady progress towards a functioning quantum computer over the last five years," said Thompson. "We hope to have a photon-based device which can rival modern computing hardware for highly-specialised tasks within the next couple of years."
Much of the work towards this goal will be carried out at Bristol's new Centre for Doctoral Training in Quantum Engineering, which will train a new generation of engineers, scientists and entrepreneurs to harness the power of quantum mechanics using state-of-the-art engineering technique to make real world and useful quantum enhanced devices. This innovative centre bridges the gaps between physics, engineering, mathematics and computer science, working closely with chemists and biologists while interacting strongly with industry.
Overcoming a Key Barrier Towards Building Ultrafast Quantum Computers
15 November 2013
A normally fragile quantum state has been shown to survive at room temperature for a world record 39 minutes, overcoming a key barrier towards building ultrafast quantum computers.
Overcoming a Key Barrier Towards Building Ultrafast Quantum Computers
An international team including Stephanie Simmons of Oxford University, UK, report in this week’s Science a test performed by Mike Thewalt of Simon Fraser University, Canada, and colleagues. In conventional computers data is stored as a string of 1s and 0s. In the experiment quantum bits of information, ‘qubits’, were put into a ‘superposition’ state in which they can be both 1s and 0 at the same time – enabling them to perform multiple calculations simultaneously.
In the experiment the team raised the temperature of a system, in which information is encoded in the nuclei of phosphorus atoms in silicon, from -269 °C to 25 °C and demonstrated that the superposition states survived at this balmy temperature for 39 minutes – outside of silicon the previous record for such a state’s survival at room temperature was around two seconds. The team even found that they could manipulate the qubits as the temperature of the system rose, and that they were robust enough for this information to survive being ‘refrozen’ (the optical technique used to read the qubits only works at very low temperatures).
‘39 minutes may not seem very long but as it only takes one-hundred-thousandth of a second to flip the nuclear spin of a phosphorus ion – the type of operation used to run quantum calculations – in theory over 20 million operations could be applied in the time it takes for the superposition to naturally decay by one percent. Having such robust, as well as long-lived, qubits could prove very helpful for anyone trying to build a quantum computer,’ said Stephanie Simmons of Oxford University’s Department of Materials, an author of the paper.
‘This opens up the possibility of truly long-term coherent information storage at room temperature,’ said Mike Thewalt of Simon Fraser University.
The team began with a sliver of silicon doped with small amounts of other elements, including phosphorus. Quantum information was encoded in the nuclei of the phosphorus atoms: each nucleus has an intrinsic quantum property called ‘spin’, which acts like a tiny bar magnet when placed in a magnetic field. Spins can be manipulated to point up (0), down (1), or any angle in between, representing a superposition of the two other states.
The team prepared their sample at just 4 °C above absolute zero (-269 °C) and placed it in a magnetic field. Additional magnetic field pulses were used to tilt the direction of the nuclear spin and create the superposition states. When the sample was held at this cryogenic temperature, the nuclear spins of about 37 per cent of the ions – a typical benchmark to measure quantum coherence – remained in their superposition state for three hours. The same fraction survived for 39 minutes when the temperature of the system was raised to 25 °C.
‘These lifetimes are at least ten times longer than those measured in previous experiments,’ said Stephanie Simmons. ‘We've managed to identify a system that seems to have basically no noise. They're high-performance qubits.’
There is still some work ahead before the team can carry out large-scale quantum computations. The nuclear spins of the 10 billion or so phosphorus ions used in this experiment were all placed in the same quantum state. To run calculations, however, physicists will need to place different qubits in different states. ‘To have them controllably talking to one another – that would address the last big remaining challenge,’ said Simmons.
Notes:
A report of the research, entitled ‘Room-Temperature Quantum Bit Storage Exceeding 39 Minutes Using Ionized Donors in Silicon-28’, is published in this week’s Science.
To learn more about quantum information science at Oxford University go to Oxford Quantum.
D-Wave Two™ Quantum Computer Selected for New Quantum Artificial Intelligence Initiative
System to be Installed at NASA's Ames Research Center, and Operational in Q3
BURNABY, British Columbia and PALO ALTO, Calif., May 16, 2013 /PRNewswire/ -- D-Wave Systems Inc., the world's first commercial quantum computing company, today announced that its new 512-qubit quantum computer, the D-Wave Two, will be installed at the new Quantum Artificial Intelligence Lab, a collaboration among NASA, Google and the Universities Space Research Association (USRA). The purpose of this effort is to use quantum computing to advance machine learning in order to solve some of the most challenging computer science problems. Installation has already begun at NASA's Ames Research Center in Moffett Field, California, and the system is expected to be available to researchers during Q3.
New Quantum Artificial Intelligence Initiative
Researchers at Google, NASA and USRA expect to use the D-Wave system to develop applications for a broad range of complex problems such as machine learning, web search, speech recognition, planning and scheduling, search for exoplanets, and support operations in mission control centers. Via USRA the system will also be available to the broader U.S. academic community.
"D-Wave has made significant strides in the technology, application and now commercialization of quantum computing," saidSteve Conway, IDC research vice president for high performance computing. "The order for a D-Wave Two system for the initiative launched by NASA, Google and USRA attests to the revolutionary potential of this fundamentally different approach to computing for both industry and government. HPC buyers and users are looking for ways to speed up their applications beyond what contemporary technologies can deliver. IDC believes organizations that depend on leading-edge technology would do well to begin exploring the possibilities for quantum computing."
As part of the selection process, Google, NASA and USRA created a series of benchmark and acceptance tests that the new D-Wave 512-qubit system was required to pass before the installation at NASA Ames could proceed. In all cases, the D-Wave Two system met or exceeded the required performance specifications, in some cases by a large margin.
"We are extremely pleased to make this announcement," stated Vern Brownell, CEO of D-Wave. "Three world class organizations and their research teams will use the D-Wave Two to develop real world applications and to support research from leading academic institutions. This joint effort shows that quantum computing has expanded beyond the theoretical realm and into the worlds of business and technology."
About D-Wave Systems Inc.
Founded in 1999, D-Wave's mission is to integrate new discoveries in physics and computer science into breakthrough approaches to computation that serves business. The company's flagship product, the 512-qubit D-Wave Two™ computer, is built around a novel type of superconducting processor that uses quantum mechanics to massively accelerate computation. The NASA/Google/USRA installation marks a significant broadening of D-Wave's customer base, and comes on the heels of Lockheed-Martin's purchase of an upgrade of their 128-qubit D-Wave One™ system to a 512-qubit D-Wave Two earlier in this year. With headquarters near Vancouver, Canada, the D-Wave U.S. offices are located in Palo Alto, California. D‑Wave has a blue-chip investor base including Bezos Expeditions, Business Development Bank of Canada, Draper Fisher Jurvetson, Goldman Sachs, Growthworks, Harris & Harris Group, In-Q-Tel, International Investment and Underwriting, and Kensington Partners Limited.
IBM Research Advances Device Performance for Quantum Computing
- Latest results bring device performance near the minimum requirements for implementation of a practical quantum computer.
- Scaling up to hundreds or thousands of quantum bits becomes a possibility.
YORKTOWN HEIGHTS, N.Y., Feb. 28, 2012 /PRNewswire/ -- Scientists at IBM Research (NYSE: IBM) / (#ibmresearch) have achieved major advances in quantum computing device performance that may accelerate the realization of a practical, full-scale quantum computer. For specific applications, quantum computing, which exploits the underlying quantum mechanical behavior of matter, has the potential to deliver computational power that is unrivaled by any supercomputer today.
IBM Research Advances Device Performance for Quantum Computing
Using a variety of techniques in the IBM labs, scientists have established three new records for reducing errors in elementary computations and retaining the integrity of quantum mechanical properties in quantum bits (qubits) – the basic units that carry information within quantum computing. IBM has chosen to employ superconducting qubits, which use established microfabrication techniques developed for silicon technology, providing the potential to one day scale up to and manufacture thousands or millions of qubits.
The Possibilities of Quantum Computing
The special properties of qubits will allow quantum computers to work on millions of computations at once, while desktop PCs can typically handle minimal simultaneous computations. For example, a single 250-qubit state contains more bits of information than there are atoms in the universe.
These properties will have wide-spread implications foremost for the field of data encryption where quantum computers could factor very large numbers like those used to decode and encode sensitive information.
"The quantum computing work we are doing shows it is no longer just a brute force physics experiment. It's time to start creating systems based on this science that will take computing to a new frontier," says IBM scientist Matthias Steffen, manager of the IBM Research team that's focused on developing quantum computing systems to a point where it can be applied to real-world problems.
Other potential applications for quantum computing may include searching databases of unstructured information, performing a range of optimization tasks and solving previously unsolvable mathematical problems.
How Quantum Computing Works
The most basic piece of information that a typical computer understands is a bit. Much like a light that can be switched on or off, a bit can have only one of two values: "1" or "0". For qubits, they can hold a value of "1" or "0" as well as both values at the same time. Described as superposition, this is what allows quantum computers to perform millions of calculations at once.
One of the great challenges for scientists seeking to harness the power of quantum computing is controlling or removing quantum decoherence – the creation of errors in calculations caused by interference from factors such as heat, electromagnetic radiation, and materials defects. To deal with this problem, scientists have been experimenting for years to discover ways of reducing the number of errors and of lengthening the time periods over which the qubits retain their quantum mechanical properties. When this time is sufficiently long, error correction schemes become effective making it possible to perform long and complex calculations.
There are many viable systems that can potentially lead to a functional quantum computer. IBM is focusing on using superconducting qubits that will allow a more facile transition to scale up and manufacturing.
IBM has recently been experimenting with a unique "three dimensional" superconducting qubit (3D qubit), an approach that was initiated at Yale University. Among the results, the IBM team has used a 3D qubit to extend the amount of time that the qubits retain their quantum states up to 100 microseconds – an improvement of 2 to 4 times upon previously reported records. This value reaches just past the minimum threshold to enable effective error correction schemes and suggests that scientists can begin to focus on broader engineering aspects for scalability.
In separate experiments, the group at IBM also demonstrated a more traditional "two-dimensional" qubit (2D qubit) device and implemented a two-qubit logic operation – a controlled-NOT (CNOT) operation, which is a fundamental building block of a larger quantum computing system. Their operation showed a 95 percent success rate, enabled in part due to the long coherence time of nearly 10 microseconds. These numbers are on the cusp of effective error correction schemes and greatly facilitate future multi-qubit experiments.
IBM and Quantum Computing Leadership
The implementation of a practical quantum computer poses tremendous scientific and technological challenges, but all results taken together paint an optimistic picture of rapid progress in that direction.
Core device technology and performance metrics at IBM have undergone a series of amazing advancements by a factor of 100 to 1,000 times since the middle of 2009, culminating in the recent results that are very close to the minimum requirements for a full-scale quantum computing system as determined by the world-wide research community. In these advances, IBM stresses the importance and value of the ongoing exchange of information and learning with the quantum computing research community as well as direct university and industrial collaborations.
"The superconducting qubit research led by the IBM team has been progressing in a very focused way on the road to a reliable, scalable quantum computer. The device performance that they have now reported brings them nearly to the tipping point; we can now see the building blocks that will be used to prove that error correction can be effective, and that reliable logical qubits can be realized," observes David DiVincenzo, professor at the Institute of Quantum Information, Aachen University and Forschungszentrum Juelich.
Based on this progress, optimism about superconducting qubits and the possibilities for a future quantum computer are rapidly growing. While most of the work in the field to date has focused on improvements in device performance, efforts in the community now must now include systems integration aspects, such as assessing the classical information processing demands for error correction, I/O issues, feasibility, and costs with scaling.
IBM envisions a practical quantum computing system as including a classical system intimately connected to the quantum computing hardware. Expertise in communications and packaging technology will be essential at and beyond the level presently practiced in the development of today's most sophisticated digital computers.
While not a new development, quantum computing is the next target for intrepid developers, most of whom are physicists and scientists rather than programmers and inventors. The hardware needed to run a quantum algorithm is finicky at best and is downright terrifying to maintain. But what is quantum computing and what goes into making a quantum computer?
What is a Quantum Computer?
Quantum What?
A conventional modern PC is capable of two binary states, these being a one or a zero. These bits make up all of the information that your stock home computer hold on its hard drive. However, a quantum computer is somewhat different. Rather than being able to operate in states of one or zero, it is able to be in both states at once or in superposition as well as every state in between.
Rather than binary bits, these machines use qubits. A quantum computer makes use of principles of quantum mechanics, notably quantum interference in the most widespread design models, rather than conventional physics in order to operate. Just to illustrate the difference in processing between your home PC and something quantum, a 30-qubit system will run at the real world equivalent of a conventional unit running at 10 teraflops. Since home users have got access to processing in the gigaflop range at the moment, this is a huge jump in power. Maybe Crysis will finally run on Ultra.
Does it Work?
It would appear that quantum computers are in fact a reality. They are very difficult to maintain, construct and understand. Unless you are one of the geniuses involved in the project, that is. Mostly theoretical at this point, there have been major advances in the field of quantum computing. In March 2000, scientists at the Los Alamos National Laboratory announced that they had constructed a 7-qubit quantum computer inside a drop a liquid. The liquid in question was either alanine (used to analyze quantum state decay) or the tongue busting trichloroethylene (used for quantum error correction) and the state of the qubits in question is read by nuclear magnetic resonance or NMR, which is a method of indirectly measuring the state of a qubit.
The problem with measuring a qubit directly is that an accurate reading will drop a qubit out of superposition (should it be in that state) and turn your quantum computer into a conventional one.
The methods used in quantum computing in order to create results are far too lengthy to fully explain almost everywhere outside their scientific literature and the systems being created also vary, making a broad assessment impossible. Very much in their infancy, there are strides forward being made. From 2000 and Los Alamos's 7-qubit machine there have been; another 7-qubit machine demonstrated by IBM and Stanford University; the development of the first qubit using ion traps in 2005 and most recently a 16-qubit quantum computer that was demonstrated by D-Wave Systems in late 2007. Rather than just being a theoretical construct, this computer was able to solve Sudoku puzzles and other problems that were demonstrated.
Sooner than Expected?
D-Wave Systems in particular are raring to get a working model of a quantum computer on the market as soon as possible. Their planned system will not be a fully functional one but will rather be what one quantum algorithm designer calls 'special purpose noisy piece of hardware' that could take up the task of running physical simulations that are impossible on conventional silicon technology.
Looking forward to the future of computing quantum computing has the potential to far outstrip anything that a home user could have imagined. Such processing power could even be put to use creating a true life simulation, a form of virtual reality indistinguishable from reality itself.
