Category Archives: Quantum Computing
Quantum Internet Is 13 Years Away. Wait, What’s Quantum Internet? – WIRED
A year ago this week, Chinese physicists launched the worlds first quantum satellite. Unlike the dishes that deliver your Howard Stern and cricket tournaments, this 1,400-pound behemoth doesnt beam radio waves. Instead, the physicists designed it to send and receive bits of information encoded in delicate photons of infrared light. Its a test of a budding technology known as quantum communications, which experts say could be far more secure than any existing info relay system.
Theyve kept the satellite busy. This summer, the group has published several papers in Science and Nature in which they sent so-called entangled photons between the satellitenicknamed Micius, after an ancient Chinese philosopherand multiple ground stations. If quantum communications were like mailing a letter, entangled photons are kind of like the envelope: They carry the message and keep it secure. Jian-Wei Pan of the University of Science and Technology of China, who leads the research on the satellite, has said that he wants to launch more quantum satellites in the next five years. By 2030, hes hoping that quantum communications will span multiple countries. In 13 years, you can expect quantum internet.
Which means what exactly? In the simplest terms, it will involve multiple parties pinging information at each other in the form of quantum signalsbut experts havent really figured out what it will do beyond that. Quantum internet is a vague term, says physicist Thomas Jennewein of the University of Waterloo. People, including myself, like to use it. However, theres no real definition of what it means.
Thats because so much of the technology is still in its infancy. Physicists still cant control and manipulate quantum signals very well. Pans quantum satellite may have been able to send and receive signals, but it cant really store quantum informationthe best quantum memories can only preserve information for less than an hour. And researchers still dont know what material makes the best quantum memory.
They also arent sure how theyd transmit signals efficiently between the nodes of the future quantum web. Blanketing Earth in quantum satellites is expensivePans cost $100 million. Ground-based transmission via optical fiber isnt perfect either: Quantum signals die out after about 60 miles of transmission. The signals cant be amplified like an electronic signal, either. So researchers are developing special devices known as quantum repeaters that can transmit signals over long distances.
That research will take time. Even if Pan gets his international network up and running by 2030, its not like itll be handling your social media feed by then. And maybe we wouldnt want it to, either. Just because something is quantum doesnt mean its automatically better, says physicist Kai-Mei Fu of the University of Washington. In many cases, it doesnt make a lot of sense to communicate quantum mechanically, she says. Quantum signals have weird properties like superposition, where a particles location is a probability distribution, and it has no precise location. Most communication between humans would still be far easier to express by encoding regular old 1s and 0s in blips of electricity.
So whats the point of it? In the near future, the quantum internet could be a specialized branch of the regular internet. Research groups all over the world are currently developing chips that might allow a classical computer to connect to a quantum network. People would use classical computing most of the time and hook up to the quantum network only for specific tasks.
For example, says physicist Renato Renner of ETH Zurich, you might connect a classical personal computer to a quantum network to send a message using quantum cryptographyarguably the most mature quantum technology. In quantum cryptography, a sender uses a cryptographic key encoded in a quantum signal to encrypt a message. According to the laws of quantum mechanics, if someone tried to intercept the key, they would destroy it.
The quantum internet could also be useful for potential quantum computing schemes, says Fu. Companies like Google and IBM are developing quantum computers to execute specific algorithms faster than any existing computer. Instead of selling people personal quantum computers, theyve proposed putting their quantum computer in the cloud, where users would log into the quantum computer via the internet. While running their computations, they might want to transmit quantum-encrypted information between their personal computer and the cloud-based quantum computer. Users might not want to send their information classically, where it could be eavesdropped, Fu says.
But itll take a whileif everbefore a quantum network gets as big or as versatile as our current internet. To get to the point where billions of quantum devices are connected to the same network, where any connected device can talk to any other device, wed be lucky to see it in our lifetime, Jennewein says.
The incremental progress doesnt bother Renner. Hes just excited that these experiments inspire physicists to think about quantum mechanics in new ways. All these developments will certainly help our understanding of physics, he says. As a physicist, I want to stress that we are not only application-driven, but also driven by our search for understanding. As consumers, though, well be waiting for our new gadgets.
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Quantum Internet Is 13 Years Away. Wait, What's Quantum Internet? - WIRED
Quantum Computing Is Real, and D-Wave Just Open … – WIRED
Quantum computing is real. But it's also hard. So hard that only a few developers, usually trained in quantum physics, advanced mathematics, or most likely both, can actually work with the few quantum computers that exist. Now D-Wave, the Canadian company behind the quantum computer that Google and NASA have been testing since 2013, wants to make quantum computing a bit easier through the power of open source software.
Traditional computers store information in "bits," which can represent either a "1" or a "0." Quantum computing takes advantage of quantum particles in a strange state called "superposition," meaning that the particle is spinning in two directions at once. Researchers have learned to take advantage of these particles to create what they call "qubits," which can represent both a 1 and a 0 at the same time. By stringing qubits together, companies like D-Wave hope to create computers that are exponentially faster than today's machines.
IBM demonstrated a working quantum computer in 2000 and continues to improve on its technology. Google is working on its own quantum computer and also teamed up with NASA to test D-Wave's system in 2013. Lockheed Martin and the Los Alamos National Laboratory are also working with D-Wave machines. But today's quantum computers still aren't practical for most real-world applications. qubits are fragile and can be easily knocked out of the superposition state. Meanwhile, quantum computers are extremely difficult to program today because they require highly specialized knowledge.
"D-Wave is driving the hardware forward," says D-Wave International president Bo Ewald. "But we need more smart people thinking about applications, and another set thinking about software tools."
That's where the company's new software tool Qbsolv comes in. Qbsolv is designed to help developers program D-Wave machines without needing a background in quantum physics. A few of D-Wave's partners are already using the tool, but today the company released Qbsolv as open source, meaning anyone will be able to freely share and modify the software.
"Not everyone in the computer science community realizes the potential impact of quantum computing," says Fred Glover, a mathematician at the University of Colorado, Boulder who has been working with Qbsolv. "Qbsolv offers a tool that can make this impact graphically visible, by getting researchers and practitioners involved in charting the future directions of quantum computing developments."
Qbsolv joins a small but growing pool of tools for would-be quantum computer programmers. Last year Scott Pakin of Los Alamos National Laboratoryand one of Qbsolv's first usersreleased another free tool called Qmasm, which also eases the burden of writing code for D-Wave machines by freeing developers from having to worry about addressing the underlying hardware. The goal, Ewald says, is to kickstart a quantum computing software tools ecosystem and foster a community of developers working on quantum computing problems. In recent years, open source software has been the best way to build communities of both independent developers and big corporate contributors.
Of course to actually run the software you create with these tools, you'll need access to one of the very few existing D-Wave machines. In the meantime, you can download a D-Wave simulator that will let you test the software on your own computer. Obviously this won't be the same as running it on a piece of hardware that uses real quantum particles, but it's a start.
Last year, IBM launched a cloud-based service that enables people to run their own programs on the company's quantum computer. But at least for the moment, Qbsolv and Qmasm will only be useful for creating applications for D-Wave's hardware. D-Wave's machines take a radically different approach to computing than traditional computers, or even other quantum computing prototypes. While most computersranging from your smartphone to IBM's quantum computerare general purpose, meaning they can be programmed to solve all sort of problems, D-Wave's machines are designed for a single purpose: solving optimization problems. The classic example is known as the traveling salesman problem: calculating the shortest route that passes through a list of specific locations.
In the early days, critics wondered whether D-Wave's expensive machines were even quantum computers at all, but most researchers now seem to agree that the machines do exhibit quantum behavior. "There are very few doubts left that there are indeed quantum effects at work and that they play a meaningful computational role," University of Southern California researcher Daniel Lidar told us in 2015 after Google and NASA released a research paper detailing some of their work with the D-Wave. The big question now is whether D-Waves are actually any faster than traditional computers, and if its unique approach is better than that taken by IBM and other researchers.
Pakin says his team are believers in D-Waves potential, even though they admit its systems might not yet offer performance improvements except in very narrow cases. He also explains that D-Wave's computers don't necessarily provide the most efficient answers to an optimization problemor even a correct one. Instead, the idea is to provide solutions that are probably good, if not perfect solutions, and to do it very quickly. That narrows the D-Wave machines' usefulness to optimization problems that need to be solved fast but don't need to be perfect. That could include many artificial intelligence applications.
Ideally, however, the hardware and software will improve to the point that other types of computing problems can be translated into optimization problems, and Qbsolv and Qmasm are steps towards building exactly that. But to get there, they'll need more than just open source software. They'll need an open source community.
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Quantum Computing Is Real, and D-Wave Just Open ... - WIRED
Blind quantum computing for everyone – Phys.org – Phys.Org
Credit: CC0 Public Domain
(Phys.org)For the first time, physicists have demonstrated that clients who possess only classical computersand no quantum devicescan outsource computing tasks to quantum servers that perform blind quantum computing. "Blind" means the quantum servers do not have full information about the tasks they are computing, which ensures that the clients' computing tasks are kept secure. Until now, all blind quantum computing demonstrations have required that clients have their own quantum devices in order to delegate tasks for blind quantum computing.
The team of physicists, led by Jian-Wei Pan and Chao-Yang Lu at the University of Science and Technology of China, have published a paper on the demonstration of blind quantum computing for classical clients in a recent issue of Physical Review Letters.
"We have demonstrated for the first time that a fully classical client can delegate a quantum computation to untrusted quantum servers while maintaining full privacy," Lu told Phys.org.
The idea behind blind quantum computing is that, while there are certain computing tasks that quantum computers can perform exponentially better than classical computers, quantum computing still involves expensive, complex hardware that will make it inaccessible for most clients. So instead of everyone owning their own quantum computing devices, blind quantum computing makes it possible for clients to outsource their computing tasks to quantum servers that do the job for them. Ensuring that the quantum computing is performed blindly is important, since many of the potential applications of quantum computing will likely require a high degree of security.
Although several blind quantum computing protocols have been performed in the past few years, they have all required that the clients have the ability to perform certain quantum tasks, such as prepare or measure qubit states. Eliminating this requirement will provide greater access to blind quantum computing, since most clients only have classical computing systems.
In the new study, the physicists experimentally demonstrated that a classical client can outsource a simple problem (factoring the number 15) to two quantum servers that do not fully know what problem they are solving. This is because each server completes part of the task, and it is physically impossible for the servers to communicate with each other. To ensure that the quantum servers are performing their tasks honestly, the client can give them "dummy tasks" that are indistinguishable from the real task to test their honesty and correctness.
The researchers expect that the new method can be scaled up for realizing secure, outsourced quantum computing, which could one day be implemented on quantum cloud servers and make the power of quantum computing widely available.
"Blind quantum computing protocol is an important privacy-preserving technique for future secure quantum cloud computing and secure quantum networks," Lu said. "Applying our implemented blind quantum computing protocol, classical clients could delegate computation tasks to servers 'in the cloud' blindly and correctly without directly owning quantum devices. It saves resources and makes scalable quantum computing possible."
In the future, the physicists want to make blind quantum computing even easier for clients by further reducing the requirements.
"We plan to study more robust blind quantum computing protocols with fewer required resources and fewer constraints theoretically and experimentally," Lu said. "We will also explore blind quantum computing for more application scenarios, such as multi-user blind quantum computing, publicly verifiable quantum computing, and secure multi-party quantum computing."
Explore further: Developing quantum algorithms for optimization problems
More information: He-Liang Huang et al. "Experimental Blind Quantum Computing for a Classical Client." Physical Review Letters. DOI: 10.1103/PhysRevLett.119.050503 , Also at arXiv:1707.00400 [quant-ph]
2017 Phys.org
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Blind quantum computing for everyone - Phys.org - Phys.Org
Quantum Computing Market Worth 495.3 Million USD by 2023 | 08 … – Markets Insider
PUNE, India, August 9, 2017 /PRNewswire/ --
According to the new market research report on the"Quantum Computing Marketby Revenue Source, Application (Simulation, Optimization, and Sampling), Industry (Defense, Banking & Finance, Energy & Power, Chemicals, and Healthcare & Pharmaceuticals), and Geography - Global Forecast to 2023", published by MarketsandMarkets this market is expected to be valued at USD 495.3 Million by 2023, at a CAGR of 29.04% between 2017 and 2023. The major factors driving the growth of the quantum computing market include increasing incidences of cybercrimes, early adoption of quantum computing in the automotive and defense industry, and increasing investment by government entities in the quantum computing market.
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Browse33 Market Data Tables and29 Figures spread through109 Pages and in-depth TOC on"Quantum Computing Market - Global Forecast to 2023"
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Revenue realization from software would led quantum computing market during the forecast period
The software acts as an interface between the user and the quantum computer. The quantum computer offered by the key players is coupled with the appropriate software. The software are offered by a range of market players, such as D-Wave Systems Inc. (Canada), 1QB Information Technologies Inc. (Canada), QxBranch LLC (US), and QC Ware Corp. (US), to improve the operational efficiencies of the quantum computer. In the quantum computing market, the software segment is expected to earn maximum revenue during the forecast period. Need for compatible software in upcoming quantum hardware and services would act as strong drivers for the growth of quantum computing market for the software segment during the forecast period.
The energy & power industry would grow at the highest rate during the forecast period
The quantum computing market in the energy & power industry is expected to witness a CAGR of 39.11% from 2017 to 2023. This growth is mainly attributed to the lucrative opportunities present in the nuclear and renewable sector. Applications such as energy exploration, seismic survey optimization, and reservoir optimization are expected to lead this industry in the quantum computing market.
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Simulation expected to hold the largest share of the overall quantum computing market in 2017
Simulation is used in various industries such as healthcare, automotive, entertainment, banking & finance, and defense. The companies, such as D-Wave Systems Inc. (Canada), 1QB Information Technologies Inc. (Canada), and QxBranch, LLC (US), would be providing a platform to enhance the availability, usability, and accessibility of simulation in the quantum computing market in the next 4 years. Moreover, developments in this area such as the launch of quantum computing simulator by QxBranch LLC (US) for the Commonwealth Bank of Australia would drive the growth of the quantum computing market for the simulation application.
Asia Pacific is likely to grow at the highest rate due to the growth of developing and developed economies in this region
The quantum computing market in Asia Pacific (APAC) is expected to be commercialized by 2019. The growth of quantum computing in APAC would be mainly driven by China, Japan, and South Korea in various industries such as defense, healthcare & pharmaceuticals, chemicals, banking & finance, and energy & power.
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The report profiles the most promising players in this market. The key players in this market are D-Wave Systems Inc. (Canada), 1QB Information Technologies Inc. (Canada), QxBranch LLC (US), and QC Ware Corp. (US) and Research at Google-Google Inc. (US).
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Quantum Computing Market Worth 495.3 Million USD by 2023 | 08 ... - Markets Insider
China uses a quantum satellite to transmit potentially unhackable data – CNBC
China has demonstrated a world first by sending data over long distances using satellites which is potentially unhackable, laying the basis for next generation encryption based on so-called "quantum cryptography.
Last August, China launched a quantum satellite into space, a move which was called a "notable advance" by the Pentagon.
Using this satellite, Chinese researchers at the Quantum Experiments at Space Scale (QUESS) project, were able to transmit secret messages from space to Earth at a further distance than ever before.
The technology is called quantum key distribution (QKD). Typical encryption relies on traditional mathematics and while for now it is more or less adequate and safe from hacking, the development of quantum computing threatens that. Quantum computing refers to a new era of faster and more powerful computers, and the theory goes that they would be able to break current levels of encryption.
That's why China is looking to use quantum cryptography for encryption. QKD works by using photons the particles which transmit light to transfer data.
"QKD allows two distant users, who do not share a long secret key initially, to produce a common, random string of secret bits, called a secret key," the researchers explained in a paper published in the journal Nature on Wednesday.
"Using the one-time pad encryption this key is proven to be secure to encrypt (and decrypt) a message, which can then be transmitted over a standard communication channel."
State news agency Xinhua called the encryption "unbreakable" and that's mainly because of the way data is carried via the photon. A photon cannot be perfectly copied and any attempt to measure it will disturb it. This means that a person trying to intercept the data will leave a trace.
"Any eavesdropper on the quantum channel attempting to gain information of the key will inevitably introduce disturbance to the system, and can be detected by the communicating users," the researchers said.
The implications could be huge for cybersecurity, making businesses safer, but also making it more difficult for governments to hack into communication.
China successfully sent the data over a distance of 1,200 kilometers from space to Earth, which is up to 20 orders of magnitudes more efficient than that expected using an optical fiber of the same length, the researchers claimed. It's also further than the current limits of a few hundred kilometers.
"That, for instance, can meet the demand of making an absolute safe phone call or transmitting a large amount of bank data," Pan Jianwei, lead scientist of QUESS, told Xinhua.
The Chinese government has made the development of the space sector a key priority. For example, it has laid out plans to get to Mars by 2020 and become a major space power by 2030.
And China has global ambitions for its QKD. It sees its satellite system interacting with ground-based QKD networks to create a global secure network.
"We can thus envision a space-ground integrated quantum network, enabling quantum cryptography most likely the first commercial application of quantum information useful at a global scale," the researchers said.
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China uses a quantum satellite to transmit potentially unhackable data - CNBC
Physicists Take Big Step Towards Quantum Computing and … – Universe Today
Quantum entanglement remains one of the most challenging fields of study for modern physicists. Described by Einstein as spooky action at a distance, scientists have long sought to reconcile how this aspect of quantum mechanics can coexist with classical mechanics. Essentially, the fact that two particles can be connected over great distances violates the rules of locality and realism.
Formally, this is a violation of Bells Ineqaulity, a theory which has been used for decades to show that locality and realism are valid despite being inconsistent with quantum mechanics. However, in a recent study, a team of researchers from the Ludwig-Maximilian University (LMU) and the Max Planck Institute for Quantum Optics in Munich conducted tests which once again violate Bells Inequality and proves the existence of entanglement.
Their study, titled Event-Ready Bell Test Using Entangled Atoms Simultaneously Closing Detection and Locality Loopholes, was recently published in the Physical Review Letters. Led by Wenjamin Rosenfeld, a physicist at LMU and the Max Planck Institute for Quantum Optics, the team sought to test Bells Inequality by entangling two particles at a distance.
John Bell, the Irish physicist who devised a test to show that nature does not hide variables as Einstein had proposed. Credit: CERN
Bells Inequality (named after Irish physicist John Bell, who proposed it in 1964) essentially states that properties of objects exist independent of being observed (realism), and no information or physical influence can propagate faster than the speed of light (locality). These rules perfectly described the reality we human beings experience on a daily basis, where things are rooted in a particular space and time and exist independent of an observer.
However, at the quantum level, things do not appear to follow these rules. Not only can particles be connected in non-local ways over large distances (i.e. entanglement), but the properties of these particles cannot be defined until they are measured. And while all experiments have confirmed that the predictions of quantum mechanics are correct, some scientists have continued to argue that there are loopholes that allow for local realism.
To address this, the Munich team conducted an experiment using two laboratories at LMU. While the first lab was located in the basement of the physics department, the second was located in the basement of the economics department roughly 400 meters away. In both labs, teams captured a single rubidium atom in an topical trap and then began exciting them until they released a single photon.
As Dr. Wenjamin Rosenfeld explained in an Max Planck Institute press release:
Our two observer stations are independently operated and are equipped with their own laser and control systems. Because of the 400 meters distance between the laboratories, communication from one to the other would take 1328 nanoseconds, which is much more than the duration of the measurement process. So, no information on the measurement in one lab can be used in the other lab. Thats how we close the locality loophole.
The experiment was performed in two locations 398 meters apart at the Ludwig Maximilian University campus in Munich, Germany. Credit: Rosenfeld et al/American Physical Society
Once the two rubidium atoms were excited to the point of releasing a photon, the spin-states of the rubidium atoms and the polarization states of the photons were effectively entangled. The photons were then coupled into optical fibers and guided to a set-up where they were brought to interference. After conducting a measurement run for eight days, the scientists were able to collected around 10,000 events to check for signs entanglement.
This would have been indicated by the spins of the two trapped rubidium atoms, which would be pointing in the same direction (or in the opposite direction, depending on the kind of entanglement). What the Munich team found was that for the vast majority of the events, the atoms were in the same state (or in the opposite state), and that there were only six deviations consistent with Bells Inequality.
These results were also statistically more significant than those obtained by a team of Dutch physicists in 2015. For the sake of that study, the Dutch team conducted experiments using electrons in diamonds at labs that were 1.3 km apart. In the end, their results (and other recent tests of Bells Inequality) demonstrated that quantum entanglement is real, effectively closing the local realism loophole.
As Wenjamin Rosenfeld explained, the tests conducted by his team also went beyond these other experiments by addressing another major issue. We were able to determine the spin-state of the atoms very fast and very efficiently, he said. Thereby we closed a second potential loophole: the assumption, that the observed violation is caused by an incomplete sample of detected atom pairs.
By obtaining proof of the violation of Bells Inequality, scientists are not only helping to resolve an enduring incongruity between classical and quantum physics. They are also opening the door to some exciting possibilities. For instance, for years, scientist have anticipated the development of quantum processors, which rely on entanglements to simulate the zeros and ones of binary code.
Computers that rely on quantum mechanics would be exponentially faster than conventional microprocessors, and would ushering in a new age of research and development. The same principles have been proposed for cybersecurity, where quantum encryption would be used to cypher information, making it invulnerable to hackers who rely on conventional computers.
Last, but certainly not least, there is the concept of Quantum Entanglement Communications, a method that would allow us to transmit information faster than the speed of light. Imagine the possibilities for space travel and exploration if we are no longer bound by the limits of relativistic communication!
Einstein wasnt wrong when he characterized quantum entanglements as spooky action. Indeed, much of the implications of this phenomena are still as frightening as they are fascinating to physicists. But the closer we come to understanding it, the closer we will be towards developing an understanding of how all the known physical forces of the Universe fit together aka. a Theory of Everything!
Further Reading: LMU, Physical Review Letters
By Matt Williams- Matt Williams is the Curator of Universe Today's Guide to Space. He is also a freelance writer, a science fiction author and a Taekwon-Do instructor. He lives with his family on Vancouver Island in beautiful British Columbia.
Bell's Inequality, classical physics, Featured, Max Planck Institute for Quantum Optics, quantum entanglement, quantum mechanics
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Physicists Take Big Step Towards Quantum Computing and ... - Universe Today
Why you might trust a quantum computer with secretseven over … – Phys.Org
It may be possible to control a quantum computer over the internet without revealing what you are calculating, thanks to the many possible ways that information can flow through a computation. That's the conclusion of researchers in Singapore and Australia who studied the measurement-based model of quantum computing, reported 11 July in the open-access journal Physical Review X. Credit: Timothy Yeo / Centre for Quantum Technologies, National University of Singapore
Here's the scenario: you have sensitive data and a problem that only a quantum computer can solve. You have no quantum devices yourself. You could buy time on a quantum computer, but you don't want to give away your secrets. What can you do?
Writing in Physical Review X on 11 July, researchers in Singapore and Australia propose a way you could use a quantum computer securely, even over the internet. The technique could hide both your data and program from the computer itself. Their work counters earlier hints that such a feat is impossible.
The scenario is not far-fetched. Quantum computers promise new routes to solving problems in cryptography, modelling and machine learning, exciting government and industry. Such problems may involve confidential data or be commercially sensitive.
Technology giants are already investing in building such computersand making them available to users. For example, IBM announced on 17 May this year that it is making a quantum computer with 16 quantum bits accessible to the public for free on the cloud, as well as a 17-qubit prototype commercial processor.
Seventeen qubits are not enough to outperform the world's current supercomputers, but as quantum computers gain qubits, they are expected to exceed the capabilities of any machine we have today. That should drive demand for access.
"We're looking at what's possible if you're someone just interacting with a quantum computer across the internet from your laptop. We find that it's possible to hide some interesting computations," says Joseph Fitzsimons, a Principal Investigator at the Centre for Quantum Technologies (CQT) at the National University of Singapore and Associate Professor at Singapore University of Technology and Design (SUTD), who led the work.
Quantum computers work by processing bits of information stored in quantum states. Unlike the binary bits found in our regular (i.e., classical) computers, each a 0 or 1, qubits can be in superpositions of 0 and 1. The qubits can also be entangled, which is believed to be crucial to a quantum computer's power.
The scheme designed by Fitzsimons and his colleagues brings secrecy to a form of quantum computing driven by measurements.
In this scheme, the quantum computer is prepared by putting all its qubits into a special type of entangled state. Then the computation is carried out by measuring the qubits one by one. The user provides step-wise instructions for each measurement: the steps encode both the input data and the program.
Researchers have shown previously that users who can make or measure qubits to convey instructions to the quantum computer could disguise their computation. The new paper extends that power to users who can only send classical bits - i.e. most of us, for now.
This is surprising because some computer science theorems imply that encrypted quantum computation is impossible when only classical communication is available.
The hope for security comes from the quantum computer not knowing which steps of the measurement sequence do what. The quantum computer can't tell which qubits were used for inputs, which for operations and which for outputs.
"It's extremely exciting. You can use this unique feature of the measurement-based model of quantum computingthe way information flows through the stateas a crypto tool to hide information from the server," says team member Tommaso Demarie of CQT and SUTD.
Although the owner of the quantum computer could try to reverse engineer the sequence of measurements performed, ambiguity about the role of each step leads to many possible interpretations of what calculation was done. The true calculation is hidden among the many, like a needle in a haystack.
The set of interpretations grows rapidly with the number of qubits. "The set of all possible computations is exponentially large - that's one of the things we prove in the paperand therefore the chance of guessing the real computation is exponentially small," says Fitzsimons. One question remains: could meaningful computations be so rare among all the possible ones that the guessing gets easier? That's what the researchers need to check next.
Nicolas Menicucci at the Centre for Quantum Computation and Communication Technology at RMIT University in Melbourne, Australia, and Atul Mantri at SUTD, are coauthors on the work.
"Quantum computers became famous in the '90s with the discovery that they could break some classical cryptography schemesbut maybe quantum computing will instead be known for making the future of cloud computing secure," says Mantri.
Explore further: Refrigerator for quantum computers discovered
More information: Atul Mantri et al, Flow Ambiguity: A Path Towards Classically Driven Blind Quantum Computation, Physical Review X (2017). DOI: 10.1103/PhysRevX.7.031004
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Why you might trust a quantum computer with secretseven over ... - Phys.Org
Quantum-computer node uses two different ion species – physicsworld.com
A node for quantum computing that uses two different species of ion has been unveiled by Chris Monroe and colleagues at the University of Maryland in the US. The system uses a barium ion to communicate externally via light and a ytterbium ion to store quantum information.
Trapped ions show great promise for use in quantum computers because they can store quantum information for long periods of time and can also be made to interact with photons, which serve as carriers of quantum information. A practical quantum-computing node must be able to do both of these things at the same time, and this is a significant challenge because the ions that are very good at storing information are usually not very good for interacting with photons and vice versa.
One possible solution is to use two different types of ion one for storage and one for communications and transfer quantum information between the two. Now, Monroe's team has done just that. A ytterbium ion was chosen as a memory because it can store quantum information for about 1.5s, which is a very long coherence time in the world of quantum computing. This ion is also attractive because it is insensitive to the light used to manipulate the barium ion, which is located just a few microns away in the ion trap.
In contrast, quantum information can only be stored in the barium atom for about 4ms, but this is long enough to both interact with the outside world via a photon and also transfer quantum information to the neighbouring ytterbium ion.
Quantum communication via light was demonstrated by causing the trapped barium ion to emit a photon and then showing that the ion and photon are entangled. The team also showed that quantum information can be transferred between the barium and ytterbium ions via two processes that involve the coupled motions of the ions in the trap.
Writing in Physical Review Letters, the team says that the process could be further improved and implemented in fabricated chip traps, which could ultimately form the basis of a practical quantum computer.
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Quantum-computer node uses two different ion species - physicsworld.com
Quantum Computers vs Bitcoin How Worried Should We Be? – The Merkle
One of the greatestcomputer innovations everyone seems to be eyeing lately is Quantum Computing. In essence, quantum computing exploits quantum mechanics to perform computational tasks far quicker than a traditional computer can. This means that some aspects of Bitcoin could possibly be vulnerable, but how much do we need to worry?
Research and development into quantum computing is accelerating, and the results are both interesting and worrying. Recently MIT scientists built a 5 atom quantum computer which threatens the very foundations of modern computer cryptography. The scientists behind the project are confident that their computer will put todays encryption to shame.
This means that public key encryption which keeps much of Bitcoin secure, could be under threat. If a quantum computer was to be large enough and powerful enough, it could drastically reduce the amount of computational effort needed to discover private keys from public keys. As we all know, the moment private keys are compromised then any coins under control of that key are as good as gone.
Well, surprisingly we do not need to be cashing out our Bitcoin anytime soon. Even this most recent development in quantum computing is a long way away from a computer large enough to threaten public key encryption. However, once quantum computers are large enough to take public keys on, the Bitcoin community will have already developed and implemented a solution to protect coins and the network.
Right now Bitcoin actually has a little bit of quantum resistance built into it. As long as users are changing addresses with every new transaction -which is obviously recommended- then they mitigate the exposure their private keys to being cracked. The speed with which a quantum computer would need to break that key is insane for now as well. It would have to crack the keyup between the time the transaction is signed and when it is packaged into a block. We are a long way from quantum computers working that quickly.
Bitcoin could also implement softfork changes which would update keys to be far more secure and quantum resistant. Currently Lamport signatures are the most favored but do suffer some down sides. They would be incredibly long and have a finite amount of times a transaction can be signed with one key. The latter may help individuals become better with address reuse, but it could be frustrating to some users. Regardless, the likelihood that the Bitcoin community will be able to come up with a solution before the entire network is under attack is pretty high.
There is an interesting opportunity though that such a softfork would create. The original coins held by Satoshi Nakamoto, if unmoved by the time the network was securing itself against quantum computing, would either be threatened or moved. This means that someone could potentially steal Satoshis fortune or force Satoshi to make a move. Either of these things would be huge developments for the Bitcoin community. It would either prove the continued existence of the coins god or show that no one is above being robbed.
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Quantum Computers vs Bitcoin How Worried Should We Be? - The Merkle
Quantum cheques could be a forgery-free way to move money – New Scientist
Its hard to forge what you cant observe
Equinox Graphics/Getty Images
By Matt Reynolds
A quantum upgrade could make old-fashioned cheques the most secure way to send money. Researchers have proven that quantum computers could in theory create and cash cheques that are nearly impossible to forge.
Quantum computers store information using qubits which, unlike the ones and zeros of classical computing, can exist in two states simultaneously. This is known as quantum superposition.
But its impossible to observe a qubit while its in a superposition it collapses into either a one or zero as soon as you measure it. This is what makes quantum cheques so secure. If anyone intercepted a cheque and had a peek inside, they would only be able to see the qubit in its collapsed state.
The idea of quantum currency has been kicking around for decades, but until last year, very few computer scientists had access to quantum computers to test their theories. Now, researchers using IBMs cloud-based quantum computer have run the numbers.
Although this study is only a proof of concept, quantum technology hasnt got far to go until these systems are workable says Prasanta Panigrahi, who led the study at the Indian Institute of Science, Education and Research in Kolkata. Even existing five-qubit quantum computers like the one used in this experiment could eventually be used to issue and verify quantum cheques, he says. But for now, these kinds of transactions cant be scaled to a wide population and they arent exactly the most convenient way of moving cash.
Say Alice wants to pay Bob using a quantum cheque. She would have to go to the bank, verify her identity and then the bank would issue her with two qubits taken from its central quantum computer. These qubits are inextricably linked to the remaining qubits within the banks central computer a quality known as quantum entanglement. Measuring the state of any one qubit in an entangled system will reveal the state of all qubits within that system. The bank can use this entanglement to verify that its coffers were the origin of a quantum cheque.
Alice can then take her qubits and encode one of them with the amount of money she wants to give to Bob. She then gives this qubit to Bob and he takes it to the bank to cash. The bank verifies that its definitely a qubit from its own system, and that it has been encoded by Alice, and cashes the cheque.
Although you cant forge a quantum cheque, there is one weak point in this system, says Subhayan Roy Moulick, a researcher at the University of Oxford who originally proposed the experimental proof. To encode her qubit, Alice has to access it using a passcode, so if someone stole that passcode and her qubit, they could theoretically tamper with the qubit. But as long as the passcode is memorised or securely locked away the risk of tampering is extremely low, says Moulick.
Then theres the problem of transporting qubits. Some of our current quantum computers need huge cooling systems. It is possible to store qubits at room temperature by using diamonds, but Moulick says that a quantum cheque is more likely to be a laptop-sized black box than something you can slip into your pocket.
Scott Aaronson at the University of Texas suggests applying the concept in a slightly different way. If the bank managed the entire transaction, he says, it would still be ultra secure, but there would be no need for anyone to carry around quantum cheques.
However, the real application is a way off, Aaronson says. At the moment, the qubits in the IBM system only last for microseconds at a time. Ideally, Aaronson says, one would like cheques that can last longer than that before being cashed or deposited.
Besides, in this experimental scenario, the bank gives away two qubits every time it issues a cheque. Even if the bank only issued one cheque a day, it would need hundreds of qubits, and quantum computers of that size are still decades away from becoming reality. The current most powerful quantum computers only have 20 qubits, although Google is on track to build a 49-qubit machine by the end of this year.
Erika Andersson at Heriot-Watt University in Edinburgh, UK, thinks that the whole idea is unnecessarily complicated. Instead, quantum computers could be put to better use creating secure keys instead of physical cheques, she says. The bank could authenticate transactions using a technique called quantum key generation, where quantum computers are used to generate shared security keys to verify the identity of the parties involved in the transaction. This would cut out the need for anyone to carry qubits around.
And, unlike qubit cheques, quantum keys are already catching on in the real world. The technology was used to help keep the results of the 2007 Swiss election secure while in 2012 the Chinese government used it to help keep the discussions at the 2012 National Congress away from prying eyes.
Read more: Google on track for quantum computer breakthrough by end of 2017
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Quantum cheques could be a forgery-free way to move money - New Scientist