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Researchers at Princeton University have made an important step forward in the quest to build a quantum computer using silicon components, which are prized for their low cost and versatility compared to the hardware in todays quantum computers. The team showed that a silicon-spin quantum bit (shown in the box) can communicate with another quantum bit located a significant distance away on a computer chip. The feat could enable connections between multiple quantum bits to perform complex calculations. Credit: Felix Borjans, Princeton University

Princeton scientists demonstrate that two silicon quantum bits can communicate across relatively long distances in a turning point for the technology.

Imagine a world where people could only talk to their next-door neighbor, and messages must be passed house to house to reach far destinations.

Until now, this has been the situation for the bits of hardware that make up a silicon quantum computer, a type of quantum computer with the potential to be cheaper and more versatile than todays versions.

Now a team based at Princeton University has overcome this limitation and demonstrated that two quantum-computing components, known as silicon spin qubits, can interact even when spaced relatively far apart on a computer chip. The study was published today (December 25, 2019) in the journal Nature.

The ability to transmit messages across this distance on a silicon chip unlocks new capabilities for our quantum hardware, said Jason Petta, the Eugene Higgins Professor of Physics at Princeton and leader of the study. The eventual goal is to have multiple quantum bits arranged in a two-dimensional grid that can perform even more complex calculations. The study should help in the long term to improve communication of qubits on a chip as well as from one chip to another.

Quantum computers have the potential to tackle challenges beyond the capabilities of everyday computers, such as factoring large numbers. A quantum bit, or qubit, can process far more information than an everyday computer bit because, whereas each classical computer bit can have a value of 0 or 1, a quantum bit can represent a range of values between 0 and 1 simultaneously.

To realize quantum computings promise, these futuristic computers will require tens of thousands of qubits that can communicate with each other. Todays prototype quantum computers from Google, IBM and other companies contain tens of qubits made from a technology involving superconducting circuits, but many technologists view silicon-based qubits as more promising in the long run.

Silicon spin qubits have several advantages over superconducting qubits. The silicon spin qubits retain their quantum state longer than competing qubit technologies. The widespread use of silicon for everyday computers means that silicon-based qubits could be manufactured at low cost.

The challenge stems in part from the fact that silicon spin qubits are made from single electrons and are extremely small.

The wiring or interconnects between multiple qubits is the biggest challenge towards a large scale quantum computer, said James Clarke, director of quantum hardware at Intel, whose team is building silicon qubits using using Intels advanced manufacturing line, and who was not involved in the study. Jason Pettas team has done great work toward proving that spin qubits can be coupled at long distances.

To accomplish this, the Princeton team connected the qubits via a wire that carries light in a manner analogous to the fiber optic wires that deliver internet signals to homes. In this case, however, the wire is actually a narrow cavity containing a single particle of light, or photon, that picks up the message from one qubit and transmits it to the next qubit.

The two qubits were located about half a centimeter, or about the length of a grain of rice, apart. To put that in perspective, if each qubit were the size of a house, the qubit would be able to send a message to another qubit located 750 miles away.

The key step forward was finding a way to get the qubits and the photon to speak the same language by tuning all three to vibrate at the same frequency. The team succeeded in tuning both qubits independently of each other while still coupling them to the photon. Previously the devices architecture permitted coupling of only one qubit to the photon at a time.

You have to balance the qubit energies on both sides of the chip with the photon energy to make all three elements talk to each other, said Felix Borjans, a graduate student and first author on the study. This was the really challenging part of the work.

Each qubit is composed of a single electron trapped in a tiny chamber called a double quantum dot. Electrons possess a property known as spin, which can point up or down in a manner analogous to a compass needle that points north or south. By zapping the electron with a microwave field, the researchers can flip the spin up or down to assign the qubit a quantum state of 1 or 0.

This is the first demonstration of entangling electron spins in silicon separated by distances much larger than the devices housing those spins, said Thaddeus Ladd, senior scientist at HRL Laboratories and a collaborator on the project. Not too long ago, there was doubt as to whether this was possible, due to the conflicting requirements of coupling spins to microwaves and avoiding the effects of noisy charges moving in silicon-based devices. This is an important proof-of-possibility for silicon qubits because it adds substantial flexibility in how to wire those qubits and how to lay them out geometrically in future silicon-based quantum microchips.'

The communication between two distant silicon-based qubits devices builds on previous work by the Petta research team. In a 2010 paper in the journal Science, the team showed it is possible to trap single electrons in quantum wells. In the journal Nature in 2012, the team reported the transfer of quantum information from electron spins in nanowires to microwave-frequency photons, and in 2016 in Science they demonstrated the ability to transmit information from a silicon-based charge qubit to a photon. They demonstrated nearest-neighbor trading of information in qubits in 2017 in Science. And the team showed in 2018 in Nature that a silicon spin qubit could exchange information with a photon.

Jelena Vuckovic, professor of electrical engineering and the Jensen Huang Professor in Global Leadership at Stanford University, who was not involved in the study, commented: Demonstration of long-range interactions between qubits is crucial for further development of quantum technologies such as modular quantum computers and quantum networks. This exciting result from Jason Pettas team is an important milestone towards this goal, as it demonstrates non-local interaction between two electron spins separated by more than 4 millimeters, mediated by a microwave photon. Moreover, to build this quantum circuit, the team employed silicon and germanium materials heavily used in the semiconductor industry.

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Reference: Resonant microwave-mediated interactions between distant electron spins by F. Borjans, X. G. Croot, X. Mi, M. J. Gullans and J. R. Petta, 25 December 2019, Nature.DOI: 10.1038/s41586-019-1867-y

In addition to Borjans and Petta, the following contributed to the study: Xanthe Croot, a Dicke postdoctoral fellow; associate research scholar Michael Gullans; and Xiao Mi, who earned his Ph.D. at Princeton in Pettas group and is now a research scientist at Google.

The study was funded by Army Research Office (grant W911NF-15-1-0149) and the Gordon and Betty Moore Foundations EPiQS Initiative (grant GBMF4535).

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Quantum Computing Breakthrough: Silicon Qubits Interact at Long-Distance - SciTechDaily

Quantum computing has come a long way since its first introduction in the 1980s. Researchers have always been on a lookout for a better way to enhance the ability of quantum computing systems, whether it is in making it cheaper or the quest of making the present quantum computers last longer. With the latest technological advancements in the world of quantum computing which superconducting bits, a new way of improving the world of silicon quantum computing has come to light, making use of the silicon spin qubits for better communication.

Until now, the communication between different qubits was relatively slow. It could be done by passing the messages to the next bit to get the communication over to another chip at a relatively far distance.

Now, researches at Princeton University have explored the idea of two quantum computing silicon components known as silicon spin qubits interacting in a relatively spaced environment, that is with a relatively large distance between them. The study was presented in the journal Nature on December 25, 2019.

The silicon quantum spin qubits give the ability to the quantum hardware to interact and transmit messages across a certain distance which will provide the hardware new capabilities. With transmitting signals over a distance, multiple quantum bits can be arranged in two-dimensional grids that can perform more complex calculations than the existing hardware of quantum computers can do. This study will help in better communications of qubits not only on a chip but also from one to another, which will have a massive impact on the speed.

The computers require as many qubits as possible to communicate effectively with each other to take the full advantage of quantum computings capabilities. The quantum computer that is used by Google and IBM contains around 50 qubits which make use of superconducting circuits. Many researchers believe that silicon-based qubit chips are the future in quantum computing in the long run.

The quantum state of silicon spin qubits lasts longer than the superconducting qubits, which is one of their significant disadvantages (around five years). In addition to lasting longer, silicon which has a lot of application in everyday computers is cheaper, another advantage over the superconducting qubits because these cost a ton of money. Single qubit will cost around $10,000, and thats before you consider research and development costs. With these costs in mind a universal quantum computer hardware alone will be around at least $10bn.

But, silicon spin cubits have their challenges which are part of the fact that they are incredibly small, and by small we mean, these are made out from a single electron. This problem is a huge factor when it comes to establishing an interconnect between multiple qubits when building a large scale computer.

To counter the problem of interconnecting these extremely small silicon spin qubits, the Princeton team connected these qubits with a wire which are similar to the fibre optic (for internet delivery at houses) wires and these wires carry light. This wire contains photon that picks up a message from a single qubit and transmits it the next qubit. To understand this more accurately, if the qubits are placed at a distance of half-centimetre apart from each other for the communication, in real-world, it would be like these qubits are around 750 miles away.

The next step forward for the study was to establish a way of getting qubits and photons to communicate the same language by tuning both the qubits and the photon to the same frequency. Where previously the devices architecture allowed tuning only one qubit to one photon at a time, the team now succeeded in tuning both the qubits independent from each other while still coupling them to the photon.

You have to balance the qubit energies on both sides of the chip with the photon energy to make all three elements talk to each other,

Felix Borjans, a graduate student and first author on the study on what he describes as the challenging part of the work.

The researchers demonstrated entangling of electrons spins in silicon separated by distances more substantial than the device housing, this was a significant development when it comes to wiring these qubits and how to lay them out in silicon-based quantum microchips.

The communication between the distant silicon-based qubits devices builds on the works of Petta research team in 2010 which shows how to trap s single electron in quantum wells and also from works in the journal Nature from the year 2012 (transfer of quantum information from electron spins)

From the paper in Science 2016 (demonstrated the ability to transmit information from a silicon-based charge qubit to a photon), from Science 2017 (nearest-neighbour trading of information in qubits) and 2018 Nature (silicon spin qubit can exchange information with a photon).

This demonstration of interactions between two silicon spin qubits is essential for the further development of quantum tech. This demonstration will help technologies like modular quantum computers and quantum networks. The team has employed silicon and germanium, which is widely available in the market.

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How This Breakthrough Makes Silicon-Based Qubit Chips The Future of Quantum Computing - Analytics India Magazine

Scientists at the University of Bristol and the Technical University of Denmark have achieved quantum teleportation between two computer chips for the first time. The team managed to send information from one chip to another instantly without them being physically or electronically connected, in a feat that opens the door for quantum computers and quantum internet.

This kind of teleportation is made possible by a phenomenon called quantum entanglement, where two particles become so entwined with each other that they can communicate over long distances. Changing the properties of one particle will cause the other to instantly change too, no matter how much space separates the two of them. In essence, information is being teleported between them.

Hypothetically, theres no limit to the distance over which quantum teleportation can operate and that raises some strange implications that puzzled even Einstein himself. Our current understanding of physics says that nothing can travel faster than the speed of light, and yet, with quantum teleportation, information appears to break that speed limit. Einstein dubbed it spooky action at a distance.

Harnessing this phenomenon could clearly be beneficial, and the new study helps bring that closer to reality. The team generated pairs of entangled photons on the chips, and then made a quantum measurement of one. This observation changes the state of the photon, and those changes are then instantly applied to the partner photon in the other chip.

We were able to demonstrate a high-quality entanglement link across two chips in the lab, where photons on either chip share a single quantum state, says Dan Llewellyn, co-author of the study. Each chip was then fully programmed to perform a range of demonstrations which utilize the entanglement. The flagship demonstration was a two-chip teleportation experiment, whereby the individual quantum state of a particle is transmitted across the two chips after a quantum measurement is performed. This measurement utilizes the strange behavior of quantum physics, which simultaneously collapses the entanglement link and transfers the particle state to another particle already on the receiver chip.

The team reported a teleportation success rate of 91 percent, and managed to perform some other functions that will be important for quantum computing. That includes entanglement swapping (where states can be passed between particles that have never directly interacted via a mediator), and entangling as many as four photons together.

Information has been teleported over much longer distances before first across a room, then 25 km (15.5 mi), then 100 km (62 mi), and eventually over 1,200 km (746 mi) via satellite. Its also been done between different parts of a single computer chip before, but teleporting between two different chips is a major breakthrough for quantum computing.

The research was published in the journal Nature Physics.

Source: University of Bristol

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Information teleported between two computer chips for the first time - New Atlas

If you thought that Legos were the coolest toys on the planet while you were growing up, it turns out that you were right.

Scientists at Lancaster University in England conducted an experimentin which they froze several Lego blocks to the lowest possible temperature, and what they discovered could be useful in the development of quantum computing.

Led by Dr. Dmitry Zmeev, the scientists used a custom-made dilution refrigerator,which the university saysis the most effective refrigerator in the world. The dilution refrigerator at Lancaster University can reach 1.6 millidegrees above absolute zero, or minus 459.67 degrees Fahrenheit (minus 273.15 Celsius). That is 200,000 times colder than room temperature and 2,000 times colder than deep space,according to the university.

The team of scientists placed a Lego figure along with four Lego blocks inside the dilution refrigerator to see if Legos could be a good thermal insulator.

We were trying to find a material that would be a thermal insulator at extremely low temperatures, yet would be relatively strong, Zmeev told CNN.

The Lego blocks looked like good candidates: the contact area between two blocks clamped together is very small, which prompts poor thermal conduction, yet the resulting structure is very robust. And indeed, our measurements confirmed this.

Legos aremade from ABS plastic, or acrylonitrile butadiene styrene. The plastic is known for its strength and durability. Among its other common uses are keys for computer keyboards.

Thermal insulation is critical to cryogenic engineering and low-temperature physics, but the materials for these applications are extremely expensive and are difficult to mold.

The very instrument the experiment was conducted with could benefit from its results. By allowing for a potentially more cost-effective solution to producing dilution refrigerators, using ABS as a thermal insulator in those refrigerators could aid in the development of quantum computing.

Very low temperatures provided by the dilution refrigerator are necessary for the operation of existing quantum computers, such as Googles, to cool down their qubits, Zmeev said.

A qubit is the basic unit of quantum information in quantum computing.

While its unlikely that Lego blocks per se will be used as a part of a quantum computer, weve found the right direction for creating cheap thermal insulators: 3D printing, Zmeev said. Lego is made from ABS plastic and one can also create ABS structures simply by 3D printing them. We are currently studying the properties of such 3D printed structures at ultralow temperatures close to absolute zero.

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Same Plastic That Make Legos Could Also Be The Best Thermal Insulators Used in Quantum Computers - KTLA Los Angeles

These days its easy to bemoan the state of innovation and the dynamism coming from Americas cradle of technological development in Silicon Valley.

The same companies that were praised for reimagining how people organized and accessed knowledge, interacted publicly, shopped for goods and services, conducted business, and even the devices on which all of these things are done, now find themselves criticized for the ways in which theyve abused the tools theyve created to become some of the most profitable and wealthiest ventures in human history.

Before the decade was even half over, the concern over the poverty of purpose inherent in Silicon Valleys inventions were given voice by Peter Thiel a man who has made billions financing the creation of the technologies whose paucity he then bemoaned.

We are no longer living in a technologically accelerating world, Thiel told an audience at Yale University in 2013. There is an incredible sense of deceleration.

In the six years since Thiel spoke to that audience, the only acceleration has been the pace of technologys contribution to the worlds decline.

However, there are some investors who think that the next wave of big technological breakthroughs are just around the corner and that 2020 will be the year that they enter the public consciousness in a real way.

These are the venture capitalists who invest in companies that develop so-called frontier technologies (or deep tech) things like computational biology, artificial intelligence or machine learning, robotics, the space industry, advanced manufacturing using 3D printing, and quantum computing.

Continued advancements in computational power, data management, imaging and sensing technologies, and materials science are bridging researchers ability to observe and understand phenomena with the potential to manipulate them in commercially viable ways.

As a result increasing numbers of technology investors are seeing less risk and more rewards in the formerly arcane areas of investing in innovations.

Established funds will spin up deep tech teams and more funds will be founded to address this market, especially where deep tech meets sustainability, according to Fifty Years investor, Seth Bannon. This shift will be driven from the bottom up (its where the best founder talent is heading) and also from the top down (as more and more institutional LPs want to allocate capital to this space).

In some ways, these investments are going to be driven by political necessity as much as technological advancement, according to Matt Ocko, a managing partner at the venture firm DCVC.

Earlier this year, DCVC closed on $725 million for two investment funds focused on deep technology investing. For Ocko, the geopolitical reality of continuing tensions with China will drive adoption of new technologies that will remake the American industrial economy.

Whether we like it or not, US-government-driven scrutiny of China-based technology will continue in 2020. Less of it will be allowed to be deployed in the US, especially in areas of security, networking, autonomous transportation and space intelligence, writes Ocko, in an email. At the same time, US DoD efforts to streamline procurement processes will result in increasingly tighter partnerships between the DoD and tech sector. The need to bring complex manufacturing, comms, and semiconductor technology home to the US will support a renaissance in distributed manufacturing/advanced manufacturing tech and a strong wave of semiconductor and robotic innovation.

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2020 will be the beginning of the tech industry's radical revisioning of the physical world - TechCrunch